佛山市顺德区淋病奈瑟菌头孢曲松低敏菌株mtrR基因检测及流行病学研究

mtrR gene detection and epidemiological study of hyposensitive strains of gonococcal ceftriaxone in Shunde area,Foshan city

目的为了解顺德地区淋病奈瑟菌mtrR基因突变情况,探索其基因突变与头孢曲松低敏之间的联系。方法去本研究通过分离培养临床送检标本中的淋病奈瑟菌,收集到146株淋病奈瑟菌株。通过纸片扩散法(K-B)检测6种药物(头孢曲松、环丙沙星、诺氟沙星、青霉素、四环素和大观霉素)的药敏情况;用琼脂稀释法测定头孢曲松的抑制细菌可见生长的最低药物浓度(MIC)值,根据MIC结果将淋病奈瑟菌分为头孢曲松敏感组和头孢曲松低敏组。提取头孢曲松敏感组与低敏组淋病奈瑟菌全基因组核酸,扩增mtrR基因,分离纯化后测序,比较2组淋病奈瑟菌mtrR基因突变情况;分析基因突变与头孢曲松低敏之间的相关性,探索其耐药机制。结果本研究中淋病奈瑟菌对抗生素耐药率依次为青霉素72%、环丙沙星92%、四环素78%、诺氟沙星75%、头孢曲松和大观霉素未检出耐药株。根据MIC结果,头孢曲松低敏菌株有12株(8%),高敏菌株134株(92%)。基因测序显示顺德区淋病奈瑟菌mtrR基因主要存在A39T、G45D、H105Y三种类型的突变12株头孢曲松低敏组淋病奈瑟菌的mtrR基因中存在2个或2个以上的基因突变位点。结论本地区淋病奈瑟菌对头孢曲松以及大观霉素敏感性较高,可作为治疗首选药物。mtrR基因突变以A39T、G45D、H105Y基因型为主,头孢曲松低敏淋球菌同时存在2个或2个以上的基因突变位置,需扩大淋病筛查和耐药监测,更好地防控淋病。

Objective To understand the mtrR gene mutation of Neisseria gonorrhoeae in Shunde area and to explore the connection between its gene mutation and ceftriaxone hyposensitivity.Methods In this study,146 gonococcal strains were collected by isolating and culturing gonococci from clinical specimens.The drug susceptibility of six drugs(including ceftriaxone,ciprofloxacin,norfloxacin,penicillin,tetracycline and spectinomycin)was detected by K-B method(disk diffusion method);ceftriaxone was determined by agar dilution method according to the MIC value,gonococci were divided into ceftriaxone-sensitive group and ceftriaxone-hyposensitive group.We extracted the whole genome nucleic acid of Neisseria gonorrhoeae from the ceftriaxone-sensitive group and the low-sensitivity group,amplified the mtrR gene,isolated and purified it,and sequenced it to compare the mtrR gene mutations of the two groups of gonococci.The correlation between gene mutations and ceftriaxone hyposensitivity was also analyzed.We explored its resistance mechanism.Results In this study,the antibiotic resistance rates of gonococci in this study were penicillin 72%,ciprofloxacin 92%,tetracycline 78%,norfloxacin 75%,and no resistant strains were detected to ceftriaxone and spectinomycin.According to the MIC results,there were 12 strains with low sensitivity to ceftriaxone,accounting for 8%,and 134 strains with high sensitivity to ceftriaxone,accounting for 92%.Gene sequencing shows that there are three main types of mutations in the gonococcal mtrR gene in Shunde:A39T,G45D,and H105Y.There are two or more gene mutation sites in the mtrR gene of 12 strains of gonococci in the cefriaxone hyposensitive group.ConclusionNeisseria gonorrhoeae in this area are highly sensitive to ceftriaxone and spectinomycin,which can be used as the first-choice drugs for treatment.The mtrR gene mutations of gonorrhea in Shunde are mainly A39T,G45D,and H105Y genotypes.Two or more gene mutations exist in ceftriaxone-low-susceptible gonococci at the same time.Gonorrhea screening and drug resistance monitoring need to be expanded for better prevention and control of gonorrhea.