AUTHOR=Wang Xuan , Chen Gongxiang , Wu Xiaoyan , Wang Liangping , Cai Jiachang , Chan Edward W. , Chen Sheng , Zhang Rong 

TITLE=Increased prevalence of carbapenem resistant Enterobacteriaceae in hospital setting due to cross-species transmission of the blaNDM-1 element and clonal spread of progenitor resistant strains

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.00595

DOI=10.3389/fmicb.2015.00595

ISSN=1664-302X

ABSTRACT=<p>This study investigated the transmission characteristics of carbapenem-resistant <italic>Enterobacteriaceae</italic> (CRE) strains collected from a hospital setting in China, in which consistent emergence of CRE strains were observable during the period of May 2013 to February 2014. Among the 45 CRE isolates tested, 21 (47%) strains were found to harbor the <italic>bla</italic><sub>NDM-1</sub> element, and the rest of 24 CRE strains were all positive for <italic>bla</italic><sub>KPC-2</sub>. The 21 <italic>bla</italic><sub>NDM-1</sub>—borne strains were found to comprise multiple <italic>Enterobacteriaceae</italic> species including nine <italic>Enterobacter cloacae</italic>, three <italic>Escherichia coli</italic>, three <italic>Citrobacter freundii</italic>, two <italic>Klebsiella pneumoniae</italic>, two <italic>Klebsiella oxytoca</italic>, and two <italic>Morganella morganii</italic> strains, indicating that cross-species transmission of <italic>bla</italic><sub>NDM-1</sub> is a common event. Genetic analyses by PFGE and MLST showed that, with the exception of <italic>E. coli</italic> and <italic>E. cloacae</italic>, strains belonging to the same species were often genetically unrelated. In addition to <italic>bla</italic><sub>NDM-1</sub>, several CRE strains were also found to harbor the <italic>bla</italic><sub>KPC-2</sub>, <italic>bla</italic><sub>VIM-1</sub>, and <italic>bla</italic><sub>IMP-4</sub> elements. Conjugations experiments confirmed that the majority of carbapenem resistance determinants were transferable. Taken together, our findings suggest that transmission of mobile resistance elements among members of <italic>Enterobacteriaceae</italic> and clonal spread of CRE strains may contribute synergistically to a rapid increase in the population of CRE in clinical settings, prompting a need to implement more rigorous infection control measures to arrest such vicious transmission cycle in CRE-prevalent areas.</p>