Abstract
Background: Staphylococcus aureus (S. aureus) is an opportunistic pathogen widely present in humans and food-producing animals. The emergence of antimicrobial resistance (AMR) in S. aureus represents a major challenge for both animal and public health.
Aim: The aim of the present study is to assess the contamination and AMR of S. aureus isolates from 48 retail pork samples collected from traditional markets in Central Vietnam.
Methods: Forty-eight retail pork samples were collected from traditional markets in Central Vietnam. The S. aureus count (log10 CFU/g) was determined using Baird-Parker (BP) medium and confirmed by the coagulase reaction. The S. aureus isolates were tested for AMR and antimicrobial resistance genes (ARGs) using the disk diffusion method and PCR, respectively.
Results: The results showed that all 48 pork samples (100%) tested positive for S. aureus, with S. aureus counts ranged from 4.17 to 4.52 log10 CFU/g. The AMR was most commonly observed against penicillin (75.0%), followed by amoxicillin (64.6%), tetracycline (54.2%), ampicillin (41.7%), neomycin (39.6%), and vancomycin (39.6%). Multidrug resistance (MDR) was observed in 85.4% of the S. aureus isolates, with penicillin-ampicillin-amoxicillin being the most common resistance pattern. The highest frequency of S. aureus isolates carryed the tetM (30/48, 62.5%) gene, followed by blaZ (25/48, 52.1%), and femA (20/48, 41.7%). Moreover, the results revealed the positive correlation among β-lactams, specifically between ampicillin and neomycin, as well as between amoxicillin and erythromycin/neomycin.
Conclusion: The high AMR in S. aureus isolates from retail pork is alarming and raises public health concerns. Food of animal origin serves as a source of AMR S. aureus, which can spread through the food supply chain. Therefore, controlling S. aureus requires targeting specific entry points based on findings related to risk factors and drivers of food contamination.

Key words: S. aureus, retail, antimicrobial resistance, Vietnam, market