Streptococcus uberis is one of the primary causative agents of mastitis, a clinically and economically significant disease that affects dairy cattle worldwide. In this study, we analyzed 140 S. uberis strains isolated from mastitis milk samples collected from 74 cow herds in the Czech Republic. We employed whole-genome sequencing to screen for the presence of antimicrobial resistance (AMR) genes and genes encoding virulence factors, and to assess their genetic relationships. Our analysis revealed the presence of 88 different sequence types (STs), with 41% of the isolates assigned to global clonal complexes (GCCs), the majority of which were affiliated with GCC5. The STs identified were distributed across the major phylogenetic branches of all currently known STs. We identified fifty-one putative virulence factor genes, and the majority of isolates carried between 27 and 29 of these genes. A tendency of virulence factors and AMR genes to cluster with specific STs was observed, although such clustering was not evident within GCCs. Principal component analysis did not reveal significant diversity among isolates when grouped by GCC or ST prevalence. The substantial genomic diversity and the wide array of virulence factors found in S. uberis strains present a challenge for the implementation of effective anti-mastitis measures.

• Klíčová slova
• MLST, antimicrobial resistance genes, intramammary infection, mastitis, phylogenetic tree, sequence type, virulence genes,
• Publikační typ
• časopisecké články MeSH

Streptococcus uberis is one of the most important causative agents of mastitis and is a common reason for the use of antimicrobials in dairy cows. In this study, we assessed the antimicrobial susceptibility of 667 S. uberis isolates originating from 216 Czech dairy farms collected between 2019 and 2023 using the broth microdilution method. We tested 140 of the isolates for the presence of antimicrobial genes using whole-genome sequencing and evaluated their relationship with phenotypic resistance. Streptococcus uberis isolates showed high levels of resistance to tetracycline (59%), followed by streptomycin (38%) and clindamycin (29%). Although all of the isolates were susceptible to beta-lactams, a relatively high percentage of intermediately susceptible isolates was recorded for ampicillin (44%) and penicillin (18%). The isolates were mainly resistant to tetracycline alone (31.3%); the second most frequent occurrence of the phenotypic profile was simultaneous resistance to tetracycline, streptomycin, and clindamycin (16.6%). The occurrence of antibiotic resistance genes did not always match the phenotypic results; in total, 36.8% of isolates that possessed the ant(6)-Ia gene did not show phenotypic resistance to streptomycin. To a lesser extent, silent genes were also detected in clindamycin and tetracycline. This study confirmed the high susceptibility of S. uberis to penicillins used as first-line antimicrobials for S. uberis mastitis treatment.

• Klíčová slova
• Streptococcus uberis, antimicrobial resistance gene, antimicrobial resistence, bovine mastitis, intramammary infection, whole-genome sequencing,
• Publikační typ
• časopisecké články MeSH

Klebsiella pneumoniae is a major zoonotic pathogen that causes a variety of severe illnesses as well as mastitis. The distribution of mastitis-causing K. Pneumoniae and its virulence factors vary by country and geographical location. The present study aimed to find out the occurrence of Multidrug-resistant (MDR) K. Pneumoniae and their capsular resistance genes which were undocumented previously in cow farms of district Peshawar, Pakistan. A total of 700 milk samples from symptomatic mastitic cows were screened for MDR K. Pneumoniae. Furthermore, the characterization of capsular resistance genes was done by molecular techniques. Among these samples, K. pneumoniae was found 180/700 (25.7%), while MDR K. pneumoniae was found 80/180 (44.4%). The antibiogram analysis revealed high resistance to Vancomycin (95%) while highly sensitive to Ceftazidime (80%). The distribution of capsular genes shows the most common serotype K2 gene 39/80 (48.7%), followed by serotype K1 gene 34/80 (42.5%), serotype K5 17/80 (21.2%), and serotype K54 13/80 (16.2), respectively. Moreover, the co-occurrence of serotypes K1+K2 was found at 11.25%, KI+K5 was 05%, K1+K54 was 3.75%, and K2+K5 was 7.5%, respectively. A statistically significant association (p ≤ 0.05) was found between predicted and discovered K. pneumoniae values. In conclusion, the presence of MDR K. pneumoniae in combination with capsular genes may be a possible threat to dairy farm animals and humans in Peshawar, Pakistan. It may give us special attention to follow up on hygienic practices in livestock management.

• MeSH
• farmy MeSH
• hospodářská zvířata MeSH
• Klebsiella pneumoniae * genetika   MeSH
• lidé MeSH
• mastitida * MeSH
• skot MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• skot MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Pákistán epidemiologie   MeSH

The ubiquitous occurrence and high heterogeneity of Streptococcus uberis strains cause difficulties in the development and implementation of effective control strategies in dairy herds. In this study, S. uberis strains from 74 farms, obtained predominantly from subclinical, acute, and chronic recurrent mastitis, as well as from udder surface swabs and milk from healthy udders, were analysed for their genetic diversity using multilocus sequence typing (MLST). Isolates were tested for the presence of the genes encoding the virulence factors using polymerase chain reaction. Antibiotic susceptibility testing was performed using a microdilution assay including 14 antimicrobials. The virulence profiles and antimicrobial (AMR) profiles of the isolates were assembled and the overall heterogeneity was evaluated. Among the 124 isolates, 89 MLST genotypes, 7 different virulence profiles, and 12 AMR profiles were identified. The large number of different MLST allelic profiles in this study points to the high heterogeneity of strains in dairy herds in the Czech Republic. Isolates of a certain MLST genotype may possess a different set of virulence factor genes. We detected up to three different resistance profiles within a single MLST genotype. The results of our study showed that fully susceptible isolates coexisted with resistant or even multiresistant isolates in the same herd. Multiple genotypes within a herd were detected on many farms (up to seven MLST genotypes and four AMR profiles in one herd). This heterogenic population structure might suggest that environmental transmission is the predominant route of infection in herds in the Czech Republic.

• Klíčová slova
• MLST, antimicrobial resistance, cows, intramammary infection, virulence factors,
• Publikační typ
• časopisecké články MeSH