Περίληψη:
The molecular epidemiology of VIM-producing Enterobacteriaceae isolated
at the beginning of an epidemic in the Intensive Care Unit (ICU) of a
university hospital in Athens, Greece, was studied. All Gram-negative
organisms isolated from March 2004 to November 2005 positive for
metallo-beta-lactamase (MBL) production were submitted to polymerase
chain reaction (PCR) and sequencing, to repetitive sequence-based PCR
(Rep-PCR) for molecular typing, and to S1 nuclease digestion for plasmid
DNA characterisation. Conjugation experiments and isoelectric focusing
were performed to identify co-existing beta-lactamases. Amongst 23
patients, 12 suffered one or more clinical infections. Eighty-two
isolates representing one isolate per clone, source and ICU patient were
studied, including Klebsiella pneumoniae (77), Enterobacter cloacae (2),
Citrobacter freundii (1) and Pseudomonas aeruginosa (2). High clonal
diversity was detected amongst the K. pneumoniae, with 10 distinct
clones identified. Conjugation was successful in 54.5% of K.
pneumoniae, and five different-sized plasmids were detected. All K.
pneumoniae and both E. cloacae isolates shared the same
bla(VIM-1)-containing class 1 integron structure also carrying aacA7,
dhfrI and aadA1 gene cassettes. The C. freundii isolate carried a
different integron that included bla(VIM-1) and aac(6’)-IIc. Both P.
aeruginosa isolates were positive for bla(VIM-2). It was not possible to
identify specific clones with the potential to cause clinical
infections. In conclusion, a multiclonal cluster of MBL-producers was
responsible for the first cases of colonisation and/or infection in the
ICU. A single integron structure, common in Greek hospitals, efficiently
disseminated between clones and species, suggesting that the epidemic
was mainly the result of successful horizontal transfer of mobile
genetic material rather than the result of horizontal transfer of one or
a few clones. (C) 2011 Elsevier B.V. and the International Society of
Chemotherapy. All rights reserved.
Συγγραφείς:
Koratzanis, Evangelos
Souli, Maria
Galani, Irene
Chryssouli,
Zoi
Armaganidis, Apostolos
Giamarellou, Helen
