Advances in Medical Microbiology

A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Medical Microbiology".

Deadline for manuscript submissions: 30 September 2024 | Viewed by 4045

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Guest Editor
Department of Biochemical Sciences for Health, University of Milan, Milan, Italy
Interests: microbiota and probiotics; prosthetic and joint infections; biofilm implant related infections; osteomyelitis; diagnosis for bone-joint infections; antimicrobials and antimicrobial devices
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Special Issue Information

Dear Colleagues,

This Special Issue aims to provide a comprehensive overview of state-of-the-art medical microbiology. We encourage researchers from related fields to contribute papers highlighting the latest developments in medical microbiology or to invite relevant experts and colleagues to do so. This Special Issue will publish full research articles and comprehensive reviews.

Prof. Dr. Lorenzo Drago
Guest Editor

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Published Papers (7 papers)

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Research

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8 pages, 425 KiB  
Communication
Use of PCR Cycle Threshold and Clinical Interventions to Aid in the Management of Pediatric Clostridioides difficile Patients
by Mohammed Suleiman, Patrick Tang, Omar Imam, Princess Morales, Diyna Altrmanini, Kelli L. Barr, Jill C. Roberts and Andrés Pérez-López
Microorganisms 2024, 12(6), 1181; https://doi.org/10.3390/microorganisms12061181 - 11 Jun 2024
Viewed by 142
Abstract
Better diagnostic tools are needed to improve the diagnosis of Clostridioides difficile infections (CDI) and reduce the overtreatment of colonized children. In this study, we evaluated two polymerase chain reaction (PCR) assays (Cepheid GeneXpert C. difficile and the Gastroenteritis PCR Panel by QIAstat-Dx) [...] Read more.
Better diagnostic tools are needed to improve the diagnosis of Clostridioides difficile infections (CDI) and reduce the overtreatment of colonized children. In this study, we evaluated two polymerase chain reaction (PCR) assays (Cepheid GeneXpert C. difficile and the Gastroenteritis PCR Panel by QIAstat-Dx) as a standalone method in combination with the PCR cycle threshold (Ct) value in positive samples to predict the presence of free toxins. We also evaluated the clinical impact of reporting toxin production results and provided comments alongside the PCR results in our pediatric population. PCR-positive stool samples from pediatric patients (aged 2 to 18 years old) were included in our study and tested for the presence of toxins A and B using the C. difficile Quik Chek Complete kit. For the clinical intervention, the CDI treatment rates 6 months pre- and post-intervention were compared. The use of PCR Ct value showed excellent sensitivity (100%) at a Ct value cutoff of 26.1 and 27.2 using the Cepheid GeneXpert C. difficile and the Gastroenteritis PCR Panel by QIAstat-Dx, respectively, while the toxin test showed inferior sensitivity of 64% in the PCR-positive samples. In addition, CDI treatment rates were decreased by 23% post-intervention. The results of our study suggest that nucleic acid amplification test (NAAT) assays supplemented by the use of PCR Ct value for positive samples can be used as standalone tests to differentiate CDI from colonization. Furthermore, the reporting of toxin production along with the PCR results can help reduce the unnecessary treatment of colonized children. Full article
(This article belongs to the Special Issue Advances in Medical Microbiology)
13 pages, 245 KiB  
Article
Nocardiosis in Solid Organ Transplant Recipients: 10-Year Single Center Experience and Review of Literature
by Julia Bini Viotti, Jacques Simkins, John M. Reynolds, Gaetano Ciancio, Giselle Guerra, Lilian Abbo and Shweta Anjan
Microorganisms 2024, 12(6), 1156; https://doi.org/10.3390/microorganisms12061156 - 6 Jun 2024
Viewed by 258
Abstract
Solid organ transplant recipients (SOTRs) are at an increased risk of nocardiosis, a rare but life-threatening opportunistic infection. Universal PCP prophylaxis with trimethoprim–sulfamethoxazole (TMP-SMX) is used at our center, which is active in vitro against most species of the Nocardia genus and may [...] Read more.
Solid organ transplant recipients (SOTRs) are at an increased risk of nocardiosis, a rare but life-threatening opportunistic infection. Universal PCP prophylaxis with trimethoprim–sulfamethoxazole (TMP-SMX) is used at our center, which is active in vitro against most species of the Nocardia genus and may have a role in preventing early infections. This is a single-center retrospective cohort study of nocardiosis in adult SOTRs at a large transplant center between January 2012 and June 2022, with comprehensive review of literature. Out of 6179 consecutive cases, 13 (0.2%) were diagnosed with nocardiosis. The patients were predominantly male (76.9%) and kidney transplant recipients (62%). Infection was diagnosed at median of 8.8 months (range, 3.7–98) after transplant. Patients were followed for a median of 457 days (range 8–3367). Overall mortality within one year after diagnosis was 46% (6/13), of which 17% (1/6) of deaths was attributable to Nocardia infection. No recurrence was reported. Nocardia infections were noted in a small proportion of our SOTRs and carried significant morbidity and mortality. TMP-SMX prophylaxis may be protective in some cases given low incidence of cases. Full article
(This article belongs to the Special Issue Advances in Medical Microbiology)
6 pages, 189 KiB  
Communication
Antibiotic Resistance Profiles in Eye Infections: A Local Concern with a Retrospective Focus on a Large Hospital in Northern Italy
by Lorenzo Drago, Vincenzo Minasi, Andrea Lembo, Angela Uslenghi, Sofia Benedetti, Matteo Covi, Paolo Nucci and Loredana Deflorio
Microorganisms 2024, 12(5), 984; https://doi.org/10.3390/microorganisms12050984 - 14 May 2024
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Abstract
The emergence of antibiotic resistance poses a significant threat to public health worldwide, affecting various medical fields, including ophthalmology. Eye infections, ranging from conjunctivitis to more severe conditions like keratitis, are commonly treated with antibiotics. However, the misuse and overuse of these drugs [...] Read more.
The emergence of antibiotic resistance poses a significant threat to public health worldwide, affecting various medical fields, including ophthalmology. Eye infections, ranging from conjunctivitis to more severe conditions like keratitis, are commonly treated with antibiotics. However, the misuse and overuse of these drugs have led to the development of resistant strains of bacteria, allowing traditional treatments ineffective. This paper aims to examine the current situation of antibiotic resistance in eye infections globally, with a specific focus on a large group of hospitals located in Milan (Italy) with considerable experience in cataract and cornea surgery as well as in retinopathy. The results of the study show the prevalence of Gram-positives in the tested samples and a low resistance of fluoroquinolones and glycopeptides. The results also highlight the need to implement sample collection methods for ocular infections, as the quantity of positive samples is rather low compared to the total number of samples. In conclusion, the study, although with limited data, shows that resistance to aminoglycosides and cephalosporins is a situation to be monitored. These data also show the critical need to improve and guide the biological sample collection modalities in order to make the diagnosis more reliable. Full article
(This article belongs to the Special Issue Advances in Medical Microbiology)
17 pages, 937 KiB  
Article
Prospective Longitudinal Study of Dynamics of Human Papillomavirus 6 and 11 Infection in Anogenital Hairs and Eyebrows of Male Patients with Anogenital Warts and Age-Matched Controls
by Vesna Tlaker, Lea Hošnjak, Mateja Kolenc, Tomaž Mark Zorec, Boštjan Luzar, Marko Potočnik, Jovan Miljković, Katja Seme and Mario Poljak
Microorganisms 2024, 12(3), 466; https://doi.org/10.3390/microorganisms12030466 - 25 Feb 2024
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Abstract
To better understand the natural history of anogenital warts (AGWs) and the dynamics of HPV6/11 infection in regional hairs, 32 newly diagnosed male patients with AGWs and 32 age-matched healthy controls were closely followed. During enrollment and six follow-up visits (every 2.6 months), [...] Read more.
To better understand the natural history of anogenital warts (AGWs) and the dynamics of HPV6/11 infection in regional hairs, 32 newly diagnosed male patients with AGWs and 32 age-matched healthy controls were closely followed. During enrollment and six follow-up visits (every 2.6 months), 43 AGW tissues and 1232 anogenital and eyebrow hair samples were collected. This is the closest longitudinal monitoring of AGW patients to date. Patients were treated according to standards of care. The HPV6/11 prevalence was 19.9% in the patients’ hair samples (HPV6 B1 in 53.1%) and 0% in the controls. The highest HPV6/11 prevalence was found in pubic hairs (29.0%) and the lowest in eyebrows (7.1%). The odds of having HPV6/11-positive hairs increased with smoking, shaving the anogenital region, and age. A close association between HPV6/11 presence in hairs and clinically visible AGWs was observed. The proportion of patients with visible AGWs and HPV6/11-positive hairs declined during follow-up with similar trends. No particular HPV6/11 variant was linked with an increased AGW recurrence, but the sublineage HPV6 B1 showed significantly higher clearance from hairs. Despite treatment, 78.1% and 62.5% of the AGW patients experienced one and two or more post-initial AGW episodes, respectively. The patients with HPV6/11-positive hairs or visible AGWs at a preceding visit demonstrated substantially higher odds of presenting with visible AGWs at a subsequent visit. Full article
(This article belongs to the Special Issue Advances in Medical Microbiology)
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Review

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23 pages, 3802 KiB  
Review
The Role of Bacteria in Central Nervous System Tumors: Opportunities and Challenges
by Rui Zhang, Xueying Li and Si Zhang
Microorganisms 2024, 12(6), 1053; https://doi.org/10.3390/microorganisms12061053 - 23 May 2024
Viewed by 384
Abstract
Tumors of the central nervous system (CNS) are severe and refractory diseases with poor prognosis, especially for patients with malignant glioblastoma and brain metastases. Currently, numerous studies have explored the potential role of bacteria and intestinal flora in tumor development and treatment. Bacteria [...] Read more.
Tumors of the central nervous system (CNS) are severe and refractory diseases with poor prognosis, especially for patients with malignant glioblastoma and brain metastases. Currently, numerous studies have explored the potential role of bacteria and intestinal flora in tumor development and treatment. Bacteria can penetrate the blood–brain barrier (BBB), targeting the hypoxic microenvironment at the core of tumors, thereby eliminating tumors and activating both the innate and adaptive immune responses, rendering them promising therapeutic agents for CNS tumors. In addition, engineered bacteria and derivatives, such as bacterial membrane proteins and bacterial spores, can also be used as good candidate carriers for targeted drug delivery. Moreover, the intestinal flora can regulate CNS tumor metabolism and influence the immune microenvironment through the “gut–brain axis”. Therefore, bacterial anti-tumor therapy, engineered bacterial targeted drug delivery, and intervention of the intestinal flora provide therapeutic modalities for the treatment of CNS tumors. In this paper, we performed a comprehensive review of the mechanisms and therapeutic practices of bacterial therapy for CNS tumors and discussed potential future research directions in this field. Full article
(This article belongs to the Special Issue Advances in Medical Microbiology)
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13 pages, 1569 KiB  
Review
Bacteria Living in Biofilms in Fluids: Could Chemical Antibiofilm Pretreatment of Culture Represent a Paradigm Shift in Diagnostics?
by Lorenzo Drago, Andrea Fidanza, Alessio Giannetti, Alessio Ciuffoletti, Giandomenico Logroscino and Carlo Luca Romanò
Microorganisms 2024, 12(2), 259; https://doi.org/10.3390/microorganisms12020259 - 26 Jan 2024
Viewed by 1071
Abstract
Biofilms are multicellular aggregates of bacteria immersed in an extracellular matrix that forms on various surfaces, including biological tissues and artificial surfaces. However, more and more reports point out the fact that even biological fluids and semifluid, such as synovial liquid, blood, urine, [...] Read more.
Biofilms are multicellular aggregates of bacteria immersed in an extracellular matrix that forms on various surfaces, including biological tissues and artificial surfaces. However, more and more reports point out the fact that even biological fluids and semifluid, such as synovial liquid, blood, urine, or mucus and feces, harbor “non-attached” biofilm aggregates of bacteria, which represent a significant phenomenon with critical clinical implications that remain to be fully investigated. In particular, biofilm aggregates in biological fluid samples have been shown to play a relevant role in bacterial count and in the overall accuracy of microbiological diagnosis. In line with these observations, the introduction in the clinical setting of fluid sample pretreatment with an antibiofilm chemical compound called dithiothreitol (DTT), which is able to dislodge microorganisms from their intercellular matrix without killing them, would effectively improve the microbiological yield and increase the sensitivity of cultural examination, compared to the current microbiological techniques. While other ongoing research continues to unveil the complexity of biofilm formation in biological fluids and its impact on infection pathogenesis and diagnosis, we here hypothesize that the routine use of a chemical antibiofilm pretreatment of fluid and semi-solid samples may lead to a paradigm shift in the microbiological approach to the diagnosis of biofilm-related infections and should be further investigated and eventually implemented in the clinical setting. Full article
(This article belongs to the Special Issue Advances in Medical Microbiology)
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Other

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6 pages, 655 KiB  
Case Report
Community-Acquired Solitary Brain Abscesses Caused by Hypervirulent Klebsiella pneumoniae in a Healthy Adult
by Joo-Hee Hwang, Jung Soo Park, Tae Won Bae, Jeong-Hwan Hwang and Jaehyeon Lee
Microorganisms 2024, 12(5), 894; https://doi.org/10.3390/microorganisms12050894 - 29 Apr 2024
Viewed by 514
Abstract
A 42-year-old man was admitted to the emergency room complaining of fever and headache. His cerebrospinal fluid showed a cloudy appearance, and his white blood cell count was elevated at 2460/mm3, with a predominance of neutrophils (81%), and abnormal protein and [...] Read more.
A 42-year-old man was admitted to the emergency room complaining of fever and headache. His cerebrospinal fluid showed a cloudy appearance, and his white blood cell count was elevated at 2460/mm3, with a predominance of neutrophils (81%), and abnormal protein and glucose levels (510.7 mg/dL and 5 mg/dL, respectively). A lobulated lesion with rim enhancement, suggestive of abscess, was detected through magnetic resonance imaging. Klebsiella pneumoniae was detected in nasopharyngeal swab and blood cultures. The capsular serotype of K. pneumoniae was K2 and the sequence type determined by multilocus sequence typing was 23. The hypervirulent phenotype was associated with multiple virulent genes, including rmpA, rmpA2, entB, ybtS, kfu, iucA, iutA, iroB mrkD, allS, peg-344, peg-589, and peg-1631. After six weeks of receiving appropriate antibiotics and exhibiting clinical resolution of the brain abscesses, the patient was discharged. We present the first reported case of a healthy community-dwelling adult with solitary brain abscesses, and no other invasive abscesses, related to hypervirulent K. pneumoniae. Full article
(This article belongs to the Special Issue Advances in Medical Microbiology)
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