Department of Bacteriology II, National Institute of Infectious Diseases, 4-7-1 Musashi-murayama, Tokyo 208-0011, Japan.
J Antimicrob Chemother. 2012 Apr;67(4):849-56. doi: 10.1093/jac/dkr546. Epub 2011 Dec 29.
Multiple group B Streptococcus (GBS) isolates with reduced penicillin susceptibility (PRGBS) were recovered from several patients, hence a probable nosocomial transmission of PRGBS in a hospital setting was suspected.
Ten PRGBS recovered from eight patients in a general hospital were characterized. Sequence analysis of genes for penicillin-binding proteins (PBPs) and quinolone resistance-determining regions (QRDRs) of gyrA, gyrB and parC was performed, and the macrolide resistance genes were detected by PCR. Genetic relatedness among the isolates was examined by PFGE and multilocus sequence typing.
All the PRGBS had the key amino acid substitution V405A, together with F395L, R433H, H438Y and G648A in PBP 2X and T567I in PBP 2B. A 23S rRNA methylase gene, erm(B), was also found in all 10 PRGBS strains. PFGE analysis revealed considerable genetic relatedness among the isolates. Isolates of pulsotype I were obtained from four patients in ward A and one patient in ward B, while isolates of pulsotypes II and III were obtained from two patients in ward B and one patient in ward C, respectively. Isolates of pulsotype I were resistant to levofloxacin (MIC >8 mg/L) and had the following amino acid substitutions in the QRDRs: S81L in GyrA, E476K in GyrB and S79Y in ParC. However, pulsotype II strains resistant to levofloxacin (MIC 8 mg/L) had no change in GyrA, but changes in GyrB (E476K) and ParC (S79Y). All 10 PRGBS strains belonged to serotype VI and ST458 (where ST stands for sequence type).
This is the first description of the nosocomial spread of multidrug-resistant PRGBS strains belonging to the genetic lineage ST458.
从几位患者中分离出了具有较低青霉素敏感性的多种 B 群链球菌（GBS）分离株（PRGBS），因此怀疑在医院环境中发生了 PRGBS 的可能的医院内传播。
对来自一家综合医院的 8 位患者的 10 株 PRGBS 进行了特征分析。对青霉素结合蛋白（PBP）的基因和 gyrA、gyrB 和 parC 的喹诺酮耐药决定区（QRDR）进行了序列分析，并通过 PCR 检测了大环内酯类耐药基因。通过 PFGE 和多位点序列分型检查了分离株之间的遗传相关性。
所有 PRGBS 均具有关键的氨基酸取代 V405A，同时在 PBP 2X 中具有 F395L、R433H、H438Y 和 G648A，在 PBP 2B 中具有 T567I。在所有 10 株 PRGBS 中还发现了 23S rRNA 甲基化酶基因 erm（B）。PFGE 分析显示分离株之间存在相当大的遗传相关性。I 型脉冲型分离株来自 A 病房的 4 位患者和 B 病房的 1 位患者，而 II 型和 III 型脉冲型分离株分别来自 B 病房的 2 位患者和 C 病房的 1 位患者。I 型脉冲型分离株对左氧氟沙星（MIC>8mg/L）具有耐药性，并且在 QRDR 中具有以下氨基酸取代：GyrA 中的 S81L、GyrB 中的 E476K 和 ParC 中的 S79Y。但是，对左氧氟沙星（MIC 8mg/L）具有耐药性的 II 型菌株在 GyrA 中没有变化，但是在 GyrB（E476K）和 ParC（S79Y）中发生了变化。所有 10 株 PRGBS 均属于 VI 型和 ST458 血清型（其中 ST 代表序列类型）。
这是首次描述属于遗传谱系 ST458 的多药耐药 PRGBS 菌株的医院内传播。
