title: A possible alternative to the error prone modified Hodge test to correctly identify the carbapenemase producing Gram-negative bacteria.
abstract: BACKGROUND
  The modified Hodge test (MHT) is widely used as a screening test for the detection of carbapenemases in Gram-negative bacteria. This test has several pitfalls in terms of validity and interpretation. Also the test has a very low sensitivity in detecting the New Delhi metallo-β-lactamase (NDM). Considering the degree of dissemination of the NDM and the growing pandemic of carbapenem resistance, a more accurate alternative test is needed at the earliest.
  
  
  OBJECTIVE
  The study intends to compare the performance of the MHT with the commercially available Neo-Sensitabs - Carbapenemases/Metallo-β-Lactamase (MBL) Confirmative Identification pack to find out whether the latter could be an efficient alternative to the former.
  
  
  METHODS
  A total of 105 isolates of Klebsiella pneumoniae resistant to imipenem and meropenem, collected prospectively over a period of 2 years were included in the study.
  
  
  METHODS
  The study isolates were tested with the MHT, the Neo-Sensitabs - Carbapenemases/MBL Confirmative Identification pack and polymerase chain reaction (PCR) for detecting the blaNDM-1 gene.
  
  
  RESULTS
  Among the 105 isolates, the MHT identified 100 isolates as carbapenemase producers. In the five isolates negative for the MHT, four were found to produce MBLs by the Neo-Sensitabs. The Neo-Sensitabs did not have any false negatives when compared against the PCR.
  
  
  CONCLUSIONS
  The MHT can give false negative results, which lead to failure in detecting the carbapenemase producers. Also considering the other pitfalls of the MHT, the Neo-Sensitabs--Carbapenemases/MBL Confirmative Identification pack could be a more efficient alternative for detection of carbapenemase production in Gram-negative bacteria.
authors.forename: S S
authors.initials: SS
authors.lastname: Jeremiah
authors.affiliation: Department of Microbiology, Christian Medical College, Vellore, Tamil Nadu, India.
authors.forename: V
authors.initials: V
authors.lastname: Balaji
authors.forename: S
authors.initials: S
authors.lastname: Anandan
authors.forename: R D
authors.initials: RD
authors.lastname: Sahni
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis*; D001431:Bacteriological Techniques / Q000379:methods*; D005188:False Negative Reactions; D006801:Humans; D007711:Klebsiella pneumoniae / Q000201:enzymology*; D008403:Mass Screening / Q000379:methods; D012680:Sensitivity and Specificity; D001618:beta-Lactamases / Q000032:analysis*
chemical_list: D001426:Bacterial Proteins; D001618:beta-Lactamases; C063912:carbapenemase