[Genetic diversity analysis of oxacillinase in 241 clinical isolates of ].

To analyze the carriage status, subtype distribution and flanking gene sequence characteristics of oxacillinases (OXA enzyme) in 241 clinical strains of Pseudomonas aeruginosa, and assess their roles in the drug resistance of and ability to horizontally transfer across species. Clinical isolates were collected from four hospitals in Sanya, Tangshan, Zhangjiakou, and Beijing. The prevalence of oxacillinases and their flanking gene sequences was analyzed by whole-genome sequencing (NGS) and bioinformatic approaches. A total of 241 isolates of were gathered, and 35 subtypes were identified through screening of 252 genes. These genes were classified into three subfamilies: (241, 95.6%), (9, 3.6%) and (2, 0.8%). Among these, 11 subtypes (11, 31.4%) were novel subtypes. Nine of these belonged to the subfamily and were designated as , , , , , , , , and . The remaining two belonged to the subfamily and were named and . Compared to the amino acid sequence of OXA-10, the newly identified subtype OXA-1247 exhibited a mutation at position 117, where a valine was replaced by a leucine. This change was thought to improve the enzyme's ability to hydrolyze carbapenems. In the analysis of the flanking sequences of the genes, Class I integrons were identified in four bacterial strains. The variable regions of these integrons carried three distinct patterns of resistance gene cassettes: ()(), () and ()-. Among these, the strain BJ2326 carried a class I integron that was connected to the downstream IS element to form a composite class I integron structure, additionally carrying the resistance gene . Out of the 223 non-wild-type strains, 127 strains exhibited non-wild-type profiles to the four beta-lactam antibiotics MEM, CAZ, FEP, and TZP, with the combination of MEM+CAZ+FEP being the most prevalent, representing 57.0% of the total. The genes in 241 clinical strains showed diversity. Some genes had a co-transfer risk with the metallo-β-lactamase resistance gene blaIMP-45. Among the 11 newly discovered subtypes, the new subtype OXA-1247 may have carbapenemase activity and potential for horizontal transfer.