Search Results (12)

Subclinical mastitis is a major but often overlooked constraint to dairy productivity, causing economic losses through reduced milk yield and quality. In Romania, comprehensive data on the bacterial etiology and antimicrobial resistance (AMR) of subclinical mastitis are limited. This study aimed to characterize the etiological agents and antimicrobial susceptibility profiles of major bacterial pathogens isolated from subclinical mastitis cases in dairy cows from Western Romania. Between 2021 and 2022, milk samples were collected from 117 lactating cows diagnosed with subclinical mastitis on three dairy farms. Bacterial isolation and differentiation were performed on ChromID^® CPS^® Elite Agar, and isolates were confirmed by standard biochemical tests. Antimicrobial susceptibility testing of Staphylococcus aureus and Escherichia coli isolates was conducted using the automated Vitek^®2 system, interpreted according to CLSI veterinary standards. Multidrug resistance (MDR) was defined as resistance to at least one agent in three or more antimicrobial classes. Bacterial growth occurred in 51 of 117 samples (43.6%). S. aureus subsp. aureus predominated (28.2%), followed by E. coli (4.3%), Klebsiella pneumoniae subsp. pneumoniae (2.3%), and Streptococcus uberis (2.3%). Mixed infections occurred in 6.0% of positive samples. Among S. aureus, the highest resistance rates were to fosfomycin (58.3%), penicillin (44.4%), clindamycin (44.4%), and tetracycline (41.7%), with 47.2% MDR isolates. E. coli showed resistance to amoxicillin/clavulanic acid (88.9%), ampicillin (55.6%), and cefotaxime (55.6%), with 66.6% MDR. S. aureus remains the leading cause of subclinical mastitis in Western Romania. The high MDR rates highlight the need for targeted antimicrobial stewardship, culture-based therapy, and continuous AMR monitoring under the “One Health” framework. Full article

The role of petting zoo animals in the dissemination of disease has been widely studied, yet understanding the potential reservoir of antimicrobial resistance (AMR) in these centres has not been explored in the United Kingdom (UK). To understand the carriage of AMR pathogens within petting zoos, this study aimed to identify AMR in E. coli and Staphylococcus intermedius group (SIG) isolated from faeces and skin, respectively, including selective cultures for ESBL-E. coli and methicillin-resistant staphylococci. Faecal samples and skin swabs were collected from 166 petted mammals across eight UK centres to recover E. coli and coagulase-positive staphylococci (CoPS), respectively, through enrichment culture methods, plating onto non-selective (tryptone bile-x agar, mannitol salt agar) and selective media (ESBL ChromID, mannitol salt agar with 6 mg/L oxacillin). Antimicrobial susceptibility was assessed using Kirby-Bauer disc diffusion, covering eight classes of antimicrobials. Antimicrobial usage records from the past 12-months were obtained from 7/8 centres. Overall, 145/166 faecal samples yielded 223 E. coli isolates, with an overall AMR prevalence of 42.6%. Thirteen E. coli isolates (from 8.5% of animals) were classified as multidrug-resistant. ESBL-producing E. coli were detected in 5/166 faecal samples. From 166 skin swabs, 84 yielded CoPS isolates, with S. aureus (n = 70), SIG (n = 13) and S. hyicus (n = 1) identified. Overall, 25.3% of SIG isolates exhibited resistance to at least one antimicrobial. Antimicrobial usage correlated positively with AMR prevalence for E. coli (p < 0.001), though was not associated with multidrug-resistance. This study demonstrates for the first time the presence of AMR within bacteria isolated from UK petting zoo animals, highlighting this reservoir of AMR bacteria. Full article

Yeasts of the Candida genus are part of the normal human microbiota but can cause infections (candidiasis) under certain conditions. While Candida albicans remains the most common etiological agent, the prevalence of non-albicans Candida species—such as C. glabrata, C. tropicalis, C. krusei, C. parapsilosis, C. kefyr, C. lusitaniae, and the emerging multidrug-resistant C. auris—has been increasing. Effective treatment of candidiasis requires rapid and accurate identification of the causative species, particularly due to species-specific antifungal agent resistance patterns. The aim of this study was to evaluate the usefulness of five chromogenic media for the differentiation of Candida species: BD CHROMagar Candida (Becton Dickinson), CHROM ID Candida (bioMérieux), CHROMAgar Candida Plus (CHROMAgar France, Biomaxima), CHROMAgar Candida Plus (GRASO Biotech), and Brilliance Candida Agar (OXOID). A total of 175 strains from the following species were tested: C. albicans, C. parapsilosis, C. dubliniensis, C. lusitaniae, C. tropicalis, C. glabrata, C. kefyr, C. krusei, and C. auris. Species identification was confirmed by MALDI-TOF mass spectrometry using the MALDI Biotyper system (Bruker). Colony morphology, especially color characteristics, was assessed on each medium. The morphological features of most Candida species were consistent with the manufacturer’s descriptions and allowed for presumptive species-level identification. However, some species showed reproducible but previously undescribed morphological traits, including variations in colony shade. Notably, C. auris could not be reliably identified using BD, bioMérieux, or OXOID media. In conclusion, while chromogenic media are a helpful preliminary diagnostic tool, subtle differences in colony coloration can complicate interpretation. Diagnostic caution is recommended, and confirmatory methods such as MALDI-TOF remain essential for reliable identification, especially for emerging or less common Candida species. Full article

Antimicrobial resistance is a growing global threat, with surveillance providing essential information to control its spread and support rational treatment strategies. Klebsiella pneumoniae, a member of the Gram-negative Enterobacteriaceae family, frequently develops resistance mechanisms. This study analyzed 195 rectal swabs from companion and stray dogs in Santiago and São Nicolau (Cape Verde) and São Tomé and Príncipe, sampled during a neutering and deworming campaign conducted by Veterinary Without Borders Portugal, to detect extended-spectrum β-lactamase (ESBL)-producing bacteria. Samples were enriched and then cultured on ChromID^® ESBL agar, and resulting isolates were identified via MALDI-TOF MS. A total of 35 K. pneumoniae isolates were identified, of which 32 were confirmed as ESBL producers. Antimicrobial susceptibility testing showed 100% resistance to aztreonam, cefotaxime, cefpodoxime, and ceftaroline, and high resistance to cefepime (93.8%), ciprofloxacin (93.8%), and trimethoprim/sulfamethoxazole (90.6%). All isolates were considered multidrug-resistant but remained susceptible to cefoxitin, imipenem, and meropenem. The genes bla_CTX-M, bla_SHV, and bla_TEM were present in 96.9%, 65.6%, and 56.3% of the isolates, respectively. DNA fingerprinting revealed seven clusters, suggesting genetic diversity and strain dissemination across locations. These findings highlight the role of dogs as vectors for antimicrobial resistance dissemination, underscoring the need for continuous surveillance in both veterinary and human medicine. Full article

The presence of potentially pathogenic bacteria on veterinary clinic surfaces may be problematic. In this study, we collected swab samples (Fisherbrand, double transport swabs with Stuart’s liquid medium) and water samples from five veterinary rehabilitation clinics. Swabs and water samples were transported to a microbiology lab for processing. At the lab, swabs were used to inoculate Hardy’s Cdiff Banana Broth (for Clostridium difficile [Cdiff]) and five different types of bacterial growth media, including Hardy CHROM MRSA agar (methicillin-resistant Staphylococcus aureus [MRSA] and S. pseudintermedius [SIM]), mannitol salt agar (S. aureus [SA]), eosin methylene blue agar (enterics [ENT]), Pseudomonas isolation agar (Pseudomonas spp. [PS]), and tryptic soy agar [TSA] (non-specific). The most prominent presumptive species cultured was Cdiff (on nearly 55% of swabs). Bacillus spp. and enteric bacteria were encountered on nearly 35% of swabs, with MRSA and SIM on just over 10% of swabs. The most contaminated sample site was harnesses/life jackets used with the underwater treadmill (33% of swabs). The underwater treadmill water had total bacterial counts from 1,600 to 2,800 cfu/mL. Of all presumptive bacterial species detected, SIM tends to be more pathogenic for dogs. Targeted cleaning/disinfecting in these clinics could help reduce risks for both animals and caregivers utilizing these clinics. Full article

Five commercially available selective agar were evaluated regarding sensitivity and specificity to detect vancomycin-resistant Enterococcus (E.) faecium. Altogether 187 E. faecium strains were included, comprising 119 van-carrying strains (phenotypically vancomycin-resistant n = 105; phenotypically vancomycin-susceptible VVE-B n = 14) and 68 vancomycin-susceptible isolates. Limit of detection was calculated for each selective agar for pure cultures, stool suspensions and artificial rectal swabs. After 24-h incubation sensitivity ranged between 91.6% and 95.0%. It increased in 2 out of 5 agar after 48-h incubation. Specificity ranged between 94.1% and 100% and was highest after 24 h in 4 out of the 5 agar. Sensitivity of van-carrying phenotypically vancomycin-resistant strains was higher after 24 h (97.1–100%) and 48 h (99.1–100%) when compared to van-carrying strains that tested vancomycin-susceptible (50.0–57.1% after both incubation periods). Overall, chromID VRE, CHROMagar VRE and Brilliance VRE demonstrated the highest detection rates after 24 h. Detection rates of Chromatic VRE and VRESelect improved after 48 h. Adjustment of incubation time depending on the applied media may be advised. As detection of VVE-B was impeded with all selective agar, screening for vancomycin-resistant enterococci relying solely on selective media would not be recommended for critical clinical samples, but rather in combination with molecular methods to improve detection of these strains. Furthermore, stool samples were demonstrated to be superior to rectal swabs and should be favoured, if possible, in screening strategies. Full article

Acinetobacter baumannii (A. baumannii) is an opportunistic pathogen associated with nosocomial infections. In this study, 100 raw milk samples were collected from Qena, Egypt, and subjected to conventional and molecular assays to determine the presence of A. baumannii and investigate their antimicrobial resistance and biofilm formation. Our findings revealed that, among the 100 samples, Acinetobacter spp. were found in 13 samples based on CHROM agar results. We further characterized them using rpoB and 16S-23SrRNA sequencing and gyrB multiplex PCR analysis and confirmed that 9 out of the 13 Acinetobacter spp. isolates were A. baumannii and 4 were other species. The A. baumannii isolates were resistant to β-lactam drugs, including cefotaxime (44%), ampicillin-sulbactam and levofloxacin (33.3% for each), imipenem, meropenem and aztreonam (22.2% for each). We observed different antimicrobial resistance patterns, with a multi-antibiotic resistant (MAR) index ranging from 0.2 to 0.3. According to the PCR results, bla_OXA-51 and bla_OXA-23 genes were amplified in 100% and 55.5% of the A. baumannii isolates, respectively, while the bla_OXA-58 gene was not amplified. Furthermore, the metallo-β-lactamases (MBL) genes bla_IMP and bla_NDM were found in 11.1% and 22.2% of isolates, respectively, while bla_VIM was not amplified. Additionally, eight A. baumannii isolates (88.8%) produced black-colored colonies on Congo red agar, demonstrating their biofilm production capacity. These results showed that, besides other foodborne pathogens, raw milk should also be examined for A. baumannii, which could be a public health concern. Full article

Background: In the medical laboratory, a step-by-step workflow for Clostridioides difficile infection (CDI) detection using glutamate dehydrogenase (GDH) and toxin A/B assays for initial screening, along with a nucleic acid amplification test (NAAT), has been recommended recently. In this study, we evaluated these three immunoassays for the simultaneous detection of GDH and Clostridioides difficile (CD) toxin A/B. Methods: A total of 304 stool samples were tested for the presence of GDH antigen and CD toxin A/B using VIDAS C. difficile GDH and toxin A/B (CDAB), RIDASCREEN C. difficile GDH and toxin A/B (RIDA), and C. DIFF QUIK CHEK COMPLETE according to the manufacturers’ recommendations. As complementary reference methods for GDH and toxin A/B detection in the three immunoassays, CD cultures using ChromID C. difficile agar and the Xpert C. difficile assay, respectively, were tested. Results: All three GDH assays showed overall substantial agreement with the CD culture. All three toxin A/B assays showed overall moderate agreement with the Xpert C. difficile assay. In comparison with consensus results, VIDAS GDH and QCC GDH showed almost perfect agreement, whereas RIDA GDH showed inferior but substantial agreement. All three toxin A/B assays showed almost perfect agreement. Conclusions: Since the QCC GDH and toxin A/B assay is relatively more sensitive and specific than the other two immunoassays for discriminating toxigenic or non-toxigenic CDI, QCC is very helpful for the simultaneous identification of GDH and CD toxin A/B in the initial step of the two-round workflow for diagnosing CDI. Full article

The global escalation of severe infections due to carbapenemase-producing Enterobacterales (CPE) isolates has prompted increased usage of parenteral colistin. Considering the reported difficulties in assessing their susceptibility to colistin, the purpose of the study was to perform a comparative evaluation of six phenotypic assays—the colistin broth disc elution (CBDE), Vitek 2 Compact (bioMérieux SA, Marcy l’Etoile, France), the Micronaut MIC-Strip Colistin (Merlin Diagnostika GMBH, Bornheim-Hensel, Germany), the gradient diffusion strip Etest (bioMérieux SA, Marcy l’Etoile, France), ChromID Colistin R Agar (COLR) (bioMérieux SA, Marcy l’Etoile, France), and the Rapid Polymyxin NP Test (ELITechGroup, Signes, France)—versus the reference method of broth microdilution (BMD). All false resistance results were further assessed using population analysis profiling (PAP). Ninety-two nonrepetitive clinical CPE strains collected from two hospitals were evaluated. The BMD confirmed 36 (39.13%) isolates susceptible to colistin. According to the BMD, the Micronaut MIC-Strip Colistin, the CBDE, and the COLR medium exhibited category agreement (CA) of 100%. In comparison with the BMD, the highest very major discrepancy (VMD) was noted for Etest (n = 15), and the only false resistance results were recorded for the Rapid Polymyxin NP Test (n = 3). Only the PAP method and the Rapid Polymyxin NP Test were able to detect heteroresistant isolates (n = 2). Thus, there is an urgent need to further optimize the diagnosis strategies for colistin resistance. Full article

The aim of this study was to determine the prevalence of fecal ESBL-producing Escherichia coli (E. coli) in pigs on large and small farms in Latvia, to characterize beta-lactamase genes and establish an antimicrobial resistance profile. Fecal samples (n = 615) were collected from 4-week, 5-week, 6-week, 8-week, 12-week and 20-week-old piglets, pigs and sows on four large farms (L1, L2, L3, L4) and three small farms (S1, S2, S3) in Latvia. ChromArt ESBL agar and combination disc tests were used for the screening and confirmation of ESBL-producing E. coli. The antimicrobial resistance was determined by the disc diffusion method and ESBL genes were determined by polymerase chain reaction (PCR). Subsequently, ESBL-producing E. coli was confirmed on three large farms, L1 (64.3%), L2 (29.9%), L3 (10.7%) and one small farm, S1 (47.5%); n = 144 (23.4%). The prevalence of ESBL-producing E. coli differed considerably between the large and small farm groups (26.9% vs. 12.7%). Of ESBL E. coli isolates, 96% were multidrug-resistant (MDR), demonstrating there were more extensive MDR phenotypes on large farms. The distribution of ESBL genes was bla_TEM (94%), bla_CTX-M (86%) and bla_SHV (48%). On the small farm, bla_SHV dominated, thus demonstrating a positive association with resistance to amoxicillin-clavulanic acid, ceftazidime and cefixime, while on the large farms, bla_CTX-M with a positive association to cephalexin and several non-beta lactam antibiotics dominated. The results indicated the prevalence of a broad variety of ESBL-producing E. coli among the small and large farms, putting the larger farms at a higher risk. Individual monitoring of ESBL and their antimicrobial resistance could be an important step in revealing hazardous MDR ESBL-producing E. coli strains and reviewing the management of antibiotic use. Full article

Methicillin-resistant Staphylococcus aureus (MRSA) and non-aureus staphylococci (MRNAS) cause different infections in animals, including mastitis, in livestock and humans. This study aimed to identify and compare the staphylococcal chromosome cassette mec (SCCmec) types of MRSA or MRNAS isolated from several animal species and humans in different countries. Of 1462 S. aureus and non-aureus staphylococci, 68 grew on Chrom MRSA ID^® agar, were phenotypically resistant to cefoxitin and tested positive with the PCR for the mecA gene. These 60 MRSA and 8 MRNAS were isolated in Belgium mainly from cows (livestock-associated (LA) MRS) and humans (community-acquired (CA) MRS) and in Japan from dogs and cats. The SCCmec cassettes were identified by multiplex PCR in 52 MRSA and 7 MRNAS and by whole genome sequencing (WGS) in 8 additional MRSA. The SCCmec types IV and V were the most frequent in Belgian LA-MRS and CA-MRS, while the SCCmec type II was identified in four of the five Japanese MRSA. The remaining isolate was a bovine S. haemolyticus in which no SCCmec was identified. These results confirm the high prevalence of the SCCmec types IV and V in LA-MRS and CA-MRS in Belgium, emphasizing the possible public health hazard of the former, and the absence of SCCmec in some MRNAS. Full article

The isolation of non-O157 STEC from food samples has proved to be challenging. The selection of a suitable selective isolation agar remains problematic. The purpose of this study was to qualitatively and quantitatively evaluate six chromogenic agar media for the isolation of STEC: Tryptone Bile X-glucuronide agar (TBX), Rainbow^® Agar O157 (RB), Rapid E. coli O157:H7 (RE), Modified MacConkey Agar (mMac), CHROMagar^TM STEC (Chr ST) and chromID^TM EHEC (Chr ID). During this study, 45 E. coli strains were used, including 39 STEC strains belonging to 16 different O serogroups and 6 non-STEC E. coli. All E. coli strains were able to grow on TBX and RB, whereas one STEC strain was unable to grow on Chr ID and a number of other STEC strains did not grow on mMac, CHROMagar STEC and Rapid E. coli O157:H7. However, only the latter three agars were selective enough to completely inhibit the growth of the non-STEC E. coli. Our conclusion was that paired use of a more selective agar such as CHROMagar STEC together with a less selective agar like TBX or Chr ID might be the best solution for isolating non-O157 STEC from food. Full article