Epidemiology and genetic characterization of (X4)-positive and isolated from raw meat in Chengdu City, China.

The rapid spread of mobile tigecycline resistance presents a significant public health threat, particularly with the increasing prevalence of (X4)-positive Enterobacterales across various species. This study aimed to investigate the epidemic features and transmission dynamics of (X4)-positive (. ) through the analysis of 206 raw meats, including pork ( = 182), beef ( = 16), duck ( = 5), and chicken ( = 3). These samples were collected from schools, markets, and restaurants in Chengdu City, China. A total of 25 isolates were obtained from 13 administrative regions. All isolates exhibited resistance to tetracycline, tigecycline, ampicillin, chloramphenicol, and florfenicol. Over half of the isolates also demonstrated resistance to streptomycin (80 %), sulfamethoxazole/trimethoprim (72 %), ciprofloxacin (64 %), and ampicillin/sulbactam (56 %). Among these strains, 14 distinct sequence types (STs) were identified, revealing evidence of inter-regional clonal spread, notably among 9  ST3393. Phylogenetic analysis revealed the presence of two ST5 closely resembling hypervirulent from Jiangsu. Importantly, 12 isolates were capable of transferring tigecycline resistance to J53. Further plasmid analysis showed that the (X4)-harboring plasmids in could be classified into four types, primarily belonging to the IncFIA(HI1)/HI1A/HI1B hybrid plasmid ( = 16) and IncFII plasmid ( = 7), which significantly contributed to the cross-species dissemination of (X4). In summary, this study highlights the prevalence of MDR (X4)-positive in Chengdu, driven predominantly by clonal expansion and plasmid-mediated horizontal gene transfer. These findings emphasize the importance of continuous surveillance of (X4)-positive in raw meat and the implementation of effective measures to control their spread.