Genomic analyses reveal presence of extensively drug-resistant serovars isolated from clinical samples in Guizhou province, China, 2019-2023.

BACKGROUND

The emergence of extensively drug-resistant (XDR) in humans poses a significant public health and therapeutic challenge. However, limited data are available on XDR isolates from Guizhou province, China. This study aimed to investigate the molecular epidemiology and resistance patterns of XDR isolates from clinical samples in this region.

METHODS

A total of 931 isolates were screened for XDR isolates through antimicrobial susceptibility testing. These XDR isolates were subjected to whole-genome sequencing (WGS) and bioinformatic analysis to further systematically investigating the molecular epidemiology and resistance patterns of XDR isolates.

RESULTS

Between 2019 and 2023, 931 isolates were collected from clinical samples in Guizhou. Of these isolates, 51 (5.5%) were identified as XDR and classified into 16 serovars. Among the serovars, 15 corresponded to a specific sequence type, except for serovars. The predominant serovars, . 1,4,[5],12:i:-, , and . Kentucky, were divided into ST34, ST11, and ST198, respectively. Genomic analysis showed that all XDR isolates harbored at least eight antimicrobial resistance genes (ARGs) and multidrug efflux pumps. Highly prevalent point mutations in (D87 and S83) and (S80I) were detected, along with eight plasmid-mediated quinolone resistance () genes. The gene was the most common (43.1%), followed by , variant, , , , , and . The predominant -lactamase gene was (54.9%), and (35.3%) was the most prevalent extended-spectrum -lactamase subtype. Notably, gene was identified for the first time in from Guizhou, and one 1,4,[5],12:i:- isolate contained the gene. ARGs profiles varied by serovars, with 1,4,[5],12:i:- isolates carrying the highest number. Ten plasmid types were identified, predominantly IncHI2/IncHI2A (47.5%). Key resistance genes such as , , , , and were located on IncHI2/IncHI2A plasmids. Notably, 75.0% of the conjugative plasmids belonged to IncHI2/IncHI2A, indicating that horizontal gene transfer through conjugation facilitates ARGs dissemination. Core genome multilocus sequence typing (cgMLST) analysis revealed significant genetic diversity, with 39 core genome sequence types (cgSTs) identified and no evidence of outbreaks.

CONCLUSION

The rising prevalence of XDR in Guizhou province is concerning. Initial whole-genome sequencing (WGS) data provide critical insights for understanding and controlling XDR infections, aiding public health officials in identifying emerging threats and trends.