National Microbiology Laboratory, Winnipeg, Canada.
J Antimicrob Chemother. 2011 Jun;66(6):1273-7. doi: 10.1093/jac/dkr092. Epub 2011 Mar 15.
This study examined Klebsiella pneumoniae clinical isolates and their bla(KPC) plasmids to determine potential relatedness of the isolates and their plasmids harbouring carbapenem resistance mechanisms.
K. pneumoniae carbapenemase (KPC)-producing K. pneumoniae from New York City (NYC) (n = 19) and Toronto (n = 2) were typed by PFGE and multilocus sequence typing (MLST). bla(KPC)-harbouring plasmids were transformed into Escherichia coli DH10B(TM), restricted using EcoRI and analysed for bla content and replicon (rep) type. Susceptibility profiles for clinical and transformed strains were determined by automated microbroth dilution using CLSI breakpoints. Outer membrane protein (OMP) genes were analysed by sequencing of ompk35 and ompk36.
PFGE analysis identified 17 related strains (≥ 80% similarity; 11 KPC-2, 6 KPC-3) where ST258 was the dominant clonal type. All clinical isolates contained both bla(SHV) and bla(TEM-1) and, with the exception of one isolate, were multidrug resistant (MDR). Transformed KPC plasmids (n = 21) carried TEM-1 (n = 18) and were MDR (n = 5). Three plasmid clusters, repFIIA (n = 10), repR (n = 3) and an unknown type (n = 3), were observed. repFllA plasmids were observed from both NYC and Toronto strains. OMP gene analysis revealed premature stop codons in ompk35 and numerous deletions and insertions in ompk36.
The dissemination of bla(KPC) is due both to carriage of similar KPC-harbouring plasmids within genetically distinct K. pneumoniae and to clonal spread of K. pneumoniae with unrelated KPC plasmids.
本研究对来自纽约市（NYC）（n=19）和多伦多（n=2）的产肺炎克雷伯菌碳青霉烯酶（KPC）肺炎克雷伯菌临床分离株及其携带碳青霉烯类耐药机制的 bla（KPC）质粒进行检测，以确定这些分离株及其质粒之间的潜在关联性。
对来自纽约市（NYC）（n=19）和多伦多（n=2）的产肺炎克雷伯菌碳青霉烯酶（KPC）肺炎克雷伯菌进行 PFGE 和多位点序列分型（MLST）分型。将 bla（KPC）携带质粒转化入大肠杆菌 DH10B（TM），用 EcoRI 限制，分析 bla 含量和复制子（rep）类型。采用 CLSI 折点的自动化微孔稀释法测定临床和转化株的药敏谱。通过 ompk35 和 ompk36 的测序分析外膜蛋白（OMP）基因。
PFGE 分析鉴定出 17 株相关菌株（≥80%相似度；11 株 KPC-2，6 株 KPC-3），其中 ST258 为优势克隆类型。所有临床分离株均同时携带 bla（SHV）和 bla（TEM-1），除 1 株外均为多重耐药（MDR）。转化的 KPC 质粒（n=21）携带 TEM-1（n=18）且为 MDR（n=5）。观察到 3 种质粒簇，分别为 repFIIA（n=10）、repR（n=3）和未知类型（n=3）。来自纽约市和多伦多菌株的均观察到 repFllA 质粒。OMP 基因分析显示 ompk35 存在提前终止密码子，ompk36 存在大量缺失和插入。
bla（KPC）的传播既归因于具有不同遗传背景的肺炎克雷伯菌携带相似的 bla（KPC）携带质粒，也归因于不相关的 KPC 质粒在肺炎克雷伯菌中的克隆传播。
