Medical students are exposed to the hospital environment and patients during their studies, increasing the risk of exposure to virulent and antibiotic-resistant isolates of Staphylococcus aureus. The aim of the study is to determine the prevalence of Staphylococcus aureus among medical students who have varying levels of exposure to the hospital environment to provide valuable insights into the risk of colonization and transmission. Nasal swabs and fingerprints were obtained and cultured on a selective medium for staphylococci. The obtained isolates were confirmed as methicillin-sensitive S. aureus (MSSA) or methicillin-resistant (MRSA) using PCR. Antibiotic resistance, the presence of virulence genes including enterotoxin encoding genes, and spa typing were performed. Among pre-clinical students, MSSA was detected on the nose in 45.2% and on the fingerprints in 10.6% of the participants. Among clinical students, MSSA was detected on the nose in 42.0% and on the fingerprints in 25.4%. Only one MRSA isolate was obtained. Genes seg and sei were the most frequently detected in both student groups, with their presence in over 40% of isolates among clinical students. The eta and etb genes were mainly detected from the nose in both student groups. In pre-clinical students, S. aureus carrying eta gene occurred in 6.4% and etb in 8.5%. In clinical students, the occurrence was 5.1% for eta and 8.5% for etb. The tst gene was identified only in the nose and fingerprints of the clinical student group. The most frequently observed resistance was to clindamycin and erythromycin. In total 58 different spa types were identified. High rates of asymptomatic MSSA carriage were observed in both groups of medical students. Detected MSSA strains showed a high degree of genetic variability, with a number of them carrying the virulence and antibiotic resistance genes. Although students do not exhibit increased risk to their patient's, increased hygiene is required in asymptomatic carriage personnel. The overall prevalence of MRSA was low, with a minimal risk of spread.

• Keywords
• Spa type, Staphylococcus aureus, Antibiotic resistance, MRSA, Medical students, Virulence genes,
• MeSH
• Anti-Bacterial Agents pharmacology   MeSH
• Asymptomatic Infections epidemiology   MeSH
• Drug Resistance, Bacterial MeSH
• Adult MeSH
• Virulence Factors genetics   MeSH
• Humans MeSH
• Methicillin-Resistant Staphylococcus aureus genetics   isolation & purification   MeSH
• Microbial Sensitivity Tests MeSH
• Young Adult MeSH
• Nose microbiology   MeSH
• Carrier State * microbiology   epidemiology   MeSH
• Prevalence MeSH
• Staphylococcal Infections * microbiology   epidemiology   MeSH
• Staphylococcus aureus * genetics   isolation & purification   drug effects   classification   MeSH
• Students, Medical * MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Young Adult MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• Virulence Factors MeSH

OBJECTIVES: We performed a retrospective analysis of MRSA isolates collected at the university equine clinic including clinical isolates from 2008 to 2021 and screening environmental, equine and personnel isolates from 2016. METHODS: Screening and clinical samples were cultured on Brilliance MRSA 2 and Columbia agar (Oxoid), respectively, with enrichment for environmental samples. Antimicrobial susceptibility was assessed by disc diffusion. All the isolates were characterized by spa typing. Eighteen selected isolates were subjected to WGS with subsequent wgMLST clonal analysis. RESULTS: Among 75 MRSA isolates, five spa types were identified, the majority (n = 67; 89.33%) was t011. All isolates were resistant to cefoxitin and ampicillin and carried the mecA gene. In addition, the isolates were resistant to tetracycline (n = 74; 98.67%), gentamicin (n = 70; 93.33%), enrofloxacin (n = 54; 72.00%), sulfamethoxazole-trimethoprim (n = 5; 6.67%) and lincomycin (n = 3; 4.00%) with corresponding genetic markers for the resistance detected in the sequenced isolates. All 18 sequenced isolates belonged to ST398, 16 carried SCCmec type IVa and two carried SCCmec type Vc (5C2&5). Further, isolates carried aur, hlgA, hlgB and hlgC virulence genes, and five isolates carried sak and scn genes, which are part of the immune evasion cluster. Close genetic relatedness was found between isolates from the staff of the clinic and clinical samples of horses. CONCLUSIONS: Repeated introduction and long-term persistence of the equine LA-MRSA subclone (ST398-MRSA-IVa/Vc(5C2&5), t011) among the infected horses at the equine clinic with the colonization of personnel, and the environment contamination that might contribute to transmission were observed.

• MeSH
• Anti-Bacterial Agents * pharmacology   MeSH
• Bacterial Proteins genetics   MeSH
• Horses microbiology   MeSH
• Humans MeSH
• Methicillin-Resistant Staphylococcus aureus * genetics   isolation & purification   drug effects   classification   MeSH
• Microbial Sensitivity Tests * MeSH
• Environmental Microbiology MeSH
• Drug Resistance, Multiple, Bacterial genetics   MeSH
• Multilocus Sequence Typing MeSH
• Horse Diseases microbiology   MeSH
• Hospitals, Animal MeSH
• Retrospective Studies MeSH
• Whole Genome Sequencing MeSH
• Staphylococcal Infections * microbiology   veterinary   epidemiology   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anti-Bacterial Agents * MeSH
• Bacterial Proteins MeSH