Multiclonal spread of VIM-1-producing Enterobacter cloacae isolates associated with In624 and In488 integrons located in an IncHI2 plasmid.
Over a 6-year period (2007-2012), the emergence of Enterobacter cloacae isolates resistant to β-lactams and with reduced susceptibility to carbapenems was observed in Hospital Universitario 12 de Octubre (Madrid, Spain). To determine the possible role of metallo-β-lactamases (MBLs) in the resistance profile of these isolates, a molecular and clinical epidemiological study was performed, including determination of patients' clinical characteristics, genetic diversity of strains, resistance mechanisms to carbapenems, and the genetic environment of VIM-1. A total of 73 E. cloacae isolates showed resistance to extended-spectrum cephalosporins and reduced susceptibility to at least one carbapenem during 2007-2012. PCR amplification revealed the presence of bla(VIM-1) gene in 37 isolates, bla(VIM-2) in 1 isolate and bla(KPC) in 5 isolates. Molecular typing showed high clonal diversity of E. cloacae isolates carrying bla(VIM-1). The genetic environment of bla(VIM-1) was investigated and two integron structures were found: intI-bla(VIM-1)-aacA4-dfrB1-aadA1-catB2-qacEΔ1/sul1 (In624); and intI-bla(VIM-1)-aacA4-aadA1-qacEΔ1/sul1 (In488). Isolates belonging to three clones (A, F and G) harboured different types of integron (In624 or In488) despite belonging to the same clone. Conjugal experiments showed an association with a conjugative plasmid of ca. 300 kb belonging to IncHI2 group, which is common in Spanish hospitals, suggesting that the widespread dissemination of bla(VIM-1) may be due to horizontal transfer of mobile genetic determinants rather than the result of spreading of a few clones. These results have implications for infection control programmes in the hospital.
Servicio de Microbiología Clínica, Hospital Universitario 12 de Octubre, Avenida de Córdoba sn, Madrid 28041, Spain.
Jennifer
J
Villa
Servicio de Microbiología Clínica, Hospital Universitario 12 de Octubre, Avenida de Córdoba sn, Madrid 28041, Spain.
Esther
E
Viedma
Servicio de Microbiología Clínica, Hospital Universitario 12 de Octubre, Avenida de Córdoba sn, Madrid 28041, Spain.
Patricia
P
Brañas
Servicio de Microbiología Clínica, Hospital Universitario 12 de Octubre, Avenida de Córdoba sn, Madrid 28041, Spain.
M Angeles
MA
Orellana
Servicio de Microbiología Clínica, Hospital Universitario 12 de Octubre, Avenida de Córdoba sn, Madrid 28041, Spain.
Joaquín R
JR
Otero
Servicio de Microbiología Clínica, Hospital Universitario 12 de Octubre, Avenida de Córdoba sn, Madrid 28041, Spain. Electronic address: fernando.chaves@salud.madrid.org.
Fernando
F
Chaves
D000328:Adult; D000368:Aged; D016000:Cluster Analysis; D016972:Enterobacter cloacae / Q000145:classification* / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000453:epidemiology* / Q000382:microbiology; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D032023:Integrons; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D058889:Molecular Typing; D010957:Plasmids; D016133:Polymerase Chain Reaction; D012189:Retrospective Studies; D013030:Spain / Q000453:epidemiology; D001618:beta-Lactamases / Q000378:metabolism
C417264:VIM-1 metallo-beta-lactamase; D001618:beta-Lactamases
Enterobacter cloacae; IncHI2 plasmid; Integron; VIM-1