Infrequent detection of acquired metallo-beta-lactamases among carbapenem-resistant Pseudomonas isolates in a Greek hospital.
OBJECTIVE
To study the possible distribution of metallo-beta-lactamases among nosocomial Pseudomonas isolates in a Greek hospital with a recent high prevalence of carbapenem-resistant Pseudomonas isolates.


METHODS
All carbapenem-resistant (imipenem- and/or meropenem-resistant) (MICs > 8 mg/L) Pseudomonas non-replicate isolates recovered from clinical infections in the Microbiology Laboratory of Saint Demetrios Hospital, Thessaloniki, Greece, from April 1998 to November 2000 were studied for the presence of metallo-beta-lactamases. They were tested by a disk diffusion test, PCR analysis, and nucleotide sequencing. DNA fingerprints were obtained by pulsed-field gel electrophoresis (PFGE) of XbaI-digested chromosomal DNA.


RESULTS
In total, 24 carbapenem-resistant isolates (23 P. aeruginosa and one P. putida) were recovered. The serotypes observed among the P. aeruginosa isolates were, in order of decreasing frequency, O:11 (52%), O:3 and O:12 (17% each), and O:6 (13%). PFGE grouped 17 of the P. aeruginosa isolates into four clusters, each containing from two to seven isolates, while the remaining isolates exhibited unique genotypes. blaVIM-2 was detected in the P. putida isolate and a P. aeruginosa serotype O:3 isolate. The latter strain was genotypically distinct from other contemporaneous or older carbapenem-resistant P. aeruginosa Greek isolates.


CONCLUSIONS
These findings suggest that, although the prevalence of metallo-beta-lactamases is low, the integron-associated blaVIM genes can spread to P. aeruginosa serotypes that have not been previously associated with carbapenem resistance in our region, as well as to other pseudomonal species.
Tsakris
A
A
First Department of Microbiology, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece. atsakris@med.auth.gr
Tassios
P T
PT
Polydorou
F
F
Papa
A
A
Malaka
E
E
Antoniadis
A
A
Legakis
N J
NJ
D015780:Carbapenems / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D008826:Microbial Sensitivity Tests; D011549:Pseudomonas / Q000187:drug effects* / Q000201:enzymology*; D001618:beta-Lactamases / Q000032:analysis* / Q000235:genetics
D015780:Carbapenems; C425108:beta-lactamase bla(vim-2); D001618:beta-Lactamases