孕晚期B族链球菌感染菌株基因分型及其耐药性

Genotypes and drug resistance of group B Streptococcus causing infection in late pregnant women

目的观察孕晚期B族链球菌(Group B streptococcus,GBS)感染孕妇临床诊断、菌株基因分型、耐药性及临床结局分析。方法选取2018年2月-2019年3月在人民医院产科就诊的4 127例待产孕妇作为研究对象,入院时取阴道及直肠分泌物进行细菌培养,对菌株进行基因分型及耐药性分析,将B族链球菌阳性产妇作为试验组,阴性产妇作为对照组,分析B族链球菌感染对产妇临床结局的影响。结果 4 127份待检样本中,GBS阳性样本332例,GBS感染率为8.04%。试验组孕妇孕前BMI高于对照组(P<0.05);多位点序列分型(Multilocus sequence typing,MLST)分型结果显示,2株样本分型失败,330株GBS菌株共鉴定出12种分型,排名前三的分别为ST19型、ST17型、ST12型,分别占19.09%、16.36%、13.64%。本次试验共鉴定出6种CC克隆群,排名前三的分别为CC19、CC103、CC17,分别占24.70%、16.57%、16.27%。GBS菌株对氨苄青霉素、头孢噻肟敏感度最高,为100.00%;对红霉素、四环素、克林霉素敏感性较低;不同MLST分型菌株对红霉素、四环素、克林霉素、左氧氟沙星、阿奇霉素的耐药率差异有统计学意义(P<0.05);试验组胎膜早破、新生儿感染、羊水污染、羊膜炎、胎儿窘迫、产褥期感染的发生率高于对照组(P<0.05)。结论孕前肥胖者更容易发生GBS感染,感染可增加孕晚期孕妇妊娠不良结局的风险。不同MLST分型的GBS毒株耐药性存在差异,青霉素类药物敏感性较好,可作为临床用药的首选方案。

OBJECTIVE To observe clinical diagnosis of with group B Streptococcal(GBS) infection, analysis of strain genotyping, drug resistance and clinical outcomes in late pregnant women. METHODS During the period from February 2018 to March 2019, 4 127 pre-delivery pregnant women who were treated in obstetrics department of the hospital were enrolled. At admission, vaginal and rectal secretions were taken for bacterial culture;genotyping and drug resistance analysis were performed on strains. The positive GBS pregnant women were divided into the observation group, whereas negative GBS pregnant women were enrolled as the control group. The effects of GBS infection on maternal clinical outcomes were analyzed. RESULTS Among 4 127 samples to be tested, there were 332 cases with positive GBS, with the GBS infection rate of 8.04%. The progestational BMI in the observation group was significantly higher than that in the control group(P<0.05). The results of MLST typing showed that there were 2 strains isolated from the samples with failure typing. Among 330 GBS strains, there were classified as 12 types. And the top three were ST19, ST17 and ST12, accounting for 19.09%, 16.36% and 13.64%, respectively. There were 6 kinds of CC clones in this experiment. The top three were CC19, CC103 and CC17, accounting for 24.70%, 16.57% and 16.27%, respectively. GBS strains showed the highest frequency of ampicillin and cefotaxime(100%) susceptibility, and were less sensitive to erythromycin, tetracycline and clindamycin. There were significant differences of resistance to erythromycin, tetracycline, clindamycin, levofloxacin and azithromycin between different MLST typing strains(P<0.05). The incidence of premature rupture of membranes, neonatal infection, amniotic fluid contamination, amniotitis, fetal distress and puerperal infection in the observation group was significantly higher than that in the control group(P<0.05). CONCLUSION Progestation obesity was more likely to cause GBS infection. The infection may increase the risk of adverse pregnancy outcomes in late pregnant women. The differences in the drug resistance of different MLST typing of GBS strains were remarkable. The sensitivity of GBS strains to penicillins was relatively better, which can be applied as the first choice for clinical medication.