title: Screening for New Delhi metallo-β-lactamase-1 in Enterobacteriaceae: Is there a role for the modified Hodge test?
abstract: OBJECTIVE
  The New Delhi metallo-β-lactamase-1 (NDM-1) enzyme is a plasmid-encoded enzyme that inactivates carbapenem antibiotics. This study aims to ascertain if the modified Hodge test (MHT) has a role in screening for NDM-1 in Enterobacteriaceae with reduced carbapenem susceptibility.
  
  
  METHODS
  Over a period of one year, all Enterobacteriaceae isolates from all clinical specimens with reduced susceptibility to at least one carbapenem were subjected to MHT and conventional polymerase chain reaction (PCR) detection of the NDM-1 gene.
  
  
  RESULTS
  A total of 13,098 Enterobacteriaceae isolates were screened and 63 (0.48%) had reduced susceptibility to at least one carbapenem. Out of the 63 isolates, 45 (71.4%) were MHT-positive. The NDM-1 gene was detected in 18 of the 63 isolates (28.6%). All 18 PCR-positive isolates were also MHT-positive. Thus, the sensitivity and specificity of the MHT in detecting NDM-1 in Enterobacteriaceae with reduced carbapenem susceptibility are 100% and 40%, respectively.
  
  
  CONCLUSIONS
  The MHT is a useful test to screen for the presence of NDM-1 in Enterobacteriaceae with reduced carbapenem susceptibility. However, due to its rather low specificity, all MHT-positive isolates should be subjected to alternative tests (e.g. PCR) for confirmation, especially if other types of carbapenemases (e.g. KPC) are prevalent.
authors: Nor Zanariah Zainol Abidin, Department of Medical Microbiology & Immunology, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia.
authors: Nor Zanariah Zainol
authors: NZ
authors: Abidin
authors: Anita Sulong, Department of Medical Microbiology & Immunology, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia.
authors: Anita
authors: A
authors: Sulong
authors: Hanafiah Alfizah, Department of Medical Microbiology & Immunology, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia.
authors: Hanafiah
authors: H
authors: Alfizah
authors: Chuan Hun Ding, Department of Medical Microbiology & Immunology, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia.
authors: Chuan Hun
authors: CH
authors: Ding
authors: Najihan Abdul Samat Muttaqillah, Department of Medical Microbiology & Immunology, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia.
authors: Najihan Abdul Samat
authors: NA
authors: Muttaqillah
authors: Md Mostafizur Rahman. Department of Medical Microbiology & Immunology, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia.
authors: Md Mostafizur
authors: MM
authors: Rahman
keywords: Enterobacteriaceae; MHT; NDM-1; metallo-β-lactamase-1; modified Hodge test