Ongoing epidemic of blaVIM-1-positive Klebsiella pneumoniae in Athens, Greece: a prospective survey.
OBJECTIVE
To determine the current frequency and study the characteristics of VIM-1-producing Klebsiella pneumoniae isolates from bloodstream infections in Greek hospitals.


METHODS
All blood isolates of K. pneumoniae were prospectively collected during 2004-06 in three teaching hospitals located in Athens. MICs of antibiotics were determined by the Etest. Extended-spectrum- (ESBL) and metallo-beta-lactamase (MBL) production was examined by clavulanate- and EDTA-based techniques, respectively. Isolates were typed by PFGE of XbaI-digested genomic DNA. Detection of bla(VIM-1) and mapping of the VIM-1-encoding integrons were performed by PCR and sequencing. Beta-lactamase activities were analysed by IEF and imipenem hydrolysis was assessed by spectrophotometry. VIM-1-encoding plasmids were transferred to Escherichia coli by conjugation and transformation and characterized by Inc/rep typing and RFLP.


RESULTS
Sixty-seven (37.6%) of 178 K. pneumoniae blood isolates were bla(VIM-1)-positive (VPKP); 77.8% of these were from ICUs. All VPKP isolates were multidrug-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, 67.2%) as indicated by resistance to aztreonam and confirmed by a clavulanate-based double-disc synergy test. The responsible ESBL was always an SHV-5-type enzyme as indicated by IEF. PFGE identified eight clusters (A-H) 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. Location of bla(VIM-1) and expression of VIM-1 were studied in 12 isolates representing the eight PFGE clusters. In all isolates, bla(VIM-1) was part of a class 1 integron that also carried aacA4, dhfrI, aadA and sulI. In eight isolates (clusters C, D, G and H), the bla(VIM-1) integron was located in transferable IncN plasmids. A cluster F isolate carried a VIM-1-encoding, self-transferable plasmid that was not typeable by Inc/rep typing. VIM-1-encodingreplicons were not identified in three isolates (PFGE clusters A, B and E). VPKP isolates exhibited differences in imipenem-hydrolysing activities which, however, were not correlated with the respective carbapenem MICs.


CONCLUSIONS
A multiclonal epidemic of bla(VIM-1)-carrying K. pneumoniae is under way in the majorhospitals in Greece. Microorganisms producing both VIM-1 and SHV-5 constitute the prevalent multidrug-resistant population of K. pneumoniae in this setting.
Psichogiou
M
M
First Department of Propaedeutic Medicine, Medical School, University of Athens, Athens, Greece.
Tassios
P T
PT
Avlamis
A
A
Stefanou
I
I
Kosmidis
C
C
Platsouka
E
E
Paniara
O
O
Xanthaki
A
A
Toutouza
M
M
Daikos
G L
GL
Tzouvelekis
L S
LS
D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D015780:Carbapenems / Q000494:pharmacology / Q000627:therapeutic use*; D003428:Cross Infection / Q000201:enzymology / Q000453:epidemiology* / Q000382:microbiology; D004196:Disease Outbreaks; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D006115:Greece / Q000453:epidemiology; D006801:Humans; D007710:Klebsiella Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D011446:Prospective Studies; D001618:beta-Lactamases / Q000096:biosynthesis / Q000235:genetics
D000900:Anti-Bacterial Agents; D015780:Carbapenems; C417264:VIM-1 metallo-beta-lactamase; D001618:beta-Lactamases