孕晚期无乳链球菌感染的血清型耐药性及分子遗传背景特征

Serotype drug resistance and molecular genetic background characteristics of Streptococcus agalactiae infection in late pregnancy

目的 探讨并分析孕晚期无乳链球菌(GBS)感染的血清型耐药性及分子遗传背景特征。方法 前瞻性选取收治的孕晚期(35~37周)孕妇为研究对象,采集阴道分泌物,采用荧光定量PCR法和显色培养加鉴定法筛查GBS,GBS阳性患者设为观察组(n=50),GBS阴性患者设为对照组(n=50)。分析荧光定量聚合酶链反应(polymerase chain reaction, PCR)法和显色培养加鉴定法阳性检出率,同时对观察组患者的GBS定植菌株进行血清型耐药性及分子遗传背景特征分析,分析GBS定植菌株的流行病学特点,分析血清型与抗菌药物耐药、血清型与毒力基因、血清型与耐药基因的相关性。结果 观察组阴道分娩人数低于对照组,剖宫产人数、胎儿窘迫、胎膜早破、羊水污染发生率高于对照组(P>0.05)。观察组早产人数以及Apgar评分均明显高于对照组(P<0.05)。GBS阳性患者的耐药情况:GBS对青霉素、万古霉素、氨苄西林、头孢曲松敏感,对左氧氟沙星(48.00%)、克林霉素(38.00%)、红霉素(72.00%)、四环素(86.00%)均表现出不同程度的耐药性。50例GBS阳性孕妇阴道定植的GBS共发现5个血清型,其中Ⅲ型有27株,占比54.00%、Ⅰb型有9株,占比18.00%、Ⅰa有5株,占比10.00%、Ⅴ型有5株,占比10.00%、Ⅱ型有4株,占比8.00%。50株GBS抗生素敏感性检测结果显示,不同血清型菌株对青霉素、万古霉素、氨苄西林、头孢曲松敏感。比较不同血清型对抗生素的敏感性发现:血清Ⅲ型菌株对左氧氟沙星的耐药率明显高于其他菌株。血清Ⅲ、Ⅰa型菌株对克林霉素的耐药率明显高于其他菌株。血清Ⅰb、Ⅰa型菌株对红霉素的耐药率明显高于其他菌株。血清Ⅰb、Ⅰa型菌株对四环素的耐药率明显高于其他菌株。GBS阳性孕产妇主要的耐药模式为:红霉素-克林霉素-四环素、红霉素-克林霉素-氯霉素、红霉素-克林霉素-四环素-氯霉素、红霉素-克林霉素-四环素-左氧氟沙星4种。其中Ⅲ型血清对抗生素耐药性阳性率最高,耐药阳性对比红霉素>四环素>左氧氟沙星>克林霉素。耐药基因中,tetM、mefA/E、tetO/ermB基因阳性率排名前三,tetM基因在血清Ⅰb型菌株的阳性率最高,mefA/E基因在血清Ⅲ型菌株的阳性率最高,tetO基因在血清Ⅰa型菌株的阳性率最高,ermB基因在血清Ⅱ型菌株的阳性率最高。毒力基因中,epsilon基因阳性率最高,epsilon基因在血清型Ⅰb的菌株阳性率最高。结论 孕晚期GBS感染的血清分型以Ⅲ型、Ⅰb型、Ⅰa型、Ⅴ型、Ⅱ型常见,GBS对青霉素、万古霉素、氨苄西林、头孢曲松敏感,对红霉素、四环素耐药程度高。其中Ⅲ型血清对抗生素耐药性阳性率最高,tetM、mefA/E、tetO/ermB基因阳性率排名前三,毒力基因中,epsilon基因阳性率最高。

Objective To analyze the serotype drug resistance and molecular genetic background characteristics of Streptococcus agalactiae(GBS)infection in the third trimester of pregnancy.Methods The pregnant women in the third trimester of pregnancy(35-37 weeks)admitted to hospital were prospectively selected.Vaginal secretions were collected and GBS was screened by fluorescence quantitative PCR and chromogenic culture plus identification.The patients with GBS positive were set as the study group(n=50)and those with GBS negative were set as the control group(n=50).The positive detection rates of fluorescent quantitative polymerase chain reaction(PCR)method and chromogenic culture plus identification method were analyzed.Meanwhile,the characteristics of serotype drug resistance and molecular genetic background of GBS colonized strains of patients in the study group were analyzed,and the epidemiological characteristics of GBS colonized strains were analyzed.The correlations between serotype and antibiotic resistance,serotype and virulence gene,serotype and drug resistance gene were analyzed.Results The number of vaginal deliveries in the study group was lower than that in the control group,while the number of cesarean section,fetal distress,premature rupture of membranes and amniotic fluid pollution were higher than those in the control group(P>0.05).The number of premature births and Apgar score in the study group were significantly higher than those in the control group(P<0.05).Drug resistance of GBS-positive patients showed that GBS was sensitive to penicillin,vancomycin,ampicillin and ceftriaxone;and showed different degrees of drug resistance to levofloxacin(48.00%),clindamycin(38.00%),erythromycin(72.00%)and tetracycline(86.00%).Five serotypes of GBS were found in vaginal colonization of 50 GBS positive pregnant women,including 27 strains of TypeⅢ(54.00%),9 strains of TypeⅠb(18.00%),5 strains of TypeⅠa(10.00%),5 strains of TypeⅤ(10.00%)and 4 strains of TypeⅡ(8.00%).The results of antibiotic sensitivity test of 50 GBS strains showed that different serotype strains were sensitive to penicillin,vancomycin,ampicillin and ceftriaxone.The drug resistance rate of SerotypeⅢstrains to levofloxacin was significantly higher than that of other strains.The drug resistance rates of SerotypeⅢandⅠa strains to clindamycin were significantly higher than those of other strains.The resistance rate of SerotypeⅠb andⅠa strains to erythromycin was significantly higher than that of other strains.The resistance rate of SerotypeⅠb andⅠa strains to tetracycline was significantly higher than that of other strains.The main drug resistance patterns of GBS positive pregnant women were erythromycin-clindamycin-tetracycline,erythromycin-clindamycin-chloramphenicol,erythromycin-clindamycin-tetracycline-chloramphenicol,and erythromycin-clindamycin-tetracycline-levofloxacin.Among them,the positive rate of antibiotic resistance in TypeⅢwas the highest,and the positive contrast of drug resistance was erythromycin>tetracycline>levofloxacin>clindamycin.Among the drug-resistant genes,the positive rates of tetM,mefA/E and tetO/ermB ranked in the top three.And the positive rate of tetM gene in SerotypeⅠb strain was the highest;that of mefA/E gene in SerotypeⅢstrain was the highest;that of tetO gene in SerotypeⅠa strain was the highest and that of ermB gene in serum typeⅡstrain was the highest.Among virulence genes,epsilon gene had the highest positive rate,and epsilon gene had the highest positive rate in serotypeⅠb strains.Conclusion TypeⅢ,TypeⅠb,TypeⅠa,TypeⅤand TypeⅡof GBS infection in the third trimester of pregnancy are common.GBS is sensitive to penicillin,vancomycin,ampicillin and ceftriaxone,and highly resistant to erythromycin and tetracycline.Among them,the positive rate of antibiotic resistance in TypeⅢserum is the highest,and the positive rates of tetM,mefA/E and tetO/ermB genes rank in the top three.Among virulence genes,epsilon gene has the highest positive rate.