AP-HP, Service de Microbiologie, Hôpital Saint-Louis, Paris, France.
Université de Paris, INSERM, IAME, Paris, France.
J Antimicrob Chemother. 2020 Jul 1;75(7):1726-1735. doi: 10.1093/jac/dkaa105.
The resistance to all aminoglycosides (AGs) conferred by 16S rRNA methyltransferase enzymes (16S-RMTases) is a major public health concern.
To characterize the resistance genotype, its genetic environment and plasmid support, and the phylogenetic relatedness of 16S-RMTase-producing Escherichia coli from France.
We screened 137 E. coli isolates resistant to all clinically relevant AGs from nine Parisian hospitals for 16S-RMTases. WGS was performed on clinical isolates with high-level AG resistance (MIC ≥256 mg/L) and their transformants.
Thirty of the 137 AG-resistant E. coli produced 16S-RMTases: 11 ArmA, 18 RmtB and 1 RmtC. The 16S-RMTase producers were also resistant to third-generation cephalosporins (90% due to a blaCTX-M gene), co-trimoxazole, fluoroquinolones and carbapenems (blaNDM and blaVIM genes) in 97%, 83%, 70% and 10% of cases, respectively. Phylogenomic diversity was high in ArmA producers, with 10 different STs, but a similar genetic environment, with the Tn1548 transposon carried by a plasmid closely related to pCTX-M-3 in 6/11 isolates. Conversely, RmtB producers belonged to 12 STs, the most frequent being ST405 and ST complex (STc) 10 (four and four isolates, respectively). The rmtB gene was carried by IncF plasmids in 10 isolates and was found in different genetic environments. The rmtC gene was carried by the pNDM-US plasmid.
ArmA and RmtB are the predominant 16S-RMTases in France, but their spread follows two different patterns: (i) dissemination of a conserved genetic support carrying armA in E. coli with high levels of genomic diversity; and (ii) various genetic environments surrounding rmtB in clonally related E. coli.
16S rRNA 甲基转移酶（16S-RMTases）赋予所有氨基糖苷类（AGs）的耐药性是一个主要的公共卫生关注点。
描述法国产 16S-RMTase 大肠杆菌的耐药基因型、其遗传环境和质粒支持，以及系统发育相关性。
我们筛选了来自巴黎 9 家医院的 137 株对所有临床相关 AGs 均耐药的大肠杆菌，以检测 16S-RMTases。对具有高水平 AG 耐药性（MIC≥256mg/L）的临床分离株及其转化子进行 WGS。
在 137 株 AG 耐药的大肠杆菌中，有 30 株产生了 16S-RMTase：11 株 ArmA、18 株 RmtB 和 1 株 RmtC。16S-RMTase 产生菌对第三代头孢菌素（90%归因于 blaCTX-M 基因）、复方磺胺甲噁唑、氟喹诺酮类和碳青霉烯类（blaNDM 和 blaVIM 基因）的耐药率分别为 97%、83%、70%和 10%。ArmA 产生菌的系统发育多样性较高，有 10 种不同的 ST，但其遗传环境相似，6/11 株菌携带的 Tn1548 转座子与 pCTX-M-3 质粒密切相关。相比之下，RmtB 产生菌属于 12 种 ST，最常见的是 ST405 和 ST 复合群 10（分别为 4 株和 4 株）。rmtB 基因由 10 株菌的 IncF 质粒携带，其遗传环境不同。rmtC 基因由 pNDM-US 质粒携带。
在法国，ArmA 和 RmtB 是主要的 16S-RMTase，但它们的传播遵循两种不同的模式：（i）在具有高度基因组多样性的大肠杆菌中传播携带 armA 的保守遗传支持；（ii）在克隆相关的大肠杆菌中围绕 rmtB 存在各种遗传环境。
