Department of Microbiology, Sapporo Medical University School of Medicine, Sapporo, Japan.
Chemotherapy. 2012;58(1):52-9. doi: 10.1159/000336129. Epub 2012 Feb 15.
Fluoroquinolone-resistant and extended-spectrum β-lactamase (ESBL)-carrying multidrug-resistant Escherichia coli have become severely problematic. In particular, a lineage of multilocus sequence-type ST131 which belongs to O25:H4 and carries ESBL CTX-M-15 has spread worldwide.
Fluoroquinolone-resistant E. coli strains were isolated from various clinical specimens in a commercial clinical laboratory in 2008 and 2009 in Hokkaido Prefecture, Japan.
Among 478 clinical isolates, 112 strains (23.4%) showed levofloxacin (LVX) resistance. About 80% of the fluoroquinolone-resistant strains (88 strains) showed common features, namely O25:H4-ST131, phylogenetic group B and the same mutation pattern in quinolone resistance-determining regions. Pulsed field gel electrophoresis patterns suggested numerous lineages of O25:H4-ST131. The fluoroquinolone-resistant strains, including strains of O25:H4-ST131 and other types, more frequently shared CTX-type ESBL genes than did fluoroquinolone-susceptible strains. The ESBL genes fell into the CTX-M-9 and CTX-M-2 groups. CTX-M-15 (CTX-M-1 group) was not found among any of the strains isolated in this study. Sitafloxacin showed markedly potent activity against E. coli isolates compared with LVX, ciprofloxacin and ulifloxacin.
The most prevalent fluoroquinolone-resistant strains of E. coli isolated in Hokkaido Prefecture, Japan, are O25:H4-ST131. However, similar to other areas of Japan, the ST131 clones represent distinct lineages from the general worldwide dispersal of multidrug-resistant clones which carry CTX-M-15.
氟喹诺酮耐药和超广谱β-内酰胺酶（ESBL）携带的多药耐药大肠杆菌已成为严重问题。特别是属于 O25：H4 并携带 ESBL CTX-M-15 的多序列型 ST131 谱系已在全球范围内传播。
2008 年至 2009 年，在日本北海道的一家商业临床实验室中，从各种临床标本中分离出氟喹诺酮耐药大肠杆菌菌株。
在 478 株临床分离株中，有 112 株（23.4%）对左氧氟沙星（LVX）耐药。约 80%的氟喹诺酮耐药株（88 株）具有共同特征，即 O25：H4-ST131、进化群 B 和喹诺酮耐药决定区的相同突变模式。脉冲场凝胶电泳图谱表明存在许多 O25：H4-ST131 谱系。氟喹诺酮耐药株，包括 O25：H4-ST131 株和其他类型，比氟喹诺酮敏感株更频繁地共享 CTX 型 ESBL 基因。ESBL 基因属于 CTX-M-9 和 CTX-M-2 组。在本研究中分离的菌株中未发现 CTX-M-15（CTX-M-1 组）。与 LVX、环丙沙星和左氧氟沙星相比，司他沙星对大肠杆菌分离株表现出明显的活性。
在日本北海道分离的最常见的氟喹诺酮耐药大肠杆菌菌株是 O25：H4-ST131。然而，与日本其他地区一样，ST131 克隆代表与携带 CTX-M-15 的多药耐药克隆在全球广泛传播的不同谱系。
