Φαινοτυπικά και γενετικά χαρακτηριστικά στελεχών Klebsiella pneumoniae MBL - θετικών

Background: Previous reports have establisted the occurence of sporadic cases blaVIM-1-carrying K. pneumoniae isolates in our country. The present study had to determine the current frequency of VPKP isolates in three hospitals in Athens, to study the fhenotypic and genotypic characteristics of these isolates and to evaluate the detecting methods of MBL-producing K. pneumoniae. Materials and methods: A prospective study was conducted during 2004-2006 in three teaching hospitals located in Athens when all blood isolates of K. pneumoniae where collected. MICs of antibiotics were determined by the Etest. Extendedspectrum-( ESBL) and metallo-β-lactamase (MBL) production was examined by clavulanate- and EDTA-based techniques, respectively. Detection of blaVIM genes and mapping of the VIM-encoding integrons were performed by PCR and sequencing. Isolates were typed by pulsed field gel electrophoresis (PFGE) of XbaIdigested genomic DNA. Results: Sixty-seven (37.6%) of 178 K. pneumoniae blood isolates were blaVIM-1 - positive (VPKP); 77.8% of these were from ICUs. In all isolates, blaVIM-1 was located in a class 1 integron that also carried ααcA4, dhfrI, ααdA and sulI. All VPKP isolates were multi-drug resistant. The MICs of carbapenems for VPKP varied from the susceptible range to high-level resistance overlapping with those of MBL-negative isolates. The EDTA-imipenem synergy methods had reduced sensitivity in detecting VPKP isolates when the MICs were in the susceptible range. ESBL production was common among VPKP isolates (n=45) as indicated by resistance to aztreonam and confirmed by a clavulanate-based double disc synergy test. PFGE identified eight clusters of VPKP isolates with related (>80%) patterns, as well as four unique types. Both inter-hospital spread of several clones and genotypic similarities among susceptible, ESBL-positive and VPKP isolates were also observed. Conclusion: A multi-clonal epidemic of blaVIM-1-carrying K. pneumoniae has been detected in three major hospitals in Greece. Microorganisms ...