Prevalence, Characterization, and Antimicrobial Susceptibility of from Raw Beef and Slaughterhouse Environments in Korea.

The prevalence of in raw beef and in slaughterhouse environments was investigated from April 2019 to February 2020. Three hundred raw beef samples were purchased from 50 retailers and 10 restaurants (5 samples per source). One hundred and thirty-four samples from slaughterhouse environments were collected by swabbing (10 × 10 cm) the surfaces, gloves, splitting saw, and drains. was detected and identified according to the method described in ISO 11290-1, and confirmed by 16S rRNA sequencing. was detected in raw beef (2/300, 0.7%), gloves used in carcass splitting (6/21, 28.6%), the splitting saw (1/18, 5.6%), and the drain zone (1/15, 6.7%). All isolates were serotype 1/2a or 1/2c, based on screening using multiplex PCR-based serogrouping assay and serotyping kit for O-H antigens. Pulsed-field gel electrophoresis (PFGE) following I digestion of eight PFGE pulsotypes and four PFGE groups were identified. Biofilm formation analysis using Crystal Violet staining revealed the highest biofilm formation in strain LM-16, followed by D190613. Although isolates were susceptible to most antimicrobials, some resistance to penicillin (8/15, 53.3%) and tetracycline (2/15, 13.3%) was observed. Through PFGE, G190426, G190829, and G200210 isolated from the same location in this study were genetically homologous similar to the LM-16 strain, previously isolated from beef carcass in 2006. These results suggest that LM-16 has been continuously present in biofilms in the slaughterhouse environments since 2006. Our study indicates that contamination in raw beef could consistently occur during beef processing in slaughterhouse environments through contact with gloves, splitting saws, and drains.