Characterization of Extended Spectrum B-Lactamase Producing Enterobacteria and Methicillin-Resistant Staphylococcus aureus Isolated from Raw Pork and Cooked Pork Products in South China

In this study, we assessed the co-colonization with extended spectrum -lactamase producing Enterobacteria (ESBL-E) and methicillin-resistant Staphylococcus aureus (MRSA) in raw pork and cooked pork products in south China. In total, 240 raw pork and 240 cooked pork samples collected from supermarkets (n = 20) and local butcher shops (n = 20) in the city of Guangzhou (China) were investigated. Raw pork and cooked pork was more frequent colonization with ESBL-E (7.5% in raw pork and 0.4% in cooked pork products) than with MRSA (4.2% in raw pork). Two of samples were contaminated with both tested types of multidrug-resistant bacteria. High antibiotic-resistance rate with wide spectrums of both ESBL-E and MRSA isolated were observed. In ESBL-E isolates, TEM (n = 15), CTX-M-1 (n = 3), CTX-M-9 (n = 1), and SHV (n = 1) genes were detected. TEM and SHV genes were associated with CTX-M-1 in 2 isolates, respectively. The CTX-M-9 gene of 1 isolate from cooked pork samples was found to be transferred to Escherichia coli J53 by conjugation. Detected MLST-types of MRSA were livestock-associated ST7 (n = 5) and ST9 (n = 4), as well as hospital-acquired ST239 (n = 1), suggesting contamination from human source(s) during meat processing. These findings confirmed a contamination of raw pork and cooked pork with ESBL-E and MRSA and emphasized the necessity of enforcing hygienic practices and specific detection of MRSA and ESBL-producing bacteria in meat processing and storage. Practical Application Our findings confirmed the present of methicillin-resistant Staphylococcus aureus (MRSA) and extended spectrum -lactamase producing Enterobacteria (ESBL-E) in raw pork and cooked pork products. The presence of diverse ESBL-encoding genes and the extended host spectrum genotypes ST239 in MRSA from pork suggest retail pork products could serve as a reservoir for multidrug-resistant bacteria which may potentially transfer to humans through the food chain. This study emphasized the necessity of enforcing hygienic practices and specific detection of MRSA and ESBL-producing bacteria in meat processing and storage.