title: Detection and characterization of metallo beta lactamases producing Pseudomonas aeruginosa.
abstract: This study was undertaken to evaluate phenotypic and genotypic methods for detection of Metallo-Beta-Lactamases (MBLs) among nosocomial Pseudomonas aeruginosa. Sixty one among 176 P. aeruginosa isolates, collected as part of a multicentric study (2005-2007), were evaluated for carbapenem resistance (CARB-R; resistant to either imipenem/meropenem) and screened for MBL by Combination Disk Diffusion Test (CDDT) using imipenem (IMP), meropenem (MER) and ceftazidime (CAZ) with EDTA. MBL positives were further confirmed by IMP + EDTA Etest. Twenty strains (42.6%) were found to be MBL producers among the 61 P. aeruginosa. PCR for IMP and VIM MBL was performed on 48 of the 61, 15 were positive for VIM MBL type. CDDT using IMP + EDTA had the highest sensitivity and specificity of 87.8% and 84.4% when compared to Etest, which was higher than the values obtained for CAZ + EDTA and MER + EDTA. CDDT using IMP + EDTA also compared very well with the PCR (specificity = 90.9%, sensitivity = 93.3%). CARB-R among P. aeruginosa is mediated predominantly via MBL production. Clinical P. aeruginosa isolates can be screened routinely using the less expensive IMP + EDTA CDDT in clinical microbiology laboratories.
authors.affiliation: Department of Medicine, Unit I and Infectious Diseases, Benjamin M Pulimood Laboratories for Infection, Immunity and Inflammation, Christian Medical College, Vellore 632004, Tamil Nadu, India.
authors.forename: A
authors.initials: A
authors.lastname: Manoharan
authors.forename: S
authors.initials: S
authors.lastname: Chatterjee
authors.forename: D
authors.initials: D
authors.lastname: Mathai
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000032:analysis* / Q000235:genetics*; D003428:Cross Infection / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics; D006801:Humans; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction / Q000379:methods; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D012680:Sensitivity and Specificity; D001618:beta-Lactamases / Q000032:analysis* / Q000235:genetics*; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D047090:beta-Lactams; D001618:beta-Lactamases