title: Ertapenem disk performance to predict Klebsiella pneumoniae carbapenemase produced by Gram-negative bacilli isolated in a São Paulo city public hospital.
abstract: OBJECTIVE
  To evaluate ertapenem disk performance to predict Klebsiella pneumonie carbapenemase production by Gram-negative bacilli.
  
  
  METHODS
  All Gram-negative bacilli isolated between January 2010 and June 2011 were tested by disk diffusion (Oxoid™) for sensitivity to ertapenem, meropenem and imipenem. Resistant or intermediate sensitivity strains (diameter < 22 mm for ertapenem) were also tested for the blaKPC gene by polymerase chain reaction. Disk predictive positive value for Klebsiella pneumoniae carbapenemase and specificity were calculated.
  
  
  RESULTS
  Out of the 21839 cultures performed, 3010 (13.78%) were positive, and Gram-negative bacilli were isolated in 708 (23.52%) of them. Zone of inhibition diameter for ertapenem disk was < 22 mm for 111 isolates, representing 15.7% of all Gram-negative isolates. The PCR assay for blaKPC detected 40 Klebsiella pneumoniae carbapenemase-producing strains. No strains intermediate or resistant to meropenem and imipenem were sensitive to ertapenem. The ertapenem disk presented a positive predictive value of 36% to predict blaKPC and 89% specificity.
  
  
  CONCLUSIONS
  The resistance of Gram-negative bacilli detected by disk diffusion against ertapenem does not predict Klebsiella pneumoniae carbapenemase production. Other mechanisms, such as production of other betalactamases and porin loss, may be implicated. The need to confirm the presence of the blaKPC is suggested. Therefore, ertapenem was a weak predictor for discriminating strains that produce Klebsiella pneumoniae carbapenemase.
authors: Hospital Israelita Albert Einstein, São Paulo, SP, Brazil.
authors: Lais Pinto de
authors: LP
authors: Almeida
authors: Fabiana Puerro de
authors: FP
authors: Carvalho
authors: Alexandre Gimenes
authors: AG
authors: Marques
authors: Andrea dos Santos
authors: Ados S
authors: Pereira
authors: Renata Puzzo
authors: RP
authors: Bortoleto
authors: Marinês Dalla Valle
authors: MD
authors: Martino
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000032:analysis / Q000096:biosynthesis*; D001938:Brazil; D052978:Disk Diffusion Antimicrobial Tests / Q000379:methods*; D000077727:Ertapenem; D006090:Gram-Negative Bacteria / Q000302:isolation & purification; D006801:Humans; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology*; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000032:analysis / Q000096:biosynthesis*; D047090:beta-Lactams / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D047090:beta-Lactams; D001618:beta-Lactamases; C063912:carbapenemase; D000077727:Ertapenem