Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada R3E 0J9.
J Antimicrob Chemother. 2013 May;68 Suppl 1:i57-65. doi: 10.1093/jac/dkt027.
To assess the proportion of Escherichia coli and Klebsiella pneumoniae from Canadian hospitals that produce extended-spectrum β-lactamases (ESBLs), AmpC β-lactamases and carbapenemases, as well as to describe the patterns of antibiotic resistance and molecular characteristics of these organisms.
Some 5451 E. coli and 1659 K. pneumoniae were collected from 2007 to 2011 inclusive as part of the ongoing CANWARD national surveillance study. Antimicrobial susceptibility testing was performed to detect putative ESBL, AmpC and carbapenemase producers, which were then further characterized by PCR and sequencing to detect resistance genes. In addition, isolates were characterized by PFGE and an allele-specific PCR to detect isolates of sequence type (ST) 131.
The proportion of ESBL-producing E. coli (2007, 3.4%; 2011, 7.1%), AmpC-producing E. coli (2007, 0.7%; 2011, 2.9%) and ESBL-producing K. pneumoniae (2007, 1.5%; 2011, 4.0%) among the isolates collected increased during the study period. The majority of ESBL-producing E. coli (>95%), AmpC-producing E. coli (>97%) and ESBL-producing K. pneumoniae (>89%) remained susceptible to colistin, amikacin, ertapenem and meropenem. Isolates were generally unrelated by PFGE (<80% similarity); however, ST131 was identified among 55.8% and 28.7% (P < 0.001) of ESBL- and AmpC-producing E. coli, respectively. CTX-M-15 was the dominant genotype in both ESBL-producing E. coli (66.2%) and ESBL-producing K. pneumoniae (50.0%), while the dominant genotype in AmpC-producing E. coli was CMY-2 (55.7%). Carbapenemase production was identified in 0.04% (n = 2) of E. coli and 0.06% (n = 1) of K. pneumoniae, all of which produced KPC-3.
The proportion of ESBL- and AmpC-producing E. coli and K. pneumoniae increased significantly during the study period, while the number of carbapenemase producers remained low (<1%). Compared with AmpC-producing E. coli, ESBL-producing E. coli were significantly associated with multidrug resistance and the ST131 clone.
评估加拿大医院产生超广谱β-内酰胺酶（ESBLs）、AmpC β-内酰胺酶和碳青霉烯酶的大肠埃希菌和肺炎克雷伯菌的比例，并描述这些细菌的抗生素耐药模式和分子特征。
作为正在进行的加拿大国家监测研究的一部分，在 2007 年至 2011 年期间共收集了 5451 株大肠埃希菌和 1659 株肺炎克雷伯菌。进行了抗生素敏感性试验，以检测推定的 ESBL、AmpC 和碳青霉烯酶产生菌，然后通过 PCR 和测序进一步鉴定耐药基因。此外，通过 PFGE 和等位基因特异性 PCR 对分离株进行了特征分析，以检测序列型（ST）131 的分离株。
在研究期间，分离株中 ESBL 产大肠埃希菌（2007 年，3.4%；2011 年，7.1%）、AmpC 产大肠埃希菌（2007 年，0.7%；2011 年，2.9%）和 ESBL 产肺炎克雷伯菌（2007 年，1.5%；2011 年，4.0%）的比例有所增加。大多数 ESBL 产大肠埃希菌（>95%）、AmpC 产大肠埃希菌（>97%）和 ESBL 产肺炎克雷伯菌（>89%）对黏菌素、阿米卡星、厄他培南和美罗培南仍敏感。通过 PFGE（<80%相似度），分离株通常没有相关性；然而，在 ESBL 产大肠埃希菌和 AmpC 产大肠埃希菌中分别有 55.8%和 28.7%（P<0.001）的分离株为 ST131。CTX-M-15 是 ESBL 产大肠埃希菌（66.2%）和 ESBL 产肺炎克雷伯菌（50.0%）中的主要基因型，而 AmpC 产大肠埃希菌中的主要基因型为 CMY-2（55.7%）。在 0.04%（n=2）的大肠埃希菌和 0.06%（n=1）的肺炎克雷伯菌中鉴定出了碳青霉烯酶产生菌，它们都产生了 KPC-3。
在研究期间，ESBL 和 AmpC 产大肠埃希菌和肺炎克雷伯菌的比例显著增加，而碳青霉烯酶产生菌的数量仍然很低（<1%）。与 AmpC 产大肠埃希菌相比，ESBL 产大肠埃希菌与多药耐药和 ST131 克隆显著相关。
