新兴ST950型肺炎克雷伯菌的耐药性、毒力及基因组特征研究OA

Objective To characterize the antimicrobial resistance,virulence traits,biological characteristics,and population structure of the ST950 KP clone.Methods A representative ST950 strain,KP230524-43,isola-ted from the urine of a patient with a UTI,was identified using the VITEK-2 Compact automated microbiology system.Its cytotoxicity and biofilm formation capacity were assessed via lactate dehydrogenase(LDH)release assay and crystal violet staining,respectively.The genomic DNA of klebsiella pneumoniae KP230524-43 was ex-tracted and subjected to whole-genome sequencing analysis.Phylogenetic tree analysis was performed using a to-tal of 23 klebsiella pneumoniae strains of sequence type 950(ST950),including 22 known sequences obtained from the NCBI database.Results KP230524-43 exhibited significant cytotoxicity,strong biofilm formation,and resistance to β-lactam antibiotics.Unlike classical hypervirulent strains,all ST950 isolates lacked common hy-pervirulence markers(e.g.,rmpA,peg-344,iucA).However,they consistently carried the enterobactin syn-thesis and transport genes entAB and fepC,the pilus synthesis gene cluster ecpABCDR,and the gene encoding outer membrane protein A(ompA).The astA gene,encoding the EAST1 toxin,was detected in some ST950 strains,including KP230524-43.Over half of the strains harbored carbapenemase or extended-spectrum β-lacta-mase resistance genes.Furthermore,our analysis revealed that ST950 strains have emerged in multiple coun-tries,indicating a potential for cross-border transmission.Conclusion The ST950 clone represents an emerging,potentially high-risk lineage of K.pneumoniae characterized by a distinct virulence profile,robust biofilm-forming capacity,and multidrug resistance.Enhanced surveillance,molecular epidemiological studies,and targeted in-fection control measures are urgently needed.