Hands as a Potential Vector for Transmission of Multidrug-Resistant Staphylococcus aureus Polyclonal Strains in Dental Clinical Environments

Abstract

Background: Staphylococcus aureus has been considered one of the main opportunistic pathogens for humans, constituting a relevant problem, considering its possible resistance to the main antibiotics used in medical practice. The aim of this study was to detect the presence of oxacillin-resistant S. aureus (ORSA) in the hands of undergraduate dentistry students, throughout clinical procedures (before and after dental procedures and hand hygiene). Methods: Hand samples were collected at different times (preasepsis; immediately after asepsis; and glove and hand surfaces immediately after dental procedures) and seeded in culture media (PCA and MSA). S. aureus species were characterized by microbiological identification methods, antimicrobial susceptibility test and genotyping by isoenzymatic markers. Results: A total of 14 students (73.7%) had S. aureus in both hands. Microbial resistance was observed in 87.1% of S. aureus isolates: AMP (54.5%), AMX (26.5%), OXA (12.9%), TET (7.6%), CFE (7.6%), LEX (7.6%), FOX (7.6%), CLI (15.2%) and ERY (44.7%). A total of 132 isolates of S. aureus with variable profiles of antimicrobial resistance were identified, 26 of which were characterized as ORSA. Monoclonal and polyclonal patterns were observed in bacteria population. Analyzes of genetic relationship revealed that two or more dentistry students share S. aureus isolates through their hands and gloves during their academic clinical activities. Conclusion: The spread of multidrug-resistant S. aureus mono and polyclonal strains requires a reevaluation of personal hygiene and environment (effective biosafety practices) as a means of preventing the spread and cross-contamination between patients, professionals and academics, and dental clinical environments.