1Laboratory of Clinical Microbiology and Infectious Diseases, Department of Pulmonary and Critical Care Medicine, Center for Respiratory Diseases, China-Japan Friendship Hospital; National Clinical Research Center of Respiratory Diseases, Beijing,100029, PR China.
2Department of Laboratory Medicine, Xiamen Maternal and Child Health Hospital, Xiamen, 361003, PR China.
J Med Microbiol. 2018 Nov;67(11):1551-1559. doi: 10.1099/jmm.0.000849. Epub 2018 Sep 28.
Group B Streptococcus (GBS) is one of the major pathogens in severe materno-neonatal infections. We aimed to describe the clinical and molecular characteristics of GBS isolates causing infections in 45 maternal and 50 neonatal subjects, collected from eight healthcare centres in mainland China over the period 2010- 2017.
The phenotypic and genotypic features of the GBS isolates, including capsular polysaccharide (cps) serotypes, pilus island (PI) genes and antibiotic resistance profiles and genes, were characterized by both conventional and molecular methods. The clonal relationship between these strains was investigated using multilocus sequence typing (MLST).
Of the 95 isolates, the predominant serotypes were III (51, 53.7 %), V (13, 13.7 %) and Ib (13, 13.7 %). All GBS strains carried at least one pilus island, with 32.6 % carrying PI-2b and 67.4 % PI-2a, singly or in combination. The most frequently-detected pilus island pattern was the combination of PI-1 and PI-2a, accounting for 56.8 % (54 isolates), followed by PI-1 combined with PI-2b (28, 29.5 %), PI-2a (10, 10.5 %) and PI-2b (3, 3.2 %). The strains were classified into 17 individual sequence types, and further clustered into six clonal complexes (CCs). A high prevalence of CC17/PI-1 and PI-2b (17, 34.0 %) was detected in 50 GBS isolates causing neonatal infections. No strain was resistant to penicillin, ampicillin, ceftriaxone or vancomycin, whereas 78.9, 76.8 and 81.5 % were resistant to erythromycin, clindamycin and tetracycline, respectively.
Our study highlights the high genotypic diversity of GBS strains causing materno-neonatal infections, and the CC17/PI-1 and PI-2b sublineages should be noted in neonatal infections.
B 群链球菌（GBS）是严重母婴感染的主要病原体之一。本研究旨在描述 2010 年至 2017 年期间，中国大陆 8 家医疗中心收集的 45 例产妇和 50 例新生儿感染的 GBS 分离株的临床和分子特征。
采用常规和分子方法，对 GBS 分离株的表型和基因型特征，包括荚膜多糖（cps）血清型、菌毛岛（PI）基因和抗生素耐药谱和基因进行了描述。采用多位点序列分型（MLST）分析这些菌株之间的克隆关系。
95 株分离株中，优势血清型为 III 型（51 株，占 53.7%）、V 型（13 株，占 13.7%）和 Ib 型（13 株，占 13.7%）。所有 GBS 菌株均携带至少一种菌毛岛，其中 32.6%携带 PI-2b，67.4%携带 PI-2a，单独或组合携带。最常见的菌毛岛模式是 PI-1 和 PI-2a 的组合，占 56.8%（54 株），其次是 PI-1 与 PI-2b 组合（28 株，占 29.5%）、PI-2a（10 株，占 10.5%）和 PI-2b（3 株，占 3.2%）。这些菌株分为 17 个独立的序列型，进一步聚类为 6 个克隆复合体（CC）。在 50 株引起新生儿感染的 GBS 分离株中，高度流行 CC17/PI-1 和 PI-2b（17 株，占 34.0%）。所有菌株均对青霉素、氨苄西林、头孢曲松和万古霉素敏感，而 78.9%、76.8%和 81.5%的菌株分别对红霉素、克林霉素和四环素耐药。
本研究强调了引起母婴感染的 GBS 菌株的高度基因多样性，应注意新生儿感染中的 CC17/PI-1 和 PI-2b 亚系。
