Comparative Analysis of Antibiotic Resistance and Biofilm Characteristics of Two Major IEnterococcus/I Species from Poultry Slaughterhouses in South Korea

This study focused on the antibiotic resistance and biofilm characteristics of two predominant species of Enterococcus, E. faecalis and E. faecium, isolated in poultry slaughterhouses in South Korea. E. faecium showed a broader range of antibiotic resistance, particularly to linezolid and rifampicin. A high level of multidrug resistance was also observed in E. faecalis (95.8%) and E. faecium (93.8%). E. faecalis formed more robust biofilms than E. faecium. We also identified several specific genes (cob, ccf, and sprE) that were associated with the strength of the biofilm. There was no general correlation between antibiotic resistance and biofilm strength found in the isolates used in this study. These findings point to the potential health risks of these drug-resistant bacteria as they can spread from poultry to humans through the food supply chain. The spread of antibiotic-resistant Enterococcus in the poultry industry poses significant public health challenges due to multidrug resistance and biofilm formation. We investigated the antibiotic resistance profiles and biofilm characteristics of E. faecalis and E. faecium isolates from chicken meat in poultry slaughterhouses in South Korea. Ninety-six isolates (forty-eight each of E. faecalis and E. faecium) were collected between March and September 2022. Both species were analyzed using MALDI-TOF, PCR, antibiotic susceptibility testing, and biofilm assays. A high level of multidrug resistance was observed in E. faecalis (95.8%) and E. faecium (93.8%), with E. faecium exhibiting a broader range of resistance, particularly to linezolid (52.1%) and rifampicin (47.9%). All E. faecalis isolates formed biofilm in vitro, showing stronger biofilm formation than E. faecium with a significant difference (p < 0.001) in biofilm strength. Specific genes (cob, ccf, and sprE) were found to be correlated with biofilm strength. In E. faecium isolates, biofilm strength was correlated with resistance to linezolid and rifampicin, while a general correlation between antibiotic resistance and biofilm strength was not established. Through analysis, correlations were noted between antibiotics within the same class, while no general trends were evident in other analyzed factors. This study highlights the public health risks posed by multidrug-resistant enterococci collected from poultry slaughterhouses, emphasizing the complexity of the biofilm-resistance relationship and the need for enhanced control measures.