Molecular Characterization of Class 1 Integrons and Carbapenem-Resistant Genes in Enterobacter cloacae Complex...

Enterobacter cloacae complex (ECC) widely exists in the hospital environment and is one of the important conditional pathogens of hospital-acquired infection. To investigate the distribution of integrons and carbapenem-resistant genes in clinical ECC, 70 isolates of ECC from non-sputum specimens were collected. Class 1 and class 2 integron integrase gene intI1 and intI2, as well as common carbapenem-resistant genes, bla_KPC, bla_VIM, bla_IMP, bla_NDM, bla_GES, and bla_OXA-23, were screened. Gene cassette arrays and common promoters of class 1 integron together with subtypes of carbapenem-resistant genes were determined by sequencing. Resistant rates to commonly used antimicrobial agents between class 1 integron-positive and integron-negative ECC isolates were analyzed. The whole-genome of bla_NDM-7 harboring Enterobacter hormaechei was sequenced and the sequence around bla_NDM-7 was analyzed. Twenty isolates were positive for intI1. Nineteen different antimicrobial-resistant gene cassettes and 11 different gene cassette arrays, including aadA22-lnuF, were detected in this study. Common promoters of class 1 integron PcH1, PcW, PcW-P2, and PcH2 were detected in 12, 4, 3, and 1 isolates, respectively. The rates of antimicrobial resistance of intI1-positive isolates were higher than those of intI1-negative isolates to clinical commonly used antimicrobial agents. Carbapenem-resistant genes bla_KPC-2, bla_NDM-1, bla_NDM-2, and bla_NDM-7 were detected in 2, 1, 1, and 1 isolates, respectively. bla_NDM-7 was located between ble_MBL and IS5. To the best of our knowledge, this study reported for the first time of bla_NDM-7 in ECC isolate in China.