Characterization of mobile genetic elements carrying VIM-1 and KPC-2 carbapenemases in Citrobacter freundii isolates in Madrid.

Carbapenemase producing Citrobacter freundii (CPCF) infections are still uncommon in European countries. Here we report a molecular study conducted in a tertiary care facility in southern Madrid, Spain, from 2009 to 2014 to investigate the epidemiology of CPCF. The bla IMP-1, bla IMP-2, bla KPC, bla NDM, bla OXA-48, bla VIM-1 and bla VIM-2 genes were screened by PCR. Molecular typing was carried out by Pulsed-field gel electrophoresis analysis (PFGE) and multilocus sequence typing (MLST). Whole genome sequencing (WGS) was performed to characterize the resistome and the mobile genetic elements associated with the carbapenems resistance of CPCF. A total of 11/521 (2.1%) isolates had reduced susceptibility to carbapenems. PCR amplification revealed the presence of bla VIM-1 in 10 isolates and bla KPC-2 in 2 isolates. One C. freundii isolate co-harbored bla VIM-1 and bla KPC-2 genes. PFGE and MLST assigned 10 different clonal, 4 previously reported (ST11, ST18, ST22 and ST64) and 6 new STs (ST89, ST90, ST91, ST92, ST92 and ST94). The bla VIM-1 gene was part of In624 ( intI1-bla VIM-1 - aacA4 - dfrB1-aadA1 - catB2 - qacEΔ1 / sul1 ). In 3 of these isolates, plasmid-mediated quinolone resistance genes ( qnrA1 and qnrB4 ) were present in its downstream region, taking part of a complex class 1 integron ([In624:ISCR1: qnrB4 - bla DHA-1 ] and [In624:ISCR1: qnrA1 ]). On the other hand, the bla KPC-2 gene was associated with a Tn3-based transposon. The dissemination of the bla VIM-1 gene among various clones suggests a successful horizontal transfer of integron carrying elements that play a dominant role in the development of multidrug resistance in Enterobacteriaceae . [ABSTRACT FROM AUTHOR]