广西宋内志贺菌药敏特性及ESBLs基因检测分析

目的了解广西地区宋内志贺菌的药敏特性及携带超广谱β-内酰胺酶(ESBLs)基因与型别特征,为临床合理用药和控制耐药性的传播提供科学依据。方法采用微量肉汤稀释法对宋内志贺菌分离株进行药物敏感试验;采用PCR方法和毛细管电泳方法检测菌株携带相关ESBLs基因;采用近邻相接法构建系统进化树,分析菌株CTX-M型基因型别;对菌株携带ESBLs基因与特定抗菌药物耐药性的关系进行统计学分析。结果90株宋内志贺菌对环丙沙星敏感率为86.67%,无耐药现象;头孢曲松耐药率为96.67%,阿奇霉素耐药率为96.67%,多重耐药率为98.89%。90株宋内志贺菌中50株检出blaCTX-M-9 group基因,检出率为55.56%,经系统发育分析均为CTX-M-14亚型;1株检出blaTEM基因,检出率为1.11%;未检出blaCTX-M-1 group,blaCTX-M-2 group,blaCTX-M-8 group,blaCTX-M-25 group和blaOXA,blaSHV,blaNDM,blaVIM等β-内酰胺酶基因。blaCTX-M-14基因阳性菌株与blaCTX-M-14基因阴性菌株对头孢噻肟的耐药率差异无统计学意义(χ²=0.000,P>0.05);携带blaTEM基因的菌株对头孢他啶不耐药。结论广西地区的宋内志贺菌对主要治疗药物头孢曲松高度耐药,且多重耐药现象严重;菌株普遍携带ESBLs基因,主要为CTX-M-14亚型;携带单一型别的ESBLs基因与菌株对特定β-内酰胺类抗菌药物耐药无明显关联。

Analysis of the antimicrobial susceptibility and ESBLs genes of Shigella sonnei strains isolated in Guangxi

Objectives To analyze the antimicrobial susceptibility,harboring of ESBL genes,and genotype characteristics of Shigella sonnei strains isolated in Guangxi in the hopes of providing a scientific basis to guide clinical treatment and control drug resistance.Methods An antimicrobial susceptibility test of confirmed S.sonnei strains was conducted using the mini broth dilution method,and the minimal inhibitory concentration(MIC)of the strains to each antibiotic was determined.Specific primers were designed and amplified with PCR,and then capillary electrophoresis was performed to determine whether ESBL genes were present in the PCR products.The PCR products were sequenced,the nucleotide sequence of the blaCTX-M gene was determined using the software SeqMan,and then a BLAST comparison was performed on the NCBI website.A phylogenetic tree was constructed with the software MEGA 7 using the NJ method,and then the genetic relationship of the blaCTX-M gene cluster was analyzed among the strains.The relationship between the ESBL genes harbored by the strains and resistance to specific antibiotics was statistically analyzed using a chi-square test.Results A total of 90 strains of Shigella sonnei had no resistance to ciprofloxacin and a susceptibility of 86.67%.The strains were resistant to ceftriaxone at a rate of 96.67%.The strains were resistant to azithromycin at a rate of 96.67%.Of the strains,98.89%had multidrug resistance.Of the 90 strains of Shigella sonnei,50 harbored a blaCTX-M-9 group gene at a rate of 55.56%,and the subtype of the gene was determined to be the CTX-M-14 subtype according to phylogenetic analysis.One strain harbored the blaTEM gene,so the gene was detected at a rate of 1.11%.blaCTX-M-1 group genes,blaCTX-M-2 group genes,blaCTX-M-8 group genes,blaCTX-M-25 group genes,blaNDM genes,and otherβ-lactamase genes were not detected in the strains.blaCTX-M-14 gene-positive strains and blaCTX-M-14 gene-negative strains did not differ significantly in their resistance to cefotaxime,and the strain harboring the blaTEM gene was not resistant to ceftazidime.Conclusion S.sonnei in Guangxi is highly resistant to the main therapeutic drug ceftriaxone,and it is highly multidrug-resistant.The strains generally harbor ESBL genes,and CTX-M-14 subtype was the main subtype.There was no significant correlation between harboring a single type of ESBL gene and resistance to specificβ-lactam antibiotics.