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Article

Preanalytical, Analytical and Postanalytical Analyses on Corynebacterium spp. and Actinomycetaceae in Urine Samples of Patients with Suspected Urinary Tract Infection—A Hypothesis-Forming Observational Study

1
Institute for Medical Microbiology, Virology and Hygiene, University Medicine Rostock, 18057 Rostock, Germany
2
Department of Microbiology and Hygiene, Bundeswehr Hospital Hamburg, 20239 Hamburg, Germany
*
Authors to whom correspondence should be addressed.
Diagnostics 2024, 14(7), 746; https://doi.org/10.3390/diagnostics14070746
Submission received: 19 February 2024 / Revised: 24 March 2024 / Accepted: 28 March 2024 / Published: 30 March 2024
(This article belongs to the Special Issue One Health Approach to Diagnose and Treat Fungal/Bacterial Infections)

Abstract

:
A hypothesis-forming exploratory cross-sectional assessment was conducted to assess the occurrence and relevance of Gram-positive rod-shaped bacteria like Corynebacterium spp. and Actinomycetaceae in human urine samples. In total, 1170 urine samples from 1031 inpatients with suspected urinary tract infection were assessed for culture-based growth of Gram-positive rod-shaped bacteria applying API Coryne assays, matrix-assisted laser desorption–ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and in-house 16S rRNA gene sequencing. Overall, 502 different bacterial colonies from 346 urine samples taken from 324 inpatients were observed. The three quantitatively most abundant genera or genus clusters were Corynebacterium (254 isolates, 62%), Actinomyces/Winkia (79 isolates, 19%), and Actinotignum/Actinobaculum (29 isolates, 7%). Compared to sequencing, the diagnostic accuracy of all assessed competitor assays from the diagnostic routine was <80% for differentiation on the genus level and <30% for differentiation on the species level. Prolongated incubation for 4 days compared to 2 days resulted in additional detection of 15% of the totally recorded Gram-positive rod-shaped bacteria. An approximately 5-fold increased detection rate in mid-stream urine compared to urine acquired applying alternative sampling strategies was observed. In conclusion, in the rare event of the suspected clinical relevance of such findings, confirmatory testing with invasively sampled urine should be considered due to the high contamination rate observed in mid-stream urine. Confirmatory testing by DNA-sequencing methods should be considered if an exact identification of genus or species is regarded as relevant for the individual choice of the therapeutic strategy.

1. Introduction

The distal structures of the human urogenital tract are extensively physiologically colonized by bacteria and to a lesser extend also its proximal elements [1,2]. Accordingly, urine samples are prone to containing these bacteria. In the case of suspected urinary tract infection, this affects the decision on etiological relevance for the detected microorganisms. In addition, typical causative agents of urinary tract infections are characterized by “facultative pathogenicity”. This term describes a microorganism’s ability to act either as a harmless colonizer or as an agent able to initiate etiologically relevant infections depending on environmental and host-defense factors. Thereby, the concept of facultative pathogenicity is in pronounced conflict to the third historic Henle–Koch postulate. The latter said that pure cultures of an infectious agent should be sufficient conditions for the experimental induction of an associated infectious disease [3]. The fulfillment of this postulate would nowadays be called “obligate pathogenicity”. Such “obligate pathogenicity” is virtually never the case for microorganisms causing urinary tract infections, except for some rare exemptions like the mycobacteria in the tuberculosis complex.
However, urinary tuberculosis is infrequent in western industrialized countries. Instead, Escherichia coli, followed by enterococci, staphylococci, and Enterobacterales, different from E. coli like Klebsiella spp. and Proteus spp., are most frequently associated with non-nosocomial urinary tract infections [4,5]. In the case of nosocomial infections, the spectrum is slightly different with a broad spectrum of Enterobacterales next to enterococci and staphylococci as well as—to a lesser extend—Pseudomonas aeruginosa and Candida albicans being considered as potentially relevant [4,5].
However, all these species can be isolated as contaminants as well. To circumvent this problem, complex diagnostic interpretation guidelines like the German MiQ (“Mikrobiologisch-infektiologische Qualitätsstandards”/“Micrological/infectiological quality standards”) documents [5] include various factors like absolute quantification, consideration of pre-analytic features like the sampling strategy, as well as storage and transport conditions, etc., to provide recommendations for the assignment of likely etiological relevance for a diagnostic result.
Previously published works [6,7,8,9,10] strongly discourage microbiological urine assessments in the absence of inflammatory signs like leukocyturia, positive leukocyte esterase reaction or positive nitrite reaction in urine to reduce superfluous antimicrobial therapies in response to the misinterpretation of contaminants. However, the available interpretation criteria are based on probabilistic evidence. The variety of factors influencing the results of microbiological urine diagnostics can nevertheless lead to indistinguishable results both resulting from infection or colonization on an individual scale.
To provide an example of such multiple realizability, a high pathogen load of a pure culture of E. coli in urine, which can typically be found in the case of a “standard” urinary tract infection, could also be caused by a single species contamination combined with unfavorable storage and transport conditions. As shown decades ago, such unfavorable storage and transport conditions can alter pathogen loads in biological samples in different directions. This includes an increased die-off of particularly vulnerable microbial species, as well as overgrowth by less vulnerable ones [11].
Assignment of etiological relevance becomes even more challenging in the case of the detection of bacteria in diagnostic urine samples which have been described to infrequently cause urinary tract infections but which are very frequently part of the human resident flora [12]. Gram-positive rod-shaped bacteria are typical examples. Focusing on Corynebacterium spp., species like C. amylocatum, C. aurimucosum, C. glucoronolyticum, C. urealyticum, and C. pseudogenitalium, the latter also contributing to the formation of urinary stones due to high urease activity and associated alkalization of the urine, have been associated with urinary tract infections in previous works [13,14,15,16,17,18,19,20]. Actinomycetaceae have been reported as potentially relevant as well [21,22,23,24,25,26,27,28]. For Actinomyces spp., opportunistic infections of the urogenital tract have been associated with injuries to the skin or mucous membrane barrier due to trauma or surgery [21]. For Winkia neuii (formerly Actinomyces neuii), biofilm-associated urinary tract infections in the case of indwelling foreign materials have been reported [22,23]. For some Actinotignum spp. and Actinobaculum spp. like Actinotignum schaalii (formerly Actinobaculum schaalii), severe urinary tract infections with restricted treatment options due to highly resistant strains have been described [24,25,26,27,28]. Keeping the hypothetical etiological relevance even of such rarely diagnosed causes of urinary tract infections in mind, some authors have advocated not to regard mixed flora from urine as contamination, but to identify all encountered species [29,30]. However, such minority opinions need to be carefully balanced against associated risks of overtreatment and antimicrobial resistance selection as stated above [6,7,8,9,10]. This consideration stresses the importance for a rational assessment of the likely etiological relevance or irrelevance of diagnostic results.
To facilitate estimations of their potential etiological relevance, it is useful to have broader information on the expected frequency of isolations of Gram-positive rod-shaped bacteria from diagnostic urine samples. However, respective studies are scarce and diagnostic surveillance data might be compromised due to the fact that Gram-positive rod-shaped bacteria are frequently neglected during the diagnostic workup of urine samples, particularly when occurring as part of mixed bacterial flora [5]. Accordingly, a cross-sectional study was conducted to assess the abundance of Gram-positive rod-shaped bacteria in urine samples of inpatients with suspected urinary tract infections at a German tertiary hospital, with particular focus on Corynebacterium spp. and Actinomycetaceae. Some genera like Bifidobacterium spp., Gardnerella spp. and Lactobacillus spp. were deliberately excluded as components of the physiological urethral flora [31,32].
Also, the reliability of commonly applied diagnostic approaches, the effect of incubation time as well as preanalytical influences like the mode of urine sampling or factors with relevance for postanalytical interpretations like patient age and sex were assessed.

2. Materials and Methods

2.1. Study Design, Study Population and Assessed Preanalytical and Postanalytical Parameters

The study was designed as a hypothesis-forming explorative cross-sectional assessment. The analyses were conducted with urine samples collected within an eight-month study period at a Germany tertiary hospital from inpatients with suspected urinary tract infections. The recorded preanalytical parameters comprised the urine sampling strategy, including mid-stream or first jet urine, urine from an indwelling or an intermittent catheter, urine collected in a pot or a pouch, urine from an entero-vesical fistula or an ileal conduit, or urine invasively sampled via puncture of the bladder or the renal pelvis, as well as situations with insufficient information on the applied sampling approach. The collected patient data used for postanalytical assessments comprised age stratified by decades and sex.

2.2. Assessed Analytical Parameters, Inclusion and Exclusion Criteria

All assessed diagnostic urine samples were initially analyzed in a microbiological diagnostic routine laboratory accredited according to DIN EN ISO 15189 [33], which included cultural growth of aerobic bacteria for 40–48 h at 36 (±1) °C on Colombia agar enriched with 5% sheep blood (bioMerieux, Nürtingen, Germany). Instead of being disposed after the routine diagnostic procedures, the agar plates were qualitatively screened visually by experienced investigators for colony morphology of potential Gram-positive rod-shaped bacteria as part of this study. Colony morphologies untypical for Gram-positive rod-shaped bacteria as judged by the investigators were not analyzed further. Afterwards, the agar plates were incubated for additional 40–48 h at 36 (±1) °C, resulting in a second assessment after a total of 80–96 h. Exclusion criteria included the overgrowth of the agar medium by molds, negatively interfering with the detectability of colonies of Gram-positive rod-shaped bacteria. In case of overgrowth by Gram-negative bacteria, e.g., Enterobacterales like Proteus spp. showing swarming behavior, isolation on CNA agar (bioMerieux, Nürtingen, Germany) was used to suppress Gram-negative bacterial growth.
Suspected colonies were assessed with the diagnostic approaches as described in the “Analytical workflow” subheading below. Gram staining was conducted using a PREVI Color V2 automatic device (bioMerieux, Nürtingen, Germany) as recommended by a manufacturer.
Matrix-assisted laser desorption–ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis was performed using an Axima Assurance device (Shimadzu, Kyoto, Japan). The obtained spectra were analyzed using the database Saramis version 15.10.13–18.11.14 (bioMerieux, Nürtingen, Germany) and the database Myla version 15.09.–24.11.2014 (bioMerieux, Nürtingen, Germany). Biochemical assessment was conducted using the API Coryne assay (bioMerieux, Nürtingen, Germany) according to the manufacturer’s instructions.
As a reference method for this study, an in-house 16S rRNA gene sequencing protocol was applied. In detail, DNA extraction from pure colony material was conducted applying the QIAamp DNA Mini Kit (Qiagen, Hilden, Germany). Afterwards, 16S rRNA gene-based pan-bacterial PCR as described in [34] was run using the forward primer 16S8_27 (5′-AGAGTTTGATCMTGGCTCAG-3′) and the reverse primer 16S519 (5′-GWATTACCGCGGCKGCTG-3′). The run conditions comprised initial denaturation at 95 °C for 3 min followed by 30 cycles at 94 °C, 50 °C and 72 °C for one minute each with a subsequent final extension step at 72 °C for 5 min. Purification of obtained amplicons was based on agarose gel electrophoresis using 1.2% agarose gels. Subsequently, the amplicons were sent for commercial Sanger sequencing to the company Seqlab (Microsynth AG, Göttingen, Germany). Quality-control of the returned sequence files comprised assessment with the software Finch Trace Viewer version 1.4.0 (Geospiza Inc., Seattle, WA, USA). Afterwards, analysis using the Basic Local Alignment Search Tool (BLAST) provided by the National Center for Biotechnology Information (NCBI) [35] was conducted. For the interpretation of the database results, matches ≥ 99% for sequence identity were accepted as identifications at the species level, whereas matches between ≥97% and <99% for sequence identity were accepted as identifications at the genus level. In cases where repetition was required for the diagnostic steps, isolates were deep-frozen at −80 °C in cryotubes (Pro-Lab Diagnostics, Richmond Hill, ON, Canada).

2.3. Analytical Workflow

The analytical workflow in case of observation of bacterial colonies suspected of resulting from Gram-positive rod-shaped bacterial growth is summarized in Table 1. In short, Gram-staining was used to exclude Gram-morphologies other than Gram-positive rod-shaped or coccoid bacteria. Afterwards, MALDI-TOF-MS was used to further exclude non-target organisms including species like Bifidobacterium, Gardnerella vaginalis or Lactobacillus, which were considered out of focus for the present assessment. Biochemical results using the API Coryne approach and 16S rRNA gene sequencing, of which the latter was used as reference testing, were added, before Gram-positive rod-shaped bacterial isolates were finally subjected to deep-freeze storage at −80 °C as Microbank-cryostocks (Pro-Lab Diagnostics, Round Rock, TX, USA).

2.4. Taxonomical Nomenclature Use

The databases applied for the identification of the bacteria partly provided genus and species names which now have to be considered as outdated. In order not to alter the obtained study results, the outdated nomenclature as provided by the databases is used in the tables in Appendix A of this work. Whenever necessary for understanding the study results, reference to the up-to-date taxonomy is provided in the main manuscript text and its tables. For the presented study, nomenclature changes within the family Actinomycetaceae and, thereby, within the genera Actinomyces and Winkia, as well as within the genera Actinotignum and Actinobaculum [36], are of particular relevance. Therefore, Actinomyces and Winkia as well as Actinotignum and Actinobaculum are used as genus clusters in the following sections.

2.5. Ethics

Ethical clearance for the study was obtained from the ethics committee of the Medical Faculty of the University of Rostock (reference number A2019-0021), which allowed the anonymized data assessment without informed consent. The study was conducted in line with both National German laws and the Declaration of Helsinki and all its amendments.

3. Results

3.1. Characterization of the Study Population

Within an 8-month study interval, a total of 1170 urine samples from 1031 inpatients with suspected urinary tract infection at a tertiary hospital were included in the assessment, among them follow-up samples from a total of 139 patients. Details on the composition of the study population are indicated in Table 2. In short, there was a quantitatively moderate dominance of male patients. The mean patient age was 54 years in a right-shifted distribution, with the youngest patient being in the first and the oldest in the 96th year of age at the time of the assessment.

3.2. Analytical Assessments on Gram-Positive Rod-Shaped Bacteria in Diagnostic Urine Samples

A total of 502 different bacterial colonies from 346 urine samples taken from 324 inpatients were suspected of containing Gram-positive rod-shaped bacterial growth and thus subjected to further downstream analysis. Applying the diagnostic workflow and the exclusion criteria as indicated in the Methods section, the number of isolates subjected to diagnostic MALDI-TOF mass spectrometry, biochemical assessment based on the API Coryne assay, and 16S rRNA gene sequencing were n = 441, n = 452, and n = 429, respectively. The higher number of API Coryne assessments in spite of this assay’s subordinate position in the downstream analysis of the diagnostic workflow is a consequence of the inclusion of results from the routine diagnostic setting, resulting in API Coryne assessments of 320 urine samples taken from 302 patients.
Focusing on the excluded isolates, 61 out of 502 initially selected suspected colonies were a priori excluded on the MALDI-TOF MS detection level due to non-matching Gram staining results or as non-target organisms like Bifidobacterium species, Gardnerella vaginalis, or Lactobacillus species. Based on the Myla database results of the MALDI-TOF assessments, a further 50 isolates were excluded as non-target organisms. From 429 isolates finally subjected to diagnostic 16S rRNA gene sequencing, another 17 isolates were excluded as non-target microorganisms, resulting in a total of 412 sequence-confirmed Gram-positive rod-shaped bacteria, isolated from 298 urine samples taken from 282 inpatients used for post-analytical downstream analysis.
Among the sequence-confirmed Gram-positive rod-shaped bacteria, the three quantitatively most abundant genera were Corynebacterium (254 isolates, 62%), Actinomyces/Winkia (79 isolates, 19%), and Actinotignum/Actinobaculum (29 isolates, 7%). The numbers of assessed isolates without conclusive results applying MALDI-TOF-MS using the Saramis database, MALDI-TOF-MS using the Myla database, API Coryne-based biochemistry, and 16S rRNA gene sequencing were n = 326 (74%), n = 89 (20%), n = 1 (0%), and n = 21 (5%), respectively. Of note, 16S rRNA gene sequencing-based differentiation succeeded for 284 isolates missed by the Saramis database and for 75 isolates missed by the Myla database.
Details on the diagnostic results obtained with the different diagnostic approaches are provided in Appendix A, Table A1. In summary, considerable mismatching of the results of the routine diagnostic standard procedures MALDI-TOF-MS and API-Coryne-based biochemical assessment compared to 16S rRNA gene sequencing, which was used as a reference method for this study, were seen for the assessed Gram-positive rod-shaped bacteria. In addition, the matching of MALDI-TOF-MS results with 16S rRNA sequencing relevantly depended on the used MALDI-TOF-MS database. MALDI-TOF-MS- and biochemistry-based identifications were confirmed by 16S rRNA sequencing in 14.3–29.1% of the cases at the species level and in 51.5–65.2% of the cases on genus level. While the applied Saramis database allowed for better matching of MALDI-TOF-MS results with 16S rRNA sequencing on genus level compared to the Myla database, the opposite was the case for discriminations at the species level (Table 3). Additionally, the Myla database had a lower rate of a priori non-interpretable results as mentioned above.
Focusing on the genera Corynebacterium, Actinomyces/Winkia, and Actinotignum/Actinobaculum, 16S rRNA sequence-based confirmation of MALDI-TOF-MS-based and API Coryne-based differentiation was accomplished at the species level in 5.9–15.7%, 3.8–29.1%, and 0–6.9% of the cases, respectively, and at the genus level in 33.1–71.3%, 12.7–75.9%, and 0–20.7% of the cases, respectively. More reliable MALDI-TOF-MS differentiation results were obtained with the Myla database for the genera Corynebacterium and Actinomyces, while the Saramis database was more reliable for the identification of Actinotignum/Actinobaculum. Details are provided in Table 3.
When focusing on the duration of incubation, prolongated incubation from 48 h to 96 h did not increase the detection rate of Gram-positive rod-shaped bacteria for 85% of the samples. For 15%, however, additional growth of such microorganisms could be confirmed after 96 h of incubation. These 15% comprised 11% of cases in which additional Gram-positive rod-shaped bacteria grew after 96 h, although other colony morphologies of different Gram-positive rod-shaped bacterial species had been observed already after 48 h, while in 4% of the cases growth of Gram-positive rod-shaped bacteria was first detected after 4 days of incubation. Details on the distribution are shown in Appendix A, Table A2; an overview on the bacteria isolated after 96 h incubation is provided in Appendix A, Table A3 and Table A4.

3.3. Preanalytical Assessments on Gram-Positive Rod-Shaped Bacteria in Diagnostic Urine Samples

Preanalytical assessments were focused on associations of the urine sampling strategy and the culture-based detection of Gram-positive rod-shaped bacteria. As detailed in Table 4 and Appendix A, Table A5, the vast majority of Gram-positive rod-shaped bacteria were isolated from non-invasively taken urine samples like mid-stream urine, first jet urine, urine collected in a pot, or urine samples acquired by catheterization. In contrast, detecting Gram-positive rod-shaped bacteria were rare events from invasively acquired urine samples, e.g., urine sampled via puncture of the bladder or the renal pelvis. Of note, nearly half of the mid-stream urine samples showed growth of Gram-positive rod-shaped bacteria, while this was the case for only about 10% of all urine samples. Again, Corynebacterium spp. and Actinomycetaceae quantitatively dominated.

3.4. Postanalytical Assessments on Gram-Positive Rod-Shaped Bacteria in Diagnostic Urine Samples

Postanalytical assessments were focused on associations of detections of Gram-positive rod-shaped bacteria with sex and age of the study population. As detailed in Table 5 and Appendix A, Table A6, Corynebacterium spp. were slightly more frequent in urine samples of females, while Actinomyces/Winkia spp. were more often isolated from male patients. For the Gram-positive rod-shaped bacteria in total, the female:male ratio was 45:55. In more detail, C. aurimucosum and Corynebacterium “Smarlab Biomol” were more frequently found in samples from female patients, whereas A. turicensis, A. radingae, C. glucoronolyticum, C. jeikeium, C. pseudogenitalium, and C. tuberculostaericum were more frequently found in samples from male patients.
Regarding the associations of Gram-positive rod-shaped bacteria with the age of the study population (stratified by decades), details are provided in Table 6 and Table 7 as well as in Appendix A, Table A7. In short, Gram-positive rod-shaped bacteria were most common in the age ranges of 31–40, 41–50, and 51–60 years (one detection per 2.3 urine cultures) and least frequent in the ranges of 81–90 years (one detection per 4.1 urine cultures). Also, there was a tendency for fewer detections in the first age decade. For Corynebacterium spp. and Actinomyces/Winkia spp., no age association was observed. For Actinotignum/Actinobaculum spp., in contrast, detections occurred more frequently in patients older than 30 years.

4. Discussion

The study was performed as a broad assessment on Gram-positive rod-shaped bacteria in human urine samples, providing a representative data basis by assessing a relevant number of samples with routine diagnostic methods in an accredited laboratory. This approach led to a number of results.
Focusing on the analytical assessments, it could be shown that commonly applied routine diagnostic approaches like MALDI-TOF-MS or semi-automated biochemical assays showed imperfect diagnostic reliability for discrimination at the genus level and even less reliable results at the species level when applied with Gram-positive rod-shaped bacteria isolated from urine samples compared to 16S rRNA gene sequencing. For MALDI-TOF-MS results, the diagnostic accuracy largely depended on the quality of the applied database as confirmed by the comparison of the Saramis and the Myla approach. In our hands, the API Coryne assay still showed good matching with 16S rRNA gene sequencing for individual, potentially relevant species like C. glucoronlyticum, C. urealyticum, A. turicensis, and A. radingae (details in Appendix A, Table A1). For other identification results, the matching was considerably worse.
The observed limitations of microbiological diagnostic standard approaches when applied with rarely differentiated Gram-positive rod-shaped microorganisms are well-known from previous studies [37,38,39,40,41,42], and resulting minor and major detection errors are not surprising in this respect. Consequently, surveillance assessments on Gram-positive rod-shaped bacteria based solely upon routine diagnostic results should be interpreted with care and medical microbiologists need to be aware of diagnostic failure in the routine situation when relying on these methods.
However, there are also evidence-supported reasons not to overestimate the reliability of diagnostic 16S rRNA sequence assessment based on publicly accessible databases, as carried out in this study, which are not quality-controlled for in vitro diagnostic use. It has been repeatedly shown that sequences within such public databases have been erroneously assigned [43,44,45,46,47,48], resulting in the risk of non-conclusive or even false diagnostic results as well. Although 16S rRNA gene sequencing has been applied as diagnostic reference approach in the here presented study, the correctness of its results cannot be definitely considered as guaranteed, a residual uncertainty of this work which is methodically immanent. To resolve this problem, quality-controlled diagnostic sequencing solutions labeled for in vitro diagnostic use also covering rarely isolated pathogens would be highly desirable for microbiological routine diagnostic laboratories. This is so far an unmet diagnostic need.
Focusing on the incubation time, it could be shown that the majority of Gram-positive rod-shaped bacteria could be detected after 48 h of incubation, while only a minor effect could be achieved by prolongated incubation for 96 h. Thus, the work is in partial contradiction to previous assessments favoring prolongated incubation of Gram-positive rod-shaped bacteria for about five days [49,50]. It can only be speculated whether growth-supporting matrix effects of the urine samples could have played a role in the here-presented study. Hypothetically, Gram-positive rod-shaped bacteria might remain more vital in the moist environment of urine during sampling and storage compared to other sample materials.
Regarding the preanalytical stratification by the mode of urine sample acquisition, the strong proportional dominance of the detection of Gram-positive rod-shaped bacteria in mid-stream urine samples compared to their low abundance in invasively acquired urine samples makes contamination events in mid-stream urine highly likely. As Gram-positive rod-shaped bacteria are standard colonizers of the human skin, contamination events in the colonized distal urogenital tract may easily occur. The few detections on catheters were restricted to indwelling urinary catheters. For this type of catheter, occlusion due to crystal formation in the course of infections with Corynebacterium spp. has been reported [14]. Further, severe Actinotignum schaalii catheter-associated infections have been described [51]. The etiological role of a single catheter-associated A. schaalii-detection in our study remained, however, unresolved.
In international literature, increased proportions of Corynebacterium spp.-infections including urinary tract infections and usually associated with severe, immunocompromising underlying medical conditions were observed in males compared to females [52,53,54]. However, colonization of the urinary tract with Corynebacterium spp. was also shown to be common in healthy young males [55]. In the study presented here, only minor differences between male and female patients regarding the detection of Gram-positive rod-shaped bacteria were observed. Focusing on such bacteria with reported potential relevance for urinary tract infections [13,14,15,16,17,18,19,20], C. aurimucosum was more frequently observed in females, and C. glucoronolyticum and C. pseudogenitalium in males. However, such minor differences have to be interpreted with care considering the low total numbers of detections and the uncertain etiological relevance of the respective isolates.
Regarding patient age, increased detection rates of Gram-positive rod-shaped bacteria in patients older than 60 years of age as reported by others [56,57,58] could be shown for Actinotignum/Actinobaculum spp., while Corynebacterium spp. and Actinomyces/Winkia spp. were evenly distributed over the various age ranges, grouped according to decade. Also, in contrast to reports by others [59,60], Actinotignum/Actinobaculum spp. isolates were widely missing in young minors. Again, low total numbers might be one reason for the observed discrepancy.
The study has a number of limitations. First, apart from sex and age, no further information on the study population was collected, which is a deviation from the STARD criteria for diagnostic accuracy studies [61] focusing on the assay comparison component of the assessment. In addition, this limitation did not allow any association of detected Gram-positive rod-shaped bacteria with clinical symptoms or clinical courses of the patients. In this respect, the study does not allow any direct conclusions on the likely etiological relevance of the isolated bacteria. Joint study approaches between clinical and laboratory departments might resolve this limitation in future assessments. Of note, however, bacterial species for which potential etiological relevance had previously been suggested [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28] were indeed recorded. Second, this interpretative challenge was even aggravated by the fact that the study design neither included quantification of the isolates nor assessments on their occurrence in pure or mixed cultures as well as on the composition of such mixed cultures. Respective sub-stratification would have made interpretations of this hypothesis-forming holistic study approach even more challenging but should be included in confirmatory assessments. Third, detailed information on the storage and transport conditions of the individual samples was not collected, making estimations of the influence of these factors [11] on the likelihood of the detection of Gram-positive rod-shaped bacteria unfeasible. Future studies should consider such interfering factors as well. Fourth, in spite of the high total number of assessed samples, species rarely associated with urinary tract infections were also rarely found in this assessment, making the estimation of the potential relevance of minor quantitative differences challenging. Multicentric-study approaches might resolve this problem in future studies.

5. Conclusions

In spite of the abovementioned limitations, the study suggests a number of consequences. The results of the diagnostic standard procedures for the discrimination of Gram-positive rod-shaped bacteria from urinary samples have to be interpreted with care due to imperfect diagnostic accuracy, particularly at the species level. Each laboratory should consider the option of step-wise confirmatory testing, potentially including laborious and time-consuming procedures like sequencing if a species-level identification is considered to be relevant in individual cases. The relevance of age and sex for the isolation of Gram-positive rod-shaped bacteria from urine seems negligible. Detection rates of Gram-positive rod-shaped bacteria are much higher from mid-stream urine compared to invasively sampled urine, stressing the high likelihood of sample contamination in the distal urinary tract. As a consequence, confirmatory testing with invasively sampled urine should be considered if etiological relevance of identified Gram-positive rod-shaped bacteria in urine samples is considered, e.g., in case of repeated detections of such bacteria in subsequently collected urine samples and lacking clinical response to the medical treatment of other likely causative agents of persisting urinary tract infection. In individual cases, prolongated incubation for about 4 days can be considered in the case of suspicion of otherwise undetected urinary tract infections with Gram-positive rod-shaped bacteria, because a minority of the isolates were not recorded after the standard incubation time of 40–48 h.

Author Contributions

Conceptualization, A.P. and P.W.; methodology, K.S. and A.P.; software, K.S.; validation, K.S., P.W. and A.P.; formal analysis, K.S.; investigation, K.S.; resources, A.P.; data curation, K.S.; writing—original draft preparation, H.F.; writing—review and editing, H.F., K.S., P.W. and A.P.; visualization, K.S. and H.F.; supervision, A.P. and P.W.; project administration, A.P. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Ethical clearance for the study was obtained from the ethics committee of the Medical Faculty of the University of Rostock (reference number A2019-0021), which allowed the anonymized data assessment without informed consent. The study was conducted in line with both National German laws and the Declaration of Helsinki and all its amendments.

Informed Consent Statement

Anonymized data assessment without informed consent was accommodated by the ethical clearance in line with national German law.

Data Availability Statement

All relevant data are provided in the manuscript and Appendix A. Raw data can be made available upon reasonable request. Sequence data are not deposited in databases, because sequencing has been used for diagnostic purposes, and so the identity of the assessed microorganisms cannot be considered as definitely guaranteed.

Conflicts of Interest

The authors declare no conflicts of interest.

Appendix A

Table A1. Diagnostic results as obtained with the different applied identification approaches in alphabetic order. Results are presented exactly as provided by the applied databases, explaining the partly outdated nomenclature.
Table A1. Diagnostic results as obtained with the different applied identification approaches in alphabetic order. Results are presented exactly as provided by the applied databases, explaining the partly outdated nomenclature.
Diagnostic ResultMALDI-TOF-MS (Saramis Database,
n = 441), n (%)
MALDI-TOF-MS (Myla Database,
n = 441), n (%)
Biochemical Differentiation (API Coryne,
n = 452), n (%)
16S rRNA Gene Sequencing
(n = 412), n (%)
Actinobaculum massiliense---1 (0.2%)
Actinobaculum schaalii11 (2.5%)--18 (4.4%)
Actinobaculum sp. V04 257809/08---10 (2.4%)
Actinomyces europaeus-1 (0.2%) 4 (1.0%)
Actinomyces hominis---1 (0.2%)
Actinomyces neuii2 (0.5%)29 (7.4%)-4 (1.0%)
Actinomyces neuii ssp. anitratus--17 (3.8%)-
Actinomyces neuii ssp. neuii--12 (2.7%)-
Actinomyces radingae-10 (2.5%)12 (2.7%)6 (1.5%)
Actinomyces radingae/Aerococcus viridans-1 (0.2%)--
Actinomyces sp.7 (1.6%)---
Actinomyces sp. 13-114---1 (0.2%)
Actinomyces sp. 13-605---8 (1.9%)
Actinomyces sp. 2234/04---2 (0.5%)
Actinomyces sp. “ARUP UnID60”---26 (6.3%)
Actinomyces sp. S5-BM9---1 (0.2%)
Actinomyces sp. SD1---5 (1.2%)
Actinomyces turicensis2 (0.5%)38 (9.7%)41 (9.1%)17 (4.1%)
Actinomyces urogenitalis---4 (1.0%)
Alloscardovia omnicolens---9 (2.2%)
Arcanobacterium pyogenes--2 (0.4%)-
Arcanobacterium pyogenes/Brevibacterium spp.--1 (0.2%)-
Arthrobacter albus---1 (0.2%)
Arthrobacter cumminsii-2 (0.5%)-1 (0.2%)
Arthrobacter spp.--23 (5.1%)-
Bacillus badius-3 (0.8%) -
Bacillus sp. PD1B---1 (0.2%)
Bacillus thuringiensis-1 (0.2%)--
bacterium str. Rauti---3 (0.7%)
Brevibacterium spp.--30 (6.6%)-
Brevibacterium spp./Arcanobacterium bernardiae/Gardnerella vaginalis--1 (0.2%)-
Brevibacterium spp./Gardnerella vaginalis/Actinomyces neuii ssp. anitratus--1 (0.2%)-
Cellumonas spp./Microbacterium spp.--7 (1.5%)-
Clostridium cadaveris-1 (0.2%)--
Clostridium clostridioforme-1 (0.2%)--
Clostridium histolyticum-1 (0.2%)--
Corynebacteriaceae bacterium “ARUP UnID261”---1 (0.2%)
Corynebacteriaceae bacterium “ARUP UnID268”---1 (0.2%)
Corynebacterium afermentans---1 (0.2%)
Corynebacterium afermentans/coyleae--14 (3.1%)-
Corynebacterium amycolatum1 (0.2%)--7 (1.7%)
Corynebacterium amycolatum/jeikeium/xerosis1 (0.2%)---
Corynebacterium amycolatum/xerosis51 (11.6%)85 (21.7%)1 (0.2%)-
Corynebacterium argentoratense--19 (4.2%)-
Corynebacterium aurimucosum-7 (1.8%)-11 (2.7%)
Corynebacterium aurimucosum/Rhodococcus erythropolis-1 (0.2%)--
Corynebacterium auris/Turicella otitidis--15 (3.3%)-
Corynebacterium bovis--6 (1.3%)-
Corynebacterium confusum-1 (0.2%)-1 (0.2%)
Corynebacterium coyleae-11 (2.8%)-2 (0.5%)
Corynebacterium freneyi-2 (0.5%)--
Corynebacterium glucuronolyticum18 (4.1%)50 (12.8%)55 (12.2%)42 (10.2%)
Corynebacterium glucuronolyticum/Arcanobacterium pyogenes/Gardnerella vaginalis/Arcanobacterium haemolyticum--1 (0.2%)-
Corynebacterium group F1--5 (1.1%)-
Corynebacterium group G--6 (1.3%)-
Corynebacterium imitans---4 (1.0%)
Corynebacterium jeikeium1 (0.2%)5 (1.3%)22 (4.9%)3 (0.7%)
Corynebacterium macginleyi1 (0.2%)1 (0.2%)2 (0.4%)1 (0.2%)
Corynebacterium massiliense---1 (0.2%)
Corynebacterium minutissimum---3 (0.7%)
Corynebacterium mucifaciens-1 (0.2%)--
Corynebacterium propinquum--66 (14.6%)-
Corynebacterium pseudodiphtheriticum--4 (0.9%)-
Corynebacterium pseudogenitalium---29 (7.0%)
Corynebacterium pseudotuberculosis--5 (1.1%)-
Corynebacterium renale-1 (0.2%)--
Corynebacterium riegelii---1 (0.2%)
Corynebacterium simulans---1 (0.2%)
Corynebacterium singulare---1 (0.2%)
Corynebacterium sp.18 (4.1%)--9 (2.2%)
Corynebacterium sp. 2012257588---1 (0.2%)
Corynebacterium sp. 2012259355---1 (0.2%)
Corynebacterium sp. 31595---4 (1.0%)
Corynebacterium sp. 59614---1 (0.2%)
Corynebacterium sp. 707471/2012---12 (2.9%)
Corynebacterium sp. “ARUP UnID231”---1 (0.2%)
Corynebacterium sp. “ARUP UnID245”---3 (0.7%)
Corynebacterium sp. “ARUP UnID281”---5 (1.2%)
Corynebacterium sp. “ARUP UnID60”---1 (0.2%)
Corynebacterium sp. ATCC 6931---9 (2.2%)
Corynebacterium sp. canine oral taxon 424, OH 977---4 (1.0%)
Corynebacterium sp. M3T9B3---2 (0.5%)
Corynebacterium sp. MOLA 35---1 (0.2%)
Corynebacterium sp. NML96-0085---5 (1.2%)
Corynebacterium sp. NML90-0020---1 (0.2%)
Corynebacterium sp. S504---1 (0.2%)
Corynebacterium sp. “Smarlab Biomol”---67 (16.3%)
Corynebacterium sp. R-45865---5 (1.2%)
Corynebacterium sp. R603---2 (0.5%)
Corynebacterium striatum-1 (0.2%)--
Corynebacterium striatum/amycolatum--33 (7.3%)-
Corynebacterium tuberculostearicum-33 (8.4%)-5 (1.2%)
Corynebacterium urealyticum1 (0.2%)-9 (2.0%)2 (0.5%)
Corynebacterium ureicelerivorans---2 (0.5%)
Corynebacterium xerosis-1 (0.2%)-2 (0.5%)
Dermabacter hominis1 (0.2%)2 (0.5%)6 (1.3%)2 (0.5%)
Dermabacter sp. AD186---1 (0.2%)
Erysipelothrix rhusiopathiae--4 (0.9%)-
Gardnerella vaginalis--15 (3.3%)-
Gardnerella vaginalis/Erysipelothrix rhusiopathiae/Brevibacterium spp./Listeria monocytogenes/innocua/Propionibacterium avidum--1 (0.2%)-
Gardnerella vaginalis/Propionibacterium avidum--1 (0.2%)-
Listeria weishimeri-1 (0.2%)--
Lysinibacillus sphaericus-1 (0.2%)--
Microbacterium arborescens-1 (0.2%)--
Mycobacterium bovis/fortuitum/tuberculosis-1 (0.2%)--
Mycobakterium intracellulare-3 (0.8%)--
Mycobacterium kansasii-1 (0.2%)--
Mycobacterium smegmatis-1 (0.2%)--
No identification result326 (73.9%)89 (22.8%)1 (0.2%)21 (5.1%)
Paenibacillus durus-1 (0.2%)--
Propionibacterium acnes--2 (0.4%)-
Propionibacterium acnes/Arthrobacter spp./Actinomyces radingae--2 (0.4%)-
Propionibacterium avidum-2 (0.5%)2 (0.4%)-
Pseudoclavibacter bifida---1 (0.2%)
Pseudoclavibacter faecalis---1 (0.2%)
Rhodococcus sp.--7 (1.5%)-
Rothia dentocariosa--1 (0.2%)-
uncultured bacterium clone JSC7-39---1 (0.2%)
Zimmermannella sp. “ARUP UnID673”---1 (0.2%)
Table A2. Proportions (in %) of agar plates of 1170 assessed urine samples focusing on the detection of Gram-positive rod-shaped bacteria comparing day 2 and day 4 of growth.
Table A2. Proportions (in %) of agar plates of 1170 assessed urine samples focusing on the detection of Gram-positive rod-shaped bacteria comparing day 2 and day 4 of growth.
Growth of Gram-Positive Rod-Shaped Bacteria on Day 2No growth of Gram-Positive Rod-Shaped Bacteria on Day 2
Additional growth of Gram-positive rod-shaped bacteria on day 411%4%
No additional growth of Gram-positive rod-shaped bacteria on day 459%26%
Table A3. Microorganisms isolated from agar plates showing no growth of Gram-positive rod-shaped bacteria at day 2 but from which Gram-positive rod-shaped bacteria were isolated at day 4. Ordered by number of isolation events. Results are presented exactly as provided by the applied database, explaining the partly outdated nomenclature.
Table A3. Microorganisms isolated from agar plates showing no growth of Gram-positive rod-shaped bacteria at day 2 but from which Gram-positive rod-shaped bacteria were isolated at day 4. Ordered by number of isolation events. Results are presented exactly as provided by the applied database, explaining the partly outdated nomenclature.
SpeciesNumber (n)
Actinobaculum schaalii3
Actinomyces sp. “ARUP UnID60”3
Corynebacterium glucuronolyticum3
Corynebacterium sp. 707471/20123
Alloscardovia omnicolens2
Corynebacterium pseudogenitalium2
Not identified2
Actinobaculum sp. V04 257809/081
Actinomyces turicensis1
bacterium str. Rauti1
Corynebacterium imitans1
Corynebacterium sp.1
Corynebacterium sp. “Smarlab Biomol”1
Corynebacterium sp. R-458651
Corynebacterium tuberculostearicum1
Table A4. Microorganisms isolated from agar plates showing growth of Gram-positive rod-shaped bacteria at day 2 and from which additional Gram-positive rod-shaped bacteria were isolated at day 4. Ordered by number of isolation events. Results are presented exactly as provided by the applied database, explaining the partly outdated nomenclature.
Table A4. Microorganisms isolated from agar plates showing growth of Gram-positive rod-shaped bacteria at day 2 and from which additional Gram-positive rod-shaped bacteria were isolated at day 4. Ordered by number of isolation events. Results are presented exactly as provided by the applied database, explaining the partly outdated nomenclature.
SpeciesNumber (n)
Corynebacterium sp. “Smarlab Biomol”15
Corynebacterium glucuronolyticum13
Actinomyces turicensis6
Corynebacterium pseudogenitalium6
Actinomyces sp. “ARUP UnID60”5
Not identified4
Actinomyces sp. 13-6053
Corynebacterium amycolatum3
Corynebacterium sp. 707471/20123
Corynebacterium sp. R-458653
Actinobaculum schaalii2
Actinobaculum sp. V04 257809/082
Actinomyces sp. SD12
Corynebacterium sp.2
Corynebacterium sp. 315952
Actinomyces europaeus1
Actinomyces sp. 2234/041
Actinomyces urogenitalis1
Alloscardovia omnicolens1
Bacillus sp. PD1B1
Brevibacterium sp. TSW19BA71
Corynebacterium afermentans1
Corynebacterium aurimucosum1
Corynebacterium massiliense1
Corynebacterium singulare1
Corynebacterium sp. “ARUP UnID245”1
Corynebacterium sp. “ARUP UnID60”1
Corynebacterium sp. ATCC 69311
Corynebacterium sp. NML90-00201
Corynebacterium sp. NML96-00851
Corynebacterium sp. R6031
Corynebacterium urealyticum1
Pseudoclavibacter bifida1
Pseudoclavibacter faecalis1
Table A5. Distribution of the species as assessed with 16S rRNA gene sequencing over the different urine sampling approaches, ordered by number. Results are presented exactly as provided by the applied database, explaining the partly outdated nomenclature.
Table A5. Distribution of the species as assessed with 16S rRNA gene sequencing over the different urine sampling approaches, ordered by number. Results are presented exactly as provided by the applied database, explaining the partly outdated nomenclature.
SpeciesTotalMid-Stream UrineUnknown Urine Sampling ApproachUrine Sampled in a PouchUrine from an Indwelling CatheterUrine from an Ileal ConduitUrine from an Intermittent Urinary CatheterUrine from an Entero-Vesical FistulaUrine Collected in a Pot
Corynebacterium sp. “Smarlab Biomol”67596010010
Corynebacterium glucuronolyticum42393000000
Corynebacterium pseudogenitalium29251201000
Actinomyces sp. “ARUP UnID60”26222100100
Not identified22184000000
Actinobaculum schaalii18161010000
Actinomyces turicensis17121310000
Corynebacterium sp. 707471/201212110000100
Corynebacterium aurimucosum1183000000
Actinobaculum sp. V04 257809/081082000000
Alloscardovia omnicolens972000000
Corynebacterium sp.990000000
Corynebacterium sp. ATCC 6931990000000
Actinomyces sp. 13-605862000000
Corynebacterium amycolatum761000000
Actinomyces radingae651000000
Actinomyces sp. SD1550000000
Corynebacterium sp. “ARUP UnID281”550000000
Corynebacterium sp. NML96-0085550000000
Corynebacterium sp. R-45865541000000
Corynebacterium tuberculostearicum541000000
Actinomyces europaeus440000000
Actinomyces neuii440000000
Actinomyces urogenitalis421100000
Corynebacterium imitans431000000
Corynebacterium sp. 31595430000001
Corynebacterium sp. canine oral taxon 424, OH 977440000000
bacterium str. Rauti330000000
Corynebacterium jeikeium330000000
Corynebacterium minutissimum330000000
Corynebacterium sp. “ARUP UnID245”321000000
Actinomyces sp. 2234/04220000000
Brevibacterium paucivorans201010000
Brevibacterium sp. TSW19BA7220000000
Corynebacterium coyleae220000000
Corynebacterium sp. M3T9B3220000000
Corynebacterium sp. R603220000000
Corynebacterium urealyticum211000000
Corynebacterium ureicelerivorans220000000
Corynebacterium xerosis211000000
Dermabacter hominis220000000
Actinobaculum massiliense110000000
Actinomyces hominis110000000
Actinomyces sp. 13-114110000000
Actinomyces sp. S5-BM9110000000
Arthrobacter albus110000000
Arthrobacter cumminsii110000000
Bacillus sp. PD1B110000000
Corynebacteriaceae bacterium “ARUP UnID261”110000000
Corynebacteriaceae bacterium “ARUP UnID268”110000000
Corynebacterium afermentans110000000
Corynebacterium confusum110000000
Corynebacterium macginleyi110000000
Corynebacterium massiliense110000000
Corynebacterium riegelii110000000
Corynebacterium simulans110000000
Corynebacterium singulare110000000
Corynebacterium sp. “ARUP UnID231”110000000
Corynebacterium sp. “ARUP UnID60”110000000
Corynebacterium sp. 2012257588110000000
Corynebacterium sp. 2012259355101000000
Corynebacterium sp. 59614110000000
Corynebacterium sp. MOLA 35110000000
Corynebacterium sp. NML90-0020110000000
Corynebacterium sp. S504110000000
Dermabacter sp. AD186110000000
Pseudoclavibacter bifida110000000
Pseudoclavibacter faecalis110000000
uncultured bacterium clone JSC7-39110000000
Zimmermannella sp. “ARUP UnID673”110000000
Table A6. Distribution of the of the species as assessed with 16S rRNA gene sequencing over the female and male sex, ordered by number. Results are presented exactly as provided by the applied database, explaining the partly outdated nomenclature.
Table A6. Distribution of the of the species as assessed with 16S rRNA gene sequencing over the female and male sex, ordered by number. Results are presented exactly as provided by the applied database, explaining the partly outdated nomenclature.
SpeciesTotalMaleFemale
Corynebacterium sp. “Smarlab Biomol”671156
Corynebacterium glucuronolyticum42384
Corynebacterium pseudogenitalium29245
Actinomyces sp. “ARUP UnID60”261511
Not identified221111
Actinobaculum schaalii18126
Actinomyces turicensis17134
Corynebacterium sp. 707471/201212120
Corynebacterium aurimucosum1138
Actinobaculum sp. V04 257809/081055
Alloscardovia omnicolens945
Corynebacterium sp.990
Corynebacterium sp. ATCC 6931918
Actinomyces sp. 13-605853
Corynebacterium amycolatum716
Actinomyces radingae660
Actinomyces sp. SD1550
Corynebacterium sp. “ARUP UnID281”514
Corynebacterium sp. NML96-0085523
Corynebacterium sp. R-45865550
Corynebacterium tuberculostearicum541
Actinomyces europaeus422
Actinomyces neuii422
Actinomyces urogenitalis422
Corynebacterium imitans422
Corynebacterium sp. 31595431
Corynebacterium sp. canine oral taxon 424, OH 977431
bacterium str. Rauti321
Corynebacterium jeikeium330
Corynebacterium minutissimum321
Corynebacterium sp. “ARUP UnID245”303
Actinomyces sp. 2234/04202
Brevibacterium paucivorans220
Brevibacterium sp. TSW19BA7202
Corynebacterium coyleae211
Corynebacterium sp. M3T9B3202
Corynebacterium sp. R603211
Corynebacterium urealyticum202
Corynebacterium ureicelerivorans211
Corynebacterium xerosis220
Dermabacter hominis220
Actinobaculum massiliense101
Actinomyces hominis101
Actinomyces sp. 13-114101
Actinomyces sp. S5-BM9101
Arthrobacter albus101
Arthrobacter cumminsii101
Bacillus sp. PD1B110
Corynebacteriaceae bacterium “ARUP UnID261”101
Corynebacteriaceae bacterium “ARUP UnID268”110
Corynebacterium afermentans110
Corynebacterium confusum101
Corynebacterium macginleyi101
Corynebacterium massiliense101
Corynebacterium riegelii101
Corynebacterium simulans101
Corynebacterium singulare110
Corynebacterium sp. “ARUP UnID231”110
Corynebacterium sp. “ARUP UnID60”110
Corynebacterium sp. 2012257588110
Corynebacterium sp. 2012259355110
Corynebacterium sp. 59614101
Corynebacterium sp. MOLA 35101
Corynebacterium sp. NML90-0020110
Corynebacterium sp. S504101
Dermabacter sp. AD186110
Pseudoclavibacter bifida101
Pseudoclavibacter faecalis110
uncultured bacterium clone JSC7-39101
Zimmermannella sp. “ARUP UnID673”101
Table A7. Distribution of the of the species as assessed with 16S rRNA gene sequencing over the age in decades of the assessed patients, ordered by number. Results are presented exactly as provided by the applied database, explaining the partly outdated nomenclature.
Table A7. Distribution of the of the species as assessed with 16S rRNA gene sequencing over the age in decades of the assessed patients, ordered by number. Results are presented exactly as provided by the applied database, explaining the partly outdated nomenclature.
SpeciesAge in Decades
0–10 11–20 21–30 31–40 41–50 51–60 61–70 71–80 81–90 90+Total
Corynebacterium sp. “Smarlab Biomol”452212168144067
Corynebacterium glucuronolyticum3332510790042
Corynebacterium pseudogenitalium432134273029
Actinomyces sp. “ARUP UnID60”120267530026
Not identified010318153022
Actinotignum schaalii100214333118
Actinomyces turicensis321401240017
Corynebacterium sp. 707471/2012010014132012
Corynebacterium aurimucosum000114131011
Actinobaculum sp. V04 257809/08000010450010
Alloscardovia omnicolens01112202009
Corynebacterium sp.01112120109
Corynebacterium sp. ATCC 693100200511009
Actinomyces sp. 13-60500011501008
Corynebacterium amycolatum01001103107
Actinomyces radingae00002013006
Actinomyces sp. SD103000110005
Corynebacterium sp. “ARUP UnID281”01002200005
Corynebacterium sp. NML96-008501000211005
Corynebacterium sp. R-4586500011111005
Corynebacterium tuberculostearicum01100012005
Actinomyces europaeus00000012014
Actinomyces neuii LCDC 00000102104
Actinomyces urogenitalis10012000004
Corynebacterium imitans00201000014
Corynebacterium sp. 3159520100000014
Corynebacterium sp. canine oral taxon 424, OH 97700002200004
bacterium str. Rauti10001010003
Corynebacterium jeikeium00011001003
Corynebacterium minutissimum01000200003
Corynebacterium sp. “ARUP UnID245”00000021003
Actinomyces sp. 2234/0410000001002
Brevibacterium paucivorans00000002002
Brevibacterium sp. TSW19BA701000001002
Corynebacterium coyleae00000200002
Corynebacterium sp. M3T9B301000100002
Corynebacterium sp. R60300011000002
Corynebacterium urealyticum00000101002
Corynebacterium ureicelerivorans00000110002
Corynebacterium xerosis10010000002
Dermabacter hominis00001010002
Actinobaculum massiliense00000100001
Actinomyces hominis00000001001
Actinomyces sp. 13-11410000000001
Actinomyces sp. S5-BM900000001001
Arthrobacter albus00001000001
Arthrobacter cumminsii00000100001
Bacillus sp. PD1B00000010001
Corynebacteriaceae bacterium “ARUP UnID261”00000001001
Corynebacteriaceae bacterium “ARUP UnID268”00000010001
Corynebacterium afermentans00000100001
Corynebacterium confusum00000000101
Corynebacterium macginleyi00000100001
Corynebacterium massiliense00000010001
Corynebacterium riegelii00000100001
Corynebacterium simulans00000100001
Corynebacterium singulare00000100001
Corynebacterium sp. “ARUP UnID231”01000000001
Corynebacterium sp. “ARUP UnID60”00000100001
Corynebacterium sp. 201225758810000000001
Corynebacterium sp. 201225935500001000001
Corynebacterium sp. 5961400001000001
Corynebacterium sp. MOLA 3500000100001
Corynebacterium sp. NML90-002000010000001
Corynebacterium sp. S50400000100001
Dermabacter sp. AD18600000001001
Pseudoclavibacter bifida00001000001
Pseudoclavibacter faecalis00000000101
uncultured bacterium clone JSC7-3901000000001
Zimmermannella sp. “ARUP UnID673”00000001001

References

  1. Aragón, I.M.; Herrera-Imbroda, B.; Queipo-Ortuño, M.I.; Castillo, E.; Del Moral, J.S.; Gómez-Millán, J.; Yucel, G.; Lara, M.F. The Urinary Tract Microbiome in Health and Disease. Eur. Urol. Focus 2018, 4, 128–138. [Google Scholar] [CrossRef] [PubMed]
  2. Santiago-Rodriguez, T.M.; Ly, M.; Bonilla, N.; Pride, D.T. The human urine virome in association with urinary tract infections. Front. Microbiol. 2015, 6, 14. [Google Scholar] [CrossRef] [PubMed]
  3. Löffler, F. Untersuchungen über die Bedeutung der Mikroorganismen für die Entstehung der Diphtherie beim Menschen: Bei der Taube und beim Kalbe. Mitt. Kais. Gesundheitsamt 1884, 2, 421–499. [Google Scholar]
  4. Ulett, G.C.; Totsika, M.; Schaale, K.; Carey, A.J.; Sweet, M.J.; Schembri, M.A. Uropathogenic Escherichia coli virulence and innate immune responses during urinary tract infection. Curr. Opin. Microbiol. 2013, 16, 100–107. [Google Scholar] [CrossRef] [PubMed]
  5. Schubert, S.; Podschun, R.; Gatermann, S.; Fünfstück, R.; Naber, K.G.; Schimanski, S.; Wagenlehner, F. MiQ 02 Harnwegsinfektionen 3. Auflage 2020; Elsevier: München, Germany, 2020; pp. 1–82. [Google Scholar]
  6. Yin, P.; Kiss, A.; Leis, J.A. Urinalysis Orders Among Patients Admitted to the General Medicine Service. JAMA Intern. Med. 2015, 175, 1711–1713. [Google Scholar] [CrossRef]
  7. Lee, M.J.; Kim, M.; Kim, N.H.; Kim, C.J.; Song, K.H.; Choe, P.G.; Park, W.B.; Bang, J.H.; Kim, E.S.; Park, S.W.; et al. Why is asymptomatic bacteriuria overtreated?: A tertiary care institutional survey of resident physicians. BMC Infect. Dis. 2015, 15, 289. [Google Scholar] [CrossRef] [PubMed]
  8. Cope, M.; Cevallos, M.E.; Cadle, R.M.; Darouiche, R.O.; Musher, D.M.; Trautner, B.W. Inappropriate treatment of catheter-associated asymptomatic bacteriuria in a tertiary care hospital. Clin. Infect. Dis. 2009, 48, 1182–1188. [Google Scholar] [CrossRef]
  9. Fok, C.; Fitzgerald, M.P.; Turk, T.; Mueller, E.; Dalaza, L.; Schreckenberger, P. Reflex testing of male urine specimens misses few positive cultures may reduce unnecessary testing of normal specimens. Urology 2010, 75, 74–76. [Google Scholar] [CrossRef]
  10. Jones, C.W.; Culbreath, K.D.; Mehrotra, A.; Gilligan, P.H. Reflect urine culture cancellation in the emergency department. J. Emerg. Med. 2014, 46, 71–76. [Google Scholar] [CrossRef]
  11. Mauch, H. Einfluss von Lagerung und Transport auf das Überlegen von Infektionserregern. Bedeutung für eine schnelle mikrobiologische Diagnostik, die Ökonomie und den Patienten. Mikrobiologie 2008, 18, 200–204. [Google Scholar]
  12. Kogan, M.I.; Naboka, Y.L.; Ibishev, K.S.; Gudima, I.A.; Naber, K.G. Human urine is not sterile-shift of paradigm. Urol. Int. 2015, 94, 445–452. [Google Scholar] [CrossRef] [PubMed]
  13. Soriano, F.; Tauch, A. Microbiological and clinical features of Corynebacterium urealyticum: Urinary tract stones and genomics as the Rosetta Stone. Clin. Microbiol. Infect. 2008, 14, 632–643. [Google Scholar] [CrossRef] [PubMed]
  14. Stickler, D.J. Clinical complications of urinary catheters caused by crystalline biofilms: Something needs to be done. J. Intern. Med. 2014, 276, 120–129. [Google Scholar] [CrossRef] [PubMed]
  15. Devriese, L.A.; Riegel, P.; Hommez, J.; Vaneechoutte, M.; de Baere, T.; Haesebrouck, F. Identification of Corynebacterium glucuronolyticum strains from the urogenital tract of humans and pigs. J. Clin. Microbiol. 2000, 38, 4657–4659. [Google Scholar] [CrossRef] [PubMed]
  16. Furness, G.; Sambury, S.; Evangelista, A.T. Corynebacterium pseudogenitalium sp. nov. Commensals of the human male and female urogenital tracts. Investig. Urol. 1979, 16, 292–295. [Google Scholar]
  17. Gherardi, G.; Di Bonaventura, G.; Pompilio, A.; Savini, V. Corynebacterium glucuronolyticum causing genitourinary tract infection: Case report and review of the literature. IDCases 2015, 2, 56–58. [Google Scholar] [CrossRef] [PubMed]
  18. Lo, S.; Thiam, I.; Fall, B.; Ba-Diallo, A.; Diallo, O.F.; Diagne, R.; Dia, M.L.; Ka, R.; Sarr, A.M.; Sow, A.I. Urinary tract infection with Corynebacterium aurimucosum after urethroplasty stricture of the urethra: A case report. J. Med. Case Rep. 2015, 9, 156. [Google Scholar] [CrossRef] [PubMed]
  19. Salem, N.; Salem, L.; Saber, S.; Ismail, G.; Bluth, M.H. Corynebacterium urealyticum: A comprehensive review of an understated organism. Infect. Drug Resist. 2015, 8, 129–145. [Google Scholar] [PubMed]
  20. Vedel, G.; Toussaint, G.; Riegel, P.; Fouilladieu, J.L.; Billöet, A.; Poyart, C. Corynebacterium pseudogenitalium urinary tract infection. Emerg. Infect. Dis. 2006, 12, 355–356. [Google Scholar] [CrossRef]
  21. Könönen, E.; Wade, W.G. Actinomyces and related organisms in human infections. Clin. Microbiol. Rev. 2015, 28, 419–442. [Google Scholar] [CrossRef]
  22. Groeneveld, G.H.; Veldkamp, K.E.; van Dissel, J.T. Repetitive urinary tract infections and two prostatic masses: Prostatic soft tissue infection with Actinomyces neuii. Int. J. Infect. Dis. 2019, 86, 55–56. [Google Scholar] [CrossRef]
  23. Cai, X.; Peng, Y.; Li, M.; Qiu, Y.; Wang, Y.; Xu, L.; Hou, Q. Comparative genomic analyses of the clinically-derived Winkia strain NY0527: The reassignment of W. neuii subsp. neuii and W. neuii subsp. antitratus into two separate species and insights into their virulence characteristics. Front. Microbiol. 2023, 14, 1147469. [Google Scholar]
  24. Bank, S.; Jensen, A.; Hansen, T.M.; Søby, K.M.; Prag, J. Actinobaculum schaalii, a common uropathogen in elderly patients, Denmark. Emerg. Infect. Dis. 2010, 16, 76–80. [Google Scholar] [CrossRef] [PubMed]
  25. Greub, G.; Raoult, D. “Actinobaculum massiliae”, a new species causing chronic urinary tract infection. J. Clin. Microbiol. 2002, 40, 3938–3941. [Google Scholar] [CrossRef] [PubMed]
  26. Lotte, R.; Lotte, L.; Ruimy, R. Actinotignum schaalii (formerly Actinobaculum schaalii): A newly recognized pathogen-review of the literature. Clin. Microbiol. Infect. 2016, 22, 28–36. [Google Scholar] [CrossRef] [PubMed]
  27. Nielsen, H.L.; Søby, K.M.; Christensen, J.J.; Prag, J. Actinobaculum schaalii: A common cause of urinary tract infection in the elderly population. Bacteriological and clinical characteristics. Scand. J. Infect. Dis. 2010, 42, 43–47. [Google Scholar] [CrossRef] [PubMed]
  28. Pedersen, H.; Senneby, E.; Rasmussen, M. Clinical and microbiological features of Actinotignum bacteremia: A retrospective observational study of 57 cases. Eur. J. Clin. Microbiol. Infect. Dis. 2017, 36, 791–796. [Google Scholar] [CrossRef] [PubMed]
  29. Siegman-Igra, Y.; Kulka, T.; Schwartz, D.; Konforti, N. The significance of polymicrobial growth in urine: Contamination or true infection. Scand. J. Infect. Dis. 1993, 25, 85–91. [Google Scholar] [CrossRef] [PubMed]
  30. Siegman-Igra, Y. The significance of urine culture with mixed flora. Curr. Opin. Nephrol. Hypertens. 1994, 3, 656–659. [Google Scholar] [CrossRef]
  31. Grin, P.M.; Kowalewska, P.M.; Alhazzan, W.; Fox-Robichaud, A.E. Lactobacillus for preventing recurrent urinary tract infections in women. Meta-analysis. Can. J. Urol. 2013, 20, 6607–6614. [Google Scholar]
  32. Janulaitiene, M.; Paliulyte, V.; Grinceviciene, S.; Zakareviciene, J.; Vladisauskiene, A.; Marcinkute, A.; Pleckaityte, M. Prevalence and distribution of Gardnerella vaginalis subgroups in women with and without bacterial vaginosis. BMC Infect. Dis. 2017, 17, 394. [Google Scholar] [CrossRef] [PubMed]
  33. DAkkS Deutsche Akkreditierungsstelle Akkreditierung. Available online: https://imikro.med.uni-rostock.de/fileadmin/Institute/hygiene/Dokumente/Akkreditierung/akk_din15189.pdf (accessed on 27 March 2024).
  34. Baker, G.C.; Smith, J.J.; Cowan, D.A. Review and re-analysis of domain-specific 16S primers. J. Microbiol. Methods 2003, 55, 541–555. [Google Scholar] [CrossRef]
  35. Basic Local Alignment Search Tool. Available online: https://blast.ncbi.nlm.nih.gov/Blast.cgi (accessed on 27 March 2024).
  36. Yassin, A.F.; Spröer, C.; Pukall, R.; Sylvester, M.; Siering, C.; Schumann, P. Dissection of the genus Actinobaculum: Reclassification of Actinobaculum schaalii Lawson et al. 1997 and Actinobaculum urinale Hall et al. 2003 as Actinotignum schaalii gen. nov., comb. nov. and Actinotignum urinale comb. nov., description of Actinotignum sanguinis sp. nov. and emended descriptions of the genus Actinobaculum and Actinobaculum suis; and re-examination of the culture deposited as Actinobaculum massiliense CCUG 47753T (=DSM 19118T), revealing that it does not represent a strain of this species. Int. J. Syst. Evol. Microbiol. 2015, 65 Pt 2, 615–624. [Google Scholar]
  37. Bizzini, A.; Jaton, K.; Romo, D.; Bille, J.; Prod’hom, G.; Greub, G. Matrix-assisted laser desorption ionization-time of flight mass spectrometry as an alternative to 16S rRNA gene sequencing for identification of difficult-to-identify bacterial strains. J. Clin. Microbiol. 2011, 49, 693–696. [Google Scholar] [CrossRef]
  38. Freney, J.; Duperron, M.T.; Courtier, C.; Hansen, W.; Allard, F.; Boeufgras, J.M.; Monget, D.; Fleurette, J. Evaluation of API Coryne in comparison with conventional methods for identifying coryneform bacteria. J. Clin. Microbiol. 1991, 29, 38–41. [Google Scholar] [CrossRef] [PubMed]
  39. Funke, G.; Lawson, P.A.; Bernard, K.A.; Collins, M.D. Most Corynebacterium xerosis strains identified in the routine clinical laboratory correspond to Corynebacterium amycolatum. J. Clin. Microbiol. 1996, 34, 1124–1128. [Google Scholar] [CrossRef]
  40. Funke, G.; Renaud, F.N.; Freney, J.; Riegel, P. Multicenter evaluation of the updated and extended API (RAPID) Coryne database 2.0. J. Clin. Microbiol. 1997, 35, 3122–3126. [Google Scholar] [CrossRef]
  41. Hinic, V.; Lang, C.; Weisser, M.; Straub, C.; Frei, R.; Goldenberger, D. Corynebacterium tuberculostearicum: A potentially misidentified and multiresistant Corynebacterium species isolated from clinical specimens. J. Clin. Microbiol. 2012, 50, 2561–2567. [Google Scholar] [CrossRef] [PubMed]
  42. Leal, S.M., Jr.; Jones, M.; Gilligan, P.H. Clinical Significance of Commensal Gram-Positive Rods Routinely Isolated from Patient Samples. J. Clin. Microbiol. 2016, 54, 2928–2936. [Google Scholar] [CrossRef]
  43. Frickmann, H.; Weinreich, F.; Loderstädt, U.; Poppert, S.; Tannich, E.; Bull, J.; Kreikemeyer, B.; Barrantes, I. Metagenomic Sequencing for the Diagnosis of Plasmodium spp. with Different Levels of Parasitemia in EDTA Blood of Malaria Patients-A Proof-of-Principle Assessment. Int. J. Mol. Sci. 2022, 23, 11150. [Google Scholar] [CrossRef]
  44. Hahn, A.; Podbielski, A.; Meyer, T.; Zautner, A.E.; Loderstädt, U.; Schwarz, N.G.; Krüger, A.; Cadar, D.; Frickmann, H. On detection thresholds-a review on diagnostic approaches in the infectious disease laboratory and the interpretation of their results. Acta Trop. 2020, 205, 105377. [Google Scholar] [CrossRef] [PubMed]
  45. Kalantar, K.L.; Carvalho, T.; de Bourcy, C.F.A.; Dimitrov, B.; Dingle, G.; Egger, R.; Han, J.; Holmes, O.B.; Juan, Y.F.; King, R.; et al. IDseq-An open source cloud-based pipeline and analysis service for metagenomic pathogen detection and monitoring. Gigascience 2020, 9, giaa111. [Google Scholar] [CrossRef] [PubMed]
  46. Wang, D. Metagenomics Databases for Bacteria. Methods Mol. Biol. 2023, 2649, 55–67. [Google Scholar] [PubMed]
  47. Kannan, S.; Sharma, S.; Ciufo, S.; Clark, K.; Turner, S.; Kitts, P.A.; Schoch, C.L.; DiCuccio, M.; Kimchi, A. Collection and curation of prokaryotic genome assemblies from type strains at NCBI. Int. J. Syst. Evol. Microbiol. 2023, 73, 005707. [Google Scholar] [CrossRef] [PubMed]
  48. Schäffer, A.A.; McVeigh, R.; Robbertse, B.; Schoch, C.L.; Johnston, A.; Underwood, B.A.; Karsch-Mizrachi, I.; Nawrocki, E.P. Ribovore: Ribosomal RNA sequence analysis for GenBank submissions and database curation. BMC Bioinform. 2021, 22, 400. [Google Scholar] [CrossRef] [PubMed]
  49. Sarkonen, N.; Könönen, E.; Summanen, P.; Könönen, M.; Jousimies-Somer, H. Phenotypic identification of Actinomyces and related species isolated from human sources. J. Clin. Microbiol. 2001, 39, 3955–3961. [Google Scholar] [CrossRef]
  50. Hansen, J.M.; Fjeldsøe-Nielsen, H.; Sulim, S.; Kemp, M.; Christensen, J.J. Actinomyces species: A danish survey on human infections and microbiological characteristics. Open Microbiol. J. 2009, 3, 113–120. [Google Scholar] [CrossRef] [PubMed]
  51. Bank, S.; Hansen, T.M.; Søby, K.M.; Lund, L.; Prag, J. Actinobaculum schaalii in urological patients, screened with real-time polymerase chain reaction. Scand. J. Urol. Nephrol. 2011, 45, 406–410. [Google Scholar] [CrossRef]
  52. Belmares, J.; Detterline, S.; Pak, J.B.; Parada, J.P. Corynebacterium endocarditis species-specific risk factors and outcomes. BMC Infect. Dis. 2007, 7, 4. [Google Scholar] [CrossRef]
  53. Carvalho, R.V.; Lima, F.F.D.S.; Santos, C.S.D.; Souza, M.C.; Silva, R.S.D.; Mattos-Guaraldi, A.L. Central venous catheter-related infections caused by Corynebacterium amycolatum and other multiresistant non-diphtherial corynebacteria in paediatric oncology patients. Braz. J. Infect. Dis. 2018, 22, 347–351. [Google Scholar] [CrossRef]
  54. Stamm, W.E.; Tompkins, L.S.; Wagner, K.F.; Counts, G.W.; Thomas, E.D.; Meyers, J.D. Infection due to Corynebacterium species in marrow transplant patients. Ann. Intern. Med. 1979, 91, 167–173. [Google Scholar] [CrossRef] [PubMed]
  55. Bučević Popović, V.; Šitum, M.; Chow, C.T.; Chan, L.S.; Roje, B.; Terzić, J. The urinary microbiome associated with bladder cancer. Sci. Rep. 2018, 8, 12157. [Google Scholar] [CrossRef]
  56. Kramer, H.; Kuffel, G.; Thomas-White, K.; Wolfe, A.J.; Vellanki, K.; Leehey, D.J.; Bansal, V.K.; Brubaker, L.; Flanigan, R.; Koval, J.; et al. Diversity of the midstream urine microbiome in adults with chronic kidney disease. Int. Urol. Nephrol. 2018, 50, 1123–1130. [Google Scholar] [CrossRef]
  57. Olsen, A.B.; Andersen, P.K.; Bank, S.; Søby, K.M.; Lund, L.; Prag, J. Actinobaculum schaalii, a commensal of the urogenital area. BJU Int. 2013, 112, 394–397. [Google Scholar] [CrossRef]
  58. Sánchez-Martín, F.M.; López-Martínez, J.M.; Kanashiro-Azabache, A.; Moncada, E.; Angerri-Feu, O.; Millán-Rodríguez, F.; Villavicencio-Mavrich, H. Corinebacterium urealyticum: Increased incidence of infection and encrusted uropathy. Actas Urológicas Españolas 2016, 40, 102–107. [Google Scholar] [CrossRef] [PubMed]
  59. Andersen, L.B.; Bank, S.; Hertz, B.; Søby, K.M.; Prag, J. Actinobaculum schaalii, a cause of urinary tract infections in children? Acta Paediatr. 2012, 101, e232–e234. [Google Scholar] [CrossRef] [PubMed]
  60. Zimmermann, P.; Berlinger, L.; Liniger, B.; Grunt, S.; Agyeman, P.; Ritz, N. Actinobaculum schaalii an emerging pediatric pathogen? BMC Infect. Dis. 2012, 12, 201. [Google Scholar] [CrossRef]
  61. Bossuyt, P.M.; Reitsma, J.B.; Bruns, D.E.; Gatsonis, C.A.; Glasziou, P.P.; Irwig, L.; Lijmer, J.G.; Moher, D.; Rennie, D.; de Vet, H.C.; et al. STARD 2015: An updated list of essential items for reporting diagnostic accuracy studies. BMJ 2015, 351, h5527. [Google Scholar] [CrossRef]
Table 1. Diagnostic flowchart as applied for the study. Applied diagnostic strategies are color-coded in blue, diagnostic results leading to subsequent procedures are shown in green in case of conclusive results as well as in yellow in case of non-conclusive results, and diagnostic results leading to discarding of diagnostic materials are shown in red.
Table 1. Diagnostic flowchart as applied for the study. Applied diagnostic strategies are color-coded in blue, diagnostic results leading to subsequent procedures are shown in green in case of conclusive results as well as in yellow in case of non-conclusive results, and diagnostic results leading to discarding of diagnostic materials are shown in red.
Urine sample for diagnostic urinary culture from patients with clinical suspicion of urinary tract infection
2 days of incubation ± subsequent sub-culturing of colonies suspected of containing Gram-positive rod-shaped bacteria4 days of incubation ± subsequent sub-culturing of colonies suspected of containing Gram-positive rod-shaped bacteria
Gram staining
Gram-negative bacteriaGram-positive cocciGram-positive rod-shaped bacteriaCoccoid Gram-positive bacteria Non-conclusive result
DiscardedMatrix-assisted laser desorption–ionization time-of-flight mass spectrometry
OthersGram-positive rod-shaped bacteria Non-conclusive result
DiscardedAPI (analytical profile index) for coryneform rod-shaped bacteria
16S rRNA gene sequencing
OthersGram-positive rod-shaped bacteria
DiscardedFreeze-storage for potential re-testing
Table 2. Characterization of the study population consisting of inpatients with suspicion of urinary tract infection.
Table 2. Characterization of the study population consisting of inpatients with suspicion of urinary tract infection.
Number of Urine Sample Stratified by Age GroupsMale (n)Female (n)Total (n)
Total (n)6784921170
0–10 years (n)563389
11–20 years (n)434184
21–30 years (n)182543
31–40 years (n)283159
41–50 years (n)6960129
51–60 years (n)129100229
61–70 years (n)10457161
71–80 years (n)18296278
81–90 years (n)493887
90+ years (n)01111
n = total number.
Table 3. Matches and mismatches between the applied analytic approaches.
Table 3. Matches and mismatches between the applied analytic approaches.
Confirmation of mass-spectrometry-based or biochemistry-based results by 16S rRNA gene sequencing
Confirmation of MALDI-TOF-MS (Saramis database) results by 16S rRNA gene sequencingConfirmation of MALDI-TOF-MS (Myla database) results by 16S rRNA gene sequencingConfirmation of biochemistry (API Coryne) results by 16S rRNA gene sequencing
At the genus level, n/n (%)At the species level, n/n (%)At the genus level, n/n (%)At the species level, n/n (%)At the genus level, n/n (%)At the species level, n/n (%)
Gram-positive rod-shaped bacteria75/115 (65.2%)25/115 (21.7%)159/302 (52.6%)88/302 (29.1%)212/412 (51.5%)59/412 (14.3%)
Non-conclusive 16S rRNA gene sequencing results15/115 (13.0%)6/302 (2.0%)0/412 (-) *
Matching of mass-spectrometry-based or biochemistry-based results with 16S rRNA gene sequencing if the latter is applied as a reference standard
Matching of MALDI-TOF-MS (Saramis database) with 16S rRNA gene sequencingMatching of MALDI-TOF-MS (Myla database) with 16S rRNA gene sequencingMatching of biochemistry (API Coryne) with 16S rRNA gene sequencing
At the genus level, n/n (%)At the species level, n/n (%)At the genus level, n/n (%)At the species level, n/n (%)At the genus level, n/n (%)At the species level, n/n (%)
Corynebacterium spp.84/254 (33.1%)15/254 (5.9%)181/254 (71.3%)17/254 (6.7%)172/254 (67.7%)40/254 (15.7%)
Actinomyces/Winkia spp.10/79 (12.7%)3/79 (3.8%)60/79 (75.9%)23/79 (29.1%)36/79 (45.6%)18/79 (22.8%)
Actinobaculum/Actinotignum spp.6/29 (20.7%)2/29 (6.9%)0/29 (-)0/29 (-)0/29 (-)0/29 (-)
* Of note, two API Coryne results were matched by 16S rRNA gene sequencing results on family level only.
Table 4. Distribution of the detections of Gram-positive rod-shaped bacteria over the various provided urine sampling approaches, ordered by number.
Table 4. Distribution of the detections of Gram-positive rod-shaped bacteria over the various provided urine sampling approaches, ordered by number.
Distribution of Gram-Positive Rod-Shaped Bacteria over the Different Urine Sampling Approaches
Urine Sampling ApproachNumber (n) of Assessed SamplesNumber (n) of Detections of Gram-Positive Rod-Shaped BacteriaProportion (%) of Samples with Growth of Gram-Positive Rod-Shaped Bacteria
Mid-stream urine79535845.0%
Urine from an Indwelling urinary catheter14742.7%
Unknown urine sampling approach1023837.3%
Urine collected in a pouch38718.4%
Urine from an intermittent urinary catheter200-
Urine from a urinary catheter without further information180-
Urine from an entero-vesical fistula1815.6%
Urine from an ileal conduit1317.7%
Urine collected in a pot10110.0%
Urine collected via bladder puncture60-
Urine collected via puncture of the renal pelvis20-
First jet urine11100.0%
Distribution of Corynebacterium spp., Actinomyces/Winkia spp. and Actinotignum/Actinobaculum spp. over Major Clusters of Different Urine Sampling Approaches
GenusMid-Stream UrineUrine from a CatheterOther Types of Urine Sampling
Corynebacterium223 (54.1%)1 (0.2%)30 (7.3%)
Actinomyces/Winkia65 (15.8%)1 (0.2%)13 (3.2%)
Actinotignum/Actinobaculum25 (6.1%)1 (0.2%)3 (0.7%)
Table 5. Distribution of Corynebacterium spp., Actinomyces/Winkia spp. and Actinotignum/Actinobaculum spp. by female and male sex.
Table 5. Distribution of Corynebacterium spp., Actinomyces/Winkia spp. and Actinotignum/Actinobaculum spp. by female and male sex.
GenusMale (n)Female (n)
Corynebacterium6064
Actinomyces/Winkia2216
Actinotignum/Actinobaculum87
Table 6. Distribution of Gram-positive rod-shaped bacteria over the various age in decades of the assessed patients.
Table 6. Distribution of Gram-positive rod-shaped bacteria over the various age in decades of the assessed patients.
Age in Decades
0–1011–2021–3031–4041–5051–6061–7071–8081–90 90+
Number of urine samples898443591292291612788711
Proportion of 1170 urine samples7.67.23.75.011.019.613.823.87.40.9
Number of Gram-positive rod-shaped bacteria2431162655985186214
Average number needed to detect a Gram-positive rod-shaped bacterium3.72.72.72.32.32.33.23.24.12.8
Table 7. Distribution of Corynebacterium spp., Actinomyces/Winkia spp. and Actinotignum/Actinobaculum spp. by age decade of the assessed patients.
Table 7. Distribution of Corynebacterium spp., Actinomyces/Winkia spp. and Actinotignum/Actinobaculum spp. by age decade of the assessed patients.
Age Decade in Years0–1011–2021–3031–4041–5051–6061–7071–8081–90>90
Number of urine assessments898443591292291612788711
Number of Corynebacterium spp. detections1520141235673048132
Number of Corynebacterium spp. detections per urine assessment0.170.240.330.200.270.290.190.170.150.18
Number of Actinomyces/Winkia spp. detections77181216101811
Number of Actinomyces/Winkia spp. detections per urine assessment0.080.080.020.140.090.070.060.060.010.09
Number of Actinotignum/Actinobaculum spp. detections1002257831
Number of Actinotignum/Actinobaculum spp. detections per urine assessment0.010.000.000.030.020.020.040.030.030.09
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Frickmann, H.; Schwinge, K.; Podbielski, A.; Warnke, P. Preanalytical, Analytical and Postanalytical Analyses on Corynebacterium spp. and Actinomycetaceae in Urine Samples of Patients with Suspected Urinary Tract Infection—A Hypothesis-Forming Observational Study. Diagnostics 2024, 14, 746. https://doi.org/10.3390/diagnostics14070746

AMA Style

Frickmann H, Schwinge K, Podbielski A, Warnke P. Preanalytical, Analytical and Postanalytical Analyses on Corynebacterium spp. and Actinomycetaceae in Urine Samples of Patients with Suspected Urinary Tract Infection—A Hypothesis-Forming Observational Study. Diagnostics. 2024; 14(7):746. https://doi.org/10.3390/diagnostics14070746

Chicago/Turabian Style

Frickmann, Hagen, Kerstin Schwinge, Andreas Podbielski, and Philipp Warnke. 2024. "Preanalytical, Analytical and Postanalytical Analyses on Corynebacterium spp. and Actinomycetaceae in Urine Samples of Patients with Suspected Urinary Tract Infection—A Hypothesis-Forming Observational Study" Diagnostics 14, no. 7: 746. https://doi.org/10.3390/diagnostics14070746

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