Occurrence of Methicillin-Resistant Staphylococcus aureus in Ready-to-Eat Raw Fish from Japanese Cuisine Restaurants in Salvador, Brazil

Abstract

The presence of methicillin-resistant Staphylococcus aureus (MRSA) strains in food products is a major issue for food safety. The present study was conducted to evaluate the occurrence and antimicrobial resistance profile of S. aureus, focusing on MRSA isolates, in ready-to-eat sashimi from Japanese restaurants in Salvador, Brazil. A total of 127 sashimi samples were collected directly from the take-out service in 16 restaurants. The staphylococcal isolates were identified morphologically and biochemically with standard laboratory procedures. S. aureus isolates were tested with a disk diffusion assay against seven antibiotics, and the cefoxitin and oxacillin were used to identify MRSA strains. Isolates with the MRSA phenotype were confirmed with a PCR assay. S. aureus was found in 73% of the sashimi samples, including sashimi from tuna (75.5% of samples) and salmon (72.5% of samples). Among those positive samples, 37% were contaminated with MRSA strains, found among 38.8% of salmon sashimi and 34.0% of tuna sashimi. Penicillin resistance was the most common type of antimicrobial resistance, found in 65.5% of the sashimi samples, followed by resistance to tetracycline (22.5%), erythromycin (16.0%), and ciprofloxacin (3.2%). Only two S. aureus isolates collected from different fish samples and restaurants had presumed resistance to vancomycin. The high prevalence of S. aureus and MRSA in these sashimi samples indicates a potential risk for foodborne disease, especially MRSA, spreading in the community.