A Comprehensive Study on Antibiotic Resistance among Coagulase-Negative Staphylococci (CoNS) Strains Isolated from Ready-to-Eat Food Served in Bars and Restaurants

The present study aimed to characterize and assess the diversity of CoNS strains as potential vectors for the spread of resistance to antimicrobial agents from RTE foods served in bars and restaurants. Eighty-five CoNS strains, obtained from 198 RTE food samples, were investigated. Sixty-seven CoNS isolates (78.8%) were resistant to at least one antibiotic tested, and 37 (43.5%) were multidrug resistant (MDR-CoNS). Moreover, CoNS strains contained genes conferring resistance to antibiotics critically important in medicine, i.e., beta-lactams [mecA (29.4%); blaZ (84.7%)], aminoglycosides [aac(6 ')-Ie-aph(2 '')-Ia (45.9%); aph(2 '')-Ic (3.5%)], macrolides, lincosamides and streptogramin B-MLSB [msrA/B (68.2%); ermB (40%) and mphC (4.7%)], tetracyclines [tetK (31.8%); tetM (16.5%) and/or tetL (2.35%)]. We also found the fusB/C/D genes responsible for the acquired low-level fusidic acid resistance (17.6%) and streptogramin resistance determinant vgaA in 30.6% of isolates. In three linezolid resistant strains (2 S. epidermidis and 1 S. warneri), mutation was detected, as demonstrated by L101V and V188I changes in the L3 protein amino acid sequences. The high frequency in RTE food of MDR-CoNS including methicillin-resistant (MR-CoNS) strains constitutes a direct risk to public health as they increase the gene pool from which pathogenic bacteria can pick up resistance traits.

Automated summary

The present study aimed to evaluate and describe the diversity of CoNS strains as potential vectors for the transmission of antimicrobial resistance from RTE foods served in bars and restaurants. The study found that out of 85 CoNS strains, 67 strains were resistant to at least one antibiotic, with 37 strains exhibiting multidrug resistance (MDR-CoNS). Furthermore, CoNS strains carried resistance genes for antibiotics critically important in medicine, such as beta-lactams, aminoglycosides, and tetracyclines. The high frequency of MDR-CoNS in RTE foods poses a direct risk to public health as it contributes to the gene pool for acquisition of resistance traits by pathogenic bacteria.