A recent study conducted by Chinese researchers has underscored the growing concern over the presence of multidrug-resistant (MDR) and methicillin-resistant Staphylococcus aureus (MRSA) in packaged food, shedding light on potential health risks associated with ready-to-eat (RTE) food products.
Published in the journal Zoonoses, the study, carried out by experts from the China National Center for Food Safety Risk Assessment, delved into the analysis of 276 S. aureus isolates linked to RTE foods. These isolates were collected from various retail outlets, including supermarkets, convenience stores, fast food restaurants, and farm-product markets across 25 different provinces in China during the year 2018. Researchers conducted comprehensive assessments, examining factors such as antimicrobial susceptibility, virulence traits, and molecular characteristics.
Previous research in 2015 by Chinese scientists had identified a 4.3% contamination rate of retail foods with S. aureus, known to be capable of causing staphylococcal food poisoning (SFP). However, this recent study aimed to address the prevalence and epidemiological features of MRSA in RTE food, which had remained uncharted territory.
The findings of the study were concerning, with 250 out of the 276 isolates (90.6%) demonstrating resistance to at least one antimicrobial agent. Alarmingly, 73 of these isolates (26.4%) exhibited multidrug resistance, signifying resistance to three or more antimicrobial drugs. Within this MDR category, the study identified 30 MRSA isolates, and researchers detected nine distinct toxin genes. Most notably, 60% of the MRSA isolates carried multiple toxin genes. Researchers identified a total of thirteen sequence types, with the most prevalent MRSA lineages being CC59-t437-SCCmecIV/V (23.3%), CC398-t011-SCCmecV (23.3%), and CC1-t114-SCCmecIV (16.7%).
The study also revealed that the genetic diversity of MRSA isolates correlated with their antimicrobial resistance profiles and virulence gene content.
In light of these findings, the researchers emphasized the importance of monitoring MRSA genotypes in RTE foods, as it could aid in tracking the origin of contamination, assessing antimicrobial resistance levels, and evaluating the risk associated with SFP. They concluded, “Such efforts will play a pivotal role in assisting government authorities, the food industry, and relevant stakeholders in enhancing food safety measures and controlling the transmission pathways of this bacterium.”