a Department of Bacteriology , Nagoya University Graduate School of Medicine , Nagoya , Japan.
b Department of Obstetrics and Gynecology , Nagoya University Graduate School of Medicine , Nagoya , Japan.
Emerg Microbes Infect. 2019;8(1):2-7. doi: 10.1080/22221751.2018.1557987.
β-Lactam antibiotics are first-line agents for the treatment and prevention of group B Streptococcus (GBS) infections. We previously reported clinical GBS isolates with reduced β-lactam susceptibility (GBS-RBS) and characterized them as harbouring amino acid substitutions in penicillin-binding proteins (PBPs). However, to our knowledge, GBS-RBS clinical isolates have never previously been isolated from pregnant women worldwide. We obtained 477 clinical GBS isolates from vaginal/rectal swabs of 4530 pregnant women in Japan. We determined the MICs of seven β-lactams for all 477 clinical isolates. Five clinical isolates showed reduced ceftibuten susceptibility. For these isolates, we performed sequencing analysis of pbp genes. None of the 477 isolates were non-susceptible to penicillin G, ampicillin, and meropenem. For five isolates, the MICs of ceftibuten were relatively high (64-128 μg/ml). Each of these isolates possessed a single amino acid substitution in PBP2X, and some of the substitutions had been previously found in GBS with reduced penicillin susceptibility. This is the first report of the isolation of clinical GBS-RBS isolates harbouring amino acid substitutions in PBP2X that confer reduced ceftibuten susceptibility from pregnant women.
β-内酰胺类抗生素是治疗和预防 B 组链球菌（GBS）感染的一线药物。我们之前报道了具有降低的β-内酰胺敏感性的临床 GBS 分离株（GBS-RBS），并将其特征描述为青霉素结合蛋白（PBPs）中的氨基酸取代。然而，据我们所知，GBS-RBS 临床分离株从未在全球孕妇中分离出来过。我们从日本 4530 名孕妇的阴道/直肠拭子中获得了 477 株临床 GBS 分离株。我们测定了所有 477 株临床分离株对 7 种β-内酰胺类药物的 MIC 值。有 5 株临床分离株对头孢替坦的敏感性降低。对于这些分离株，我们进行了 pbp 基因的测序分析。没有任何一株分离株对青霉素 G、氨苄西林和美罗培南不敏感。对于 5 株分离株，头孢替坦的 MIC 值相对较高（64-128μg/ml）。这些分离株中的每一株都在 PBP2X 中存在单个氨基酸取代，其中一些取代已在青霉素敏感性降低的 GBS 中发现过。这是首次从孕妇中分离出携带 PBP2X 氨基酸取代导致头孢替坦敏感性降低的临床 GBS-RBS 分离株的报道。
