Analysis of contamination with drug-resistant bacteria among three types of commercially available pork in Beijing and Shanxi,China

Abstract

The contamination of pork with drug-resistant bacteria seriously affects food safety and human health. This study analyzed the characteristics of contaminating drug-resistant bacteria among three types of commercially available pork (i.e., intensively farmed, organic and free-range). The results revealed that seven antibiotic-resistant strains were present in all three pork samples, and the total number of bacterial colonies of antibiotic-resistant strains in the intensively farmed pork samples was significantly different from those in the organic and free-range pork (P < 0.05), while there was no difference between the organic and free-range pork. The multidrug resistance(MDR) rates were 91.88%, 85.27% and 73.11% for the bacterial isolates from these kinds of pork，which significantly differed between the three types of pork samples (P < 0.05). Nine resistance genes were detected, among which sul1 and aac(6′)-Ib-cr had the highest detection rates of 85.26% and 79.47%, respectively. Class I integron genes were detected in MDR strains from all three types of pork, but only four β-lactam gene cassettes were detected in the intensively farmed strains. In summary, all three types of pork were contaminated with resistant bacteria, but there were differences in the MDR rates and the presence of drug-resistant genes.