Evaluation of imipenem/imipenem+EDTA disk method for detection of metallo-beta-lactamase-producing Klebsiella pneumoniae isolated from blood cultures.
The objective of this study was to evaluate the imipenem (IMP) and IMP+EDTA (IMP/IMP+EDTA) disk method for the detection of metallo-beta-lactamases (MBLs) in clinical isolates of Klebsiella pneumoniae with various MIC levels to IMP. Forty-one blood isolates of K. pneumoniae with MIC to IMP ranging from < or =0.5 to > or =16 microg/ml were examined. The MICs were determined by VITEK-2 (bioMerieux Vitek two, France). Disks of 10 microg IMP with and without the addition of 0.5 M EDTA were used for the IMP/IMP+EDTA disk method. The E-test (AB Biodisk, Solna, Sweden) for MBL detection was also used. All isolates were examined for the bla (VIM-1) gene by PCR and for clonality of VIM-1-producing isolates by pulsed-field gel electrophoresis (PFGE). All isolates with MIC values of IMP < or =0.5 microg/ml exhibited no differences in inhibition zone diameters (IZD) produced by IMP and IMP+EDTA disks, whereas the isolates with MICs > or =1 microg/ml showed an increase in IZD, ranging from 8 to 26 mm. All isolates with MIC values of > or =1 microg/ml were found positive for the bla (VIM-1) gene by PCR and for MBL production by the E-test, whereas none of isolates with MICs <0.5 microg/ml was found positive by any of the tests. DNA restriction fragments generated by PFGE of VIM-1-producing isolates were classified in four main types. The IMP/IMP+EDTA disk method is simple to perform, sensitive, and specific for detection of MBL-producing K. pneumoniae clinical isolates. K. pneumoniae isolates with MICs of IMP > or =1 microg/ml and/or IZD produced by IMP disk <19 mm should be tested for MBL production.
Petropoulou
Dimitra
D
Microbiology Department, G. Gennimatas General Hospital of Athens, GR-156 59 Athens, Greece.
Tzanetou
Konstantina
K
Syriopoulou
Vassiliki P
VP
Daikos
George L
GL
Ganteris
George
G
Malamou-Lada
Eleni
E
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016470:Bacteremia / Q000382:microbiology*; D004492:Edetic Acid / Q000494:pharmacology*; D006801:Humans; D015378:Imipenem / Q000494:pharmacology*; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000201:enzymology; D008826:Microbial Sensitivity Tests; D001618:beta-Lactamases / Q000096:biosynthesis / Q000235:genetics
D000900:Anti-Bacterial Agents; D015378:Imipenem; D004492:Edetic Acid; C417264:VIM-1 metallo-beta-lactamase; D001618:beta-Lactamases