摘要目的:研究郑州地区妊娠晚期妇女携带红霉素(ERY)耐药B群链球菌(group B Streptococcus，GBS)的耐药表型、分子分型及耐药基因，为GBS感染的预防、控制和治疗提供基础数据。 方法:回顾性收集了河南省妇幼保健院2021—2022年妊娠晚期妇女生殖道分泌物分离获得的86株GBS菌株，使用纸片扩散法筛选出ERY耐药的GBS菌株，对其进行10种抗菌药物敏感性试验；全基因组测序确定其分子分型、克隆群分型、耐药基因等分子特征；比较不同克隆群携带耐药基因情况。结果:筛选出70株ERY耐药的GBS，7.14%(5/70)的菌株对大环内酯-林可酰胺-链阳菌素B (macrolide-lincosamide-streptogramin B, MLSB)具有诱导型耐药(inducible MLSB, iMLSB)表型，84.29%(59/70)的菌株具有结构型耐药(constitutive MLSB, cMLSB)表型，8.57%(6/70)菌株具有对大环内酯类耐药林可酰胺类敏感(macrolides resistance and lincosamide susceptibility, MS)表型。这70株GBS对克林霉素(CLI)、四环素(TE)和左氧氟沙星(LEV)的耐药率分别为91.43%(64/70)，54.29%(38/70)和60.00%(42/70)；菌株呈现多重耐药模式，ERY-CLI-LEV耐药表型占比40.00%(28/70), ERY-CLI-TE耐药表型占比30.00%(21/70)。这70株GBS主要携带有大环内酯/林可酰胺类耐药基因 mreA(100.00%)和 ermB(53/70，75.71%)、氨基糖苷类耐药基因 ant (6)-Ⅰ a(22/70，31.43%)和 aph(3′)-Ⅲ(18/70，25.71%)、四环素类耐药基因 tetM(22/70，31.43%)和 tetO(13/70，18.57%)。这些菌株共检出12个序列型(sequence type，STs)，来源于7个克隆群(clonal complexes，CCs)，CC12占48.57%(34/70)；CC12菌株均携带 ermB未携带 ermA，CC19、CC651菌株中 lsaE、 lunB和 aac (6′)- aph(2″)的携带率、CC651和CC452菌株中 ant (6)-Ⅰ a携带率以及CC19、CC23菌株 mefA和 msrD的携带率显著高于CC12菌株( P<0.001)。 结论:郑州地区ERY耐药GBS呈现多重耐药表型，在分子分型上存在多样性，CC12为本地区主要流行的克隆群。cMLSB表型和 ermB基因是最常见ERY耐药表型和基因型，TE耐药主要由 tetM介导，不同克隆群携带耐药基因也存在一定差异。提示本地区需要密切关注GBS流行病学情况，并在预防治疗时谨慎评估药物的有效性。

abstractsObjective:To investigate the phenotypes, molecular types and drug-resistance genes of erythromycin (ERY)-resistant group B Streptococcus (GBS) in pregnant women in late pregnancy in Zhengzhou and provide basic data for the prevention, control and treatment of GBS infection. Methods:This study retrospectively collected 86 GBS strains isolated from the vaginal secretions of pregnant women in late pregnancy at Maternal and Child Health Hospital of Henan Province from 2021 to 2022. ERY-resistant GBS strains were selected using the ERY disk diffusion method, and their susceptibility to 10 different antibiotics was tested. Whole-genome sequencing was performed to analyze their molecular features including molecular types, clonal complex groups and drug-resistance genes. Drug-resistance genes carried by GBS strains belonging to different clonal complex groups were compared.Results:There were 70 ERY-resistant GBS strains. Among them, 7.14%(5/70) exhibited an inducible resistance phenotype to macrolide-lincosamide-streptogramin B (MLSB) antibiotics; 84.29%(59/70) showed constitutive resistance to MLSB antibiotics; 8.57%(6/70) were resistant to macrolides but susceptible to lincosamides. The resistance rates of these strains to clindamycin (CLI), tetracycline (TE) and levofloxacin (LEV) were 91.43%(64/70), 54.29%(38/70) and 60.00%(42/70), respectively. These ERY-resistant strains exhibited multidrug resistance patterns with 40.00%(28/70) showing ERY-CLI-LEV resistance phenotype and 30.00%(21/70) showing ERY-CLI-TE resistance phenotype. The major drug-resistance genes carried by the 70 GBS strains were macrolide/lincosamide resistance genes mreA (100.00%) and ermB (53/70, 75.71%), aminoglycoside resistance genes ant (6)-Ⅰ a (22/70, 31.43%) and aph(3′)-Ⅲ (18/70, 25.71%), and tetracycline resistance genes tetM (22/70, 31.43%) and tetO (13/70, 18.57%). These strains belonged to 12 sequence types derived from seven clonal complexes (CCs) and 48.57%(34/70) of them were clustered into CC12. All CC12 strains harbored ermB, but none carried ermA. The positive rates of lsaE, lunB, and aac (6′)- aph(2" ) in CC19 and CC651 strains, ant (6)-Ⅰ a in CC651 and CC452 strains, and mefA and msrD in CC19 and CC23 strains were significantly higher than those in CC12 strains ( P<0.001). Conclusions:ERY-resistant GBS in Zhengzhou exhibited diverse drug resistance phenotypes and molecular types. CC12 was the most prevalent clonal complex in this region. The constitutive MLSB resistance phenotype and ermB gene were the most common ERY resistance phenotype and genotype, respectively, and tetM gene was related to tetracycline resistance. Furthermore, the drug-resistance genes varied in GBS strains of different clonal complexes. This study suggested that close attention should be paid to the epidemiological situation of GBS in this region and the effectiveness of antibiotics used for clinical prevention and treatment of GBS infection should be carefully evaluated.