Department of Microbiology, University of Hong Kong, Pokfulam, Hong Kong, China.
J Appl Microbiol. 2013 Mar;114(3):695-702. doi: 10.1111/jam.12099. Epub 2012 Dec 27.
To investigate plasmid-mediated fosfomycin resistance related to fosA3 in Escherichia coli isolates collected from different animals in Hong Kong, China, 2008-2010.
In total, 2106 faecal specimens from 210 cattle, 214 pigs, 460 chickens, 398 stray cats, 368 stray dogs and 456 wild rodents were cultured. The faecal colonization rates of fosfomycin-resistant E. coli were as follows: 11.2% in pigs, 8.6% in cattle, 7.3% in chickens, 2.4% in dogs, 0.8% in cats and 1.5% in rodents. The cultures yielded 1693 isolates of which 831 were extended-spectrum β-lactamases (ESBL) producers. Fosfomycin-resistant isolates were more likely than fosfomycin-susceptible isolates to be producers of ESBL and to have resistance to chloramphenicol, ciprofloxacin, cotrimoxazole, gentamicin and tetracycline. Of the 101 fosfomycin-resistant isolates, 97 (96.0%) isolates were fosA3 positive and 94 (93.1%) were bla(CTX) (-M) positive. PCR mapping showed that the fosA3-containing regions were flanked by IS26, both upstream and downstream in 81 (83.5%) isolates, and by an upstream bla(CTX-M-14) -containing transposon-like structure (ΔISEcp1-bla(CTX-M-14) -ΔIS903 or ISEcp1-IS10 -bla(CTX-M-14) -ΔIS903) and a downstream IS26 in 14 (14.4%) isolates. For the remaining two isolates, fosA3 was flanked by a downstream IS26 but the upstream part cannot be defined. In a random subset of 18 isolates, fosA3 was carried on transferable plasmids with sizes of 50-200 kb and the following replicons: F2:A-B- (n = 3), F16:A1:B- (n = 2), F24:A-B- (n = 1), N (n = 1), B/O (n = 1) and untypeable (n = 3).
This study demonstrates the emergence of fosA3-mediated fosfomycin resistance among multidrug-resistant E. coli isolates from various animals. IS26 transposon-like structures might be the main vehicles for dissemination of fosA3.
研究 2008-2010 年期间中国香港地区从不同动物中分离出的大肠埃希菌中与 fosA3 相关的质粒介导的磷霉素耐药性。
共培养了 2106 份来自 210 头奶牛、214 头猪、460 只鸡、398 只流浪猫、368 只流浪狗和 456 只野生啮齿动物的粪便标本。磷霉素耐药大肠埃希菌的粪便定植率分别为：猪 11.2%、牛 8.6%、鸡 7.3%、狗 2.4%、猫 0.8%、鼠 1.5%。培养物共产生 1693 株分离株，其中 831 株为产超广谱β-内酰胺酶（ESBL）的菌株。与磷霉素敏感分离株相比，磷霉素耐药分离株更有可能产生 ESBL，且对氯霉素、环丙沙星、复方新诺明、庆大霉素和四环素耐药。在 101 株磷霉素耐药分离株中，97 株（96.0%）分离株 fosA3 阳性，94 株（93.1%） bla(CTX)-M 阳性。PCR 图谱显示，fosA3 所在区域上下游均被 IS26 侧翼，81 株（83.5%）分离株为上游 bla(CTX-M-14) 携带转座子样结构（ΔISEcp1-bla(CTX-M-14)-ΔIS903 或 ISEcp1-IS10-bla(CTX-M-14)-ΔIS903）和下游 IS26，14 株（14.4%）分离株为下游 IS26 侧翼，但上游部分无法确定。对于其余 2 株分离株，fosA3 被下游 IS26 侧翼，但上游部分无法确定。在随机选择的 18 株分离株中，fosA3 携带 50-200 kb 的可转移质粒，其复制子为：F2:A-B-（n = 3）、F16:A1:B-（n = 2）、F24:A-B-（n = 1）、N（n = 1）、B/O（n = 1）和未定型（n = 3）。
本研究表明，多种动物来源的多重耐药大肠埃希菌中出现了 fosA3 介导的磷霉素耐药性。IS26 转座子样结构可能是 fosA3 传播的主要载体。
