Graduate School of Medicine, Nagoya University, Aichi, Japan; Antimicrobial Resistance Research Center, National Institute of Infectious Diseases, Tokyo, Japan.
Antimicrobial Resistance Research Center, National Institute of Infectious Diseases, Tokyo, Japan.
J Glob Antimicrob Resist. 2020 Dec;23:456-465. doi: 10.1016/j.jgar.2020.10.021. Epub 2020 Nov 17.
The Escherichia coli O25-ST131 clone is responsible for global dissemination of the bla gene. However, the prevalence of this clone in the digestive tract, devoid of antimicrobial selection, and its molecular epidemiology remain unclear. In this study, we examined the origin of bla-positive E. coli O25-ST131 and its distribution.
We separately sequenced the chromosomal and plasmid genomes of 50 E. coli O25 isolates obtained from faecal samples of patients with diarrhoea in Japan.
Although 36 (72%) of 50 E. coli O25 isolates were ST131, only 6 harboured bla. According to the fimH and ybbW sequences and fluoroquinolone susceptibility, H30R1 isolates were dominant (27/36; 75%) and possessed IncFII-FIA-FIB with FAB formula subtype F1:A2:B20 plasmids at a high frequency (24/27; 89%). The F1:A2:B20 plasmids possessed more resistance genes such as bla, aminoglycoside resistance genes and trimethoprim/sulfamethoxazole resistance genes compared with non-F1:A2:B20 plasmids. In contrast, only one bla gene was located on the F1:A2:B20 plasmids, whereas the other three were located on IncFII (F4:A-:B-) (n = 1) and IncZ (n = 2) plasmids. Two H30Rx-ST131 isolates harboured bla: one was on the chromosome and the other on the IncFIA-R plasmid. The stability and conjugation ability of the F1:A2:B20 plasmids were compared with those of non-F1:A2:B20 plasmids, which revealed higher stability but lower conjugative ability.
These results suggest that E. coli H30R1-ST131 is a multidrug-resistant clone containing several resistance genes in the F1:A2:B20 plasmid, which were widely distributed before the acquisition of bla.
大肠杆菌 O25-ST131 克隆负责 bla 基因的全球传播。然而，这种克隆在没有抗菌选择的消化道中的流行情况及其分子流行病学仍不清楚。在本研究中，我们研究了 bla 阳性大肠杆菌 O25-ST131 的起源及其分布。
我们分别对从日本腹泻患者粪便样本中分离的 50 株大肠杆菌 O25 分离株的染色体和质粒基因组进行测序。
尽管 50 株大肠杆菌 O25 分离株中有 36 株（72%）为 ST131，但只有 6 株含有 bla。根据 fimH 和 ybbW 序列和氟喹诺酮敏感性，H30R1 分离株占主导地位（27/36；75%），并高频携带 IncFII-FIA-FIB 型 FAB 亚型 F1:A2:B20 质粒（24/27；89%）。与非 F1:A2:B20 质粒相比，F1:A2:B20 质粒具有更多的耐药基因，如 bla、氨基糖苷类耐药基因和复方磺胺甲噁唑耐药基因。相比之下，只有一个 bla 基因位于 F1:A2:B20 质粒上，而其他三个位于 IncFII（F4:A-:B-）（n = 1）和 IncZ（n = 2）质粒上。两个 H30Rx-ST131 分离株含有 bla：一个位于染色体上，另一个位于 IncFIA-R 质粒上。与非 F1:A2:B20 质粒相比，F1:A2:B20 质粒的稳定性和接合能力更高，但接合能力较低。
这些结果表明，大肠杆菌 H30R1-ST131 是一种含有 F1:A2:B20 质粒中多个耐药基因的多药耐药克隆，在获得 bla 之前就已广泛分布。
