Novel class 1 Integrons and sequence types in VIM-2 and VIM-11-producing clinical strains of Enterobacter cloacae

Abstract All VIM-producing Enterobacteriaceae (six Enterobacter cloacae ) submitted to the Argentinian Reference Laboratory in Antimicrobial Resistance in the period 2008–13 were characterized. The isolates were referred from 6 nosocomial institutions located in 5 different cities across the country. All isolates showed carbapenem disk diffusion inhibition zones ≤ 22 mm and synergism between a carbapenem disk and EDTA/SMA. The six isolates were PCR positive for bla VIM . Imipenem MICs were ≤ 1 to 8 μg/ml. Typing by PFGE and MLST distinguished six pulsotypes and sequence types with bla VIM located on novel class 1 integron arrays: ECL-1: ST182, In 883 ; ECL-2, ST90, In 885; ECL-3, ST88, In 346 with bla VIM-11 ; ECL-4, ST184, In 900 ; ECL-5, ST749-new, In 900 ; ECL-6, ST 91 and uncharacterized In. Only ECL-2 was able to transfer bla VIM-2 to E. coli J53 by biparental conjugation. bla VIM was located in plasmids of 53–82 Kb and in the chromosome (ECL-1 and ECL-5). The diversity of clones, class 1 integrons, plasmids and location of bla VIM , reveals the plasticity of the genetic elements described and highlights the importance of surveillance programs as tools to identify the transmission of these highly resistant metallo-β-lactamase-producing Enterobacteriaceae .