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Abstract: A total of 47 Listeria monocytogenes isolates were separated and identified from 153 retailed raw meat samples in Shanghai area with the highest contamination rate in pork meat (20.34%). Using multiplex PCR, these isolates were divided into 3 serogroups: 1/2a‐3a, 1/2b‐3b‐7, and 1/2c‐3c, and 1/2a‐3a was predominant in these isolates. Calgary device was introduced to cultivate biofilm, and crystal violet staining and viable cell enumeration was used to determine the quantity of biofilm formation. Meat juices significantly impacted the biofilm formation, and L. monocytogenes had the highest biofilm‐forming ability in pork juice. However, there was no significant difference on biofilm formation among different serotypes and sources. When cocultured in pork juice, the cell numbers of Salmonella enterica, Staphylococcus aureus, and L. monocytogenes had a significant decrease or decreasing tendency compared to monospecies biofilm, which revealed a competitive interaction among the three species. Practical applications: It is aimed to investigate the biofilm formation by L. monocytogenes on plastic surface in different meat juices (beef, chicken, and pork) and the interaction among the multispecies biofilm of Salmonella, Staphylococcus aureus, and L. monocytogenes in pork juice. Meat juice was used as a simulation of the real condition in meat processing environment, and the result can give suggestions to meat industry to keep a close eye on raw pork product. [ABSTRACT FROM AUTHOR]

Biofilm formation usually increases antimicrobial resistance capacity of Staphylococcus aureus, which poses considerable challenges to successful eradication of staphylococcal infections. Very little is known about the biofilm-forming capacity and antibiotic resistance pattern of dominant S. aureus clonal lineages in China. In this study, the disk diffusion method and the microtiter plate assay were, respectively, performed to determine the antibiotic resistance and biofilm-forming capacity of 84 different S. aureus isolates belonging to 10 dominant clonal lineages in China. It was shown that isolates of different clonal lineages had obvious variations in biofilm-forming capacity. Resistance to individual antibacterial agents was most frequently observed to erythromycin (72.6%) and azithromycin (72.6%). Then, all tested isolates were further screened for the presence of 16 resistance genes by polymerase chain reaction (PCR), and no significant correlation was found between clonal lineage and the distribution of resistance genes. Overall, our results indicate that biofilm producers of S. aureus have a greater likelihood to carry more antibiotic resistance genes than non-biofilm producers ( p < .01), further implying that biofilm may promote the dissemination of antibiotic resistance determinants. Practical applications Staphylococcus aureus is the leading cause of nosocomial infections and often associated with food poisoning worldwide. Biofilm formation of S. aureus influences the efficacy of antimicrobial therapy and promotes the persistence of infections; however, the knowledge about biofilm formation capacity of isolates belonging to different clonal lineages is little. Therefore, this study on biofilm formation capacity and antibiotic resistance pattern of dominant S. aureus clonal lineages could help to fix this information gap. [ABSTRACT FROM AUTHOR]