Isolation of methicillin-resistant Staphylococcus aureus in a dental clinic environment

Objective: to quantify Staphylococcus aureus strains isolates collected in a dental clinical environment and to determine their susceptibility to some of the most common antimicrobial agents used in dentistry. Methods: Sterile cotton swabs were used to collect the samples from dental-chair push buttons, light handles, 3-in-1 syringes, computer "Enter" keys, doorknobs, and X-ray tubes before, during, and after clinical procedures. These samples were spread on Salt Manitol Agar and were incubated at 37 degrees C for 24 hours. The resulting S. aureus isolates were counted and classified using Gram staining and biochemical tests. The counts among the 3 periods and the groups were analyzed by Kruskal-Wallis and Dunn tests (alpha =5%). The antimicrobial resistance of the isolated microorganisms was evaluated by using commercial paper discs impregnated with the following antibiotics: ampicillin; amoxicillin; amoxicillin/clavulanic acid; azithromycin; cefadroxil; clarithromycin; clindamicin; erythromycin; penicillin G; methicillin, oxacillin and vancomycin.. Results: An increase in the number of Staphylococcus aureus was observed during clinical procedures (p<0.05). The dental-chair push buttons were the most contaminated (p<0.05). The highest bacterial resistance rates were observed for the beta -lactam group (91%). All isolated strains were sensitive to vancomycin, and 5% of them were resistant to methicillin. Conclusions: Clinical procedures increased the number of antimicrobial-resistant S. aureus isolates dispersed in a dental clinical environment, including methicillin-resistant Staphylococcus aureus strains.