Antimicrobial Resistance, Multilocus Sequence, and spa Typing of Staphylococcus aureus Isolated from Retail Raw Meat Products

Abstract

With a high capacity to acquire antimicrobial resistance, Staphylococcus aureus is an important pathogen causing severe infections in animals and humans. A total of 50 Staphylococcus aureus isolates from retail ground beef, chicken meat, and fish were characterized by antimicrobial resistance profiling, staphylococcal protein A gene (spa) typing, and multilocus sequence typing (MLST). The broth microdilution test results showed that all isolates were resistant to penicillin and sulphamethoxazole but had varying resistance rates to tetracycline (24%), erythromycin (4%), gentamicin (2%), ciprofloxacin (2%), trimethoprim (2%), and chloramphenicol (0%). The blaZ and sulI genes were detected in 100% of the isolates followed by grlA (94%), norA (92%), tetK (80%), chlA (60%), tetM (26%), aacA-aphD (2%), ermA (2%), fexA (0%), and dfrA (0%). Moreover, 26% of the isolates were multidrug-resistant, with five or more resistance genes. The spa typing analysis revealed 22 spa types, with t091 (16%), t1677 (8%), and t14538 (8%) being the most common, and one new spa type, t19851, was uncovered. MLST identified seven sequence types (STs), with ST7 (40%), ST15 (20%), and ST199 (13%) being the most common, and two STs (ST7435 and ST7436) were newly identified. In this study, S. aureus isolated from raw meat showed multidrug resistance and different clones associated with human infections. As a result, foods of animal origin may act as potential vehicles for transmission of multidrug-resistant S. aureus isolates, and the dissemination of potentially pathogenic clonal types, posing a health risk to humans.