Gomi Ryota, Matsumura Yasufumi, Tanaka Michio, Ihara Masaru, Sugie Yoshinori, Matsuda Tomonari, Yamamoto Masaki
Department of Environmental Engineering, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, 615-8540, Kyoto, Japan.
Department of Clinical Laboratory Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-kawahara-cho, Sakyo-ku, 606-8507, Kyoto, Japan.
J Antimicrob Chemother. 2022 Apr 27;77(5):1237-1246. doi: 10.1093/jac/dkac029.
Carbapenemase-producing Enterobacterales (CPE) pose serious threats to public health. Compared with clinical CPE, the genetic characteristics of environmental CPE are not well understood. This study aimed to characterize the genetic determinants of carbapenem resistance in CPE isolated from environmental waters in Japan.
Eighty-five water samples were collected from rivers and a lake in Japan. CPE were identified using selective media, and genome sequencing was performed for the obtained isolates (n = 21).
Various rare/novel carbapenemases were identified: GES-5 in Raoultella planticola (n = 1), FRI-8 and FRI-11 in Enterobacter spp. (n = 8), IMI-22 and IMI-23 in Serratia ureilytica (n = 3), and SFC-1, SFC-2 and SFH-1 in Serratia fonticola (n = 9). Genomes of 11 isolates could be closed, allowing the elucidation of the genetic contexts of the carbapenemase genes. The blaGES-5 gene was located within a class 1 integron, In2071 (cassette array, blaGES-5-aacA3-aadA16), on a 33 kb IncP6 plasmid. The blaFRI-8 genes were carried on IncFII(Yp) plasmids ranging in size from 191 kb to 244 kb, and the blaFRI-11 genes were carried on 70 kb and 74 kb IncFII(pECLA)/IncR plasmids. The blaIMI-22 and blaIMI-23 genes were co-located on a 107 kb plasmid. The blaSFC and blaSFH-1 genes were found on putative genomic islands inserted at tRNA-Phe genes in chromosomes.
This study revealed the presence of rare/novel carbapenemases among CPE in aquatic environments, suggesting that the environment may act as a potential reservoir of these minor carbapenemases.
产碳青霉烯酶肠杆菌目细菌（CPE）对公众健康构成严重威胁。与临床CPE相比，环境CPE的遗传特征尚不清楚。本研究旨在对从日本环境水体中分离出的CPE的碳青霉烯耐药基因决定因素进行表征。
从日本的河流和湖泊中采集了85份水样。使用选择性培养基鉴定CPE，并对获得的分离株（n = 21）进行全基因组测序。
鉴定出了多种罕见/新型碳青霉烯酶：植生拉乌尔菌中的GES-5（n = 1）、肠杆菌属中的FRI-8和FRI-11（n = 8）、解脲沙雷菌中的IMI-22和IMI-23（n = 3）以及丰蒂沙雷菌中的SFC-1、SFC-2和SFH-1（n = 9）。11株分离株的基因组可以完成拼接，从而阐明碳青霉烯酶基因的遗传背景。blaGES-5基因位于一个1类整合子In2071（盒式阵列，blaGES-5-aacA3-aadA16）内，位于一个33 kb的IncP6质粒上。blaFRI-8基因携带在大小从191 kb到244 kb的IncFII(Yp)质粒上，blaFRI-11基因携带在70 kb和74 kb的IncFII(pECLA)/IncR质粒上。blaIMI-22和blaIMI-23基因共位于一个107 kb的质粒上。blaSFC和blaSFH-1基因位于染色体上插入tRNA-Phe基因的假定基因组岛上。
本研究揭示了水生环境中CPE中存在罕见/新型碳青霉烯酶，表明环境可能是这些次要碳青霉烯酶的潜在储存库。
