title: Comparative Evaluation of Four Phenotypic Tests for Detection of Metallo-β-Lactamase and Carbapenemase Production in Acinetobacter baumannii.
abstract: BACKGROUND
  Acinetobacter baumannii is an emerging multi-drug resistant opportunistic pathogen that causes a variety of nosocomial infections. In recent years, carbapenem resistance in A.baumannii has increased due to Ambler class B Metallo β-lactamases or class D OXA Carbapenemases.
  
  
  OBJECTIVE
  The present study was undertaken to detect and compare the various phenotypic methods for MBL production in nosocomial A.baumannii isolates.
  
  
  METHODS
  One hundred sixty eight A.baumannii isolates were subjected to disc diffusion assay. Imipenem resistant isolates were subjected to 4 different phenotypic tests. MBL screening was done by Imipenem-EDTA double disc synergy test, Imipenem-EDTA combined disc test, Modified Hodge test and MBL E-test.
  
  
  RESULTS
  Out of 168 A.baumannii isolates, 85 (50.59%) were imipenem resistant. Among these 85 isolates, 57 (67.05%) were MBL positive by DDST, 69 (81.18%) by CDT, 85 (100%) by MHT and all these 85 isolates were confirmed to be MBL positive by MBL E-test method.
  
  
  CONCLUSIONS
  Combined disc test, Modified Hodge test & E-test are equally effective to detect MBL production. However, considering the cost constraints of E-test, simple MHT and CDT can be used. They are easy, economical and can be incorporated into routine testing in laboratories to monitor the emergence of MBLs in MDR A.baumannii.
authors.affiliation: Assisstant Professor, Department of Microbiology, Father Muller Medical College , Mangalore, Karnataka, India .
authors.forename: Aparna
authors.initials: A
authors.lastname: Shivaprasad
authors.affiliation: Professor, Department of Microbiology, Father Muller Medical College , Mangalore, Karnataka, India .
authors.forename: Beena
authors.initials: B
authors.lastname: Antony
authors.affiliation: Professor, Department of Microbiology, Father Muller Medical College , Mangalore, Karnataka, India .
authors.forename: Poornima
authors.initials: P
authors.lastname: Shenoy
keywords: Combined disc test (CDT); MBL E-test.; MDR Acinetobacter baumannii (MDR AB); Modified Hodge test (MHT)