新疆鸡源产超广谱β-内酰胺酶肺炎克雷伯菌流行特征与耐药基因分析OA

To investigate the epidemiological characteristics and antimicrobial resistance genes of extended-spectrum β-lactamase(ESBL)-producing Klebsiella pneumoniae(K.pneumoniae)in layer farms in Xinjiang,fecal samples were collected from six layer farms across five regions.K.pneumoniae isolates were obtained and identified,and ESBL-producing strains were screened using the CLSI-recommended confirmatory test.Antimicrobial susceptibility testing was performed using the broth microdilution method.Whole-genome sequencing was conducted for ESBL-producing isolates from different regions to analyze their resistance genes and plasmid replicon types.A phylogenetic tree based on the core genome was constructed.The results showed that:1)A total of 39 strains of ESBL-producing Klebsiella pneumoniae were identified in 1 155 chickens fecal samples,with a detection rate of 3.5％.2)The resistance rates of all ESBL isolates to tetracycline,cefotaxime,and ciprofloxacin were 89.7％,87.2％and 84.6％,respectively,and they were all susceptible to meropenem.The multi-drug resistant rate was 97.4％.3)Among the 35 ESBL-producing strains from different regions,66 resistance genes across 12 categories were detected.The most prevalent genes were blaSHV,oqxA,and oqxB(all 97.1％).A total of 14 strains were found to carry the tmexCD-TOprJ efflux pump gene conferring tigecycline resistance,mainly distributed in ST37(11/14).4)Twelve plasmid replicon types were identified;82.9％(29/35)of isolates harbored at least one replicon,with IncFIB(K)being the most common(72.4％).5)Twelve sequence types(STs)were identified among the 35 strains,reflecting high genetic diversity.No evidence of cross-regional clonal dissemination was found;However,tight clustering of ST37,ST307,ST5116,and ST200 was observed within the Tacheng farm.In conclusion,although the detection rate of ESBL-producing K.pneumoniae in Xinjiang layer farms was relatively low,the isolates exhibited broad resistance spectra,carried multiple resistance genes and plasmid replicons,and showed evidence of clonal transmission in certain farms.These results highlight the need for strengthened regional monitoring and control measures for antimicrobial-resistant bacteria.