title: NDM-1 (New Delhi metallo beta lactamase-1) producing Gram-negative bacilli: emergence & clinical implications.
abstract: BACKGOUND & OBJECTIVES: Resistance to carbapenems in Gram-negative bacteria conferred by NDM-1 is a global health problem. We investigated the occurrence of NDM-1 in clinical isolates of Gram-negative bacilli in a tertiary care hospital in Kashmir valley, India.
  
  
  METHODS
  Gram-negative bacilli from different clinical isolates were included in the study. Antimicrobial susceptibility was performed by Kirby Bauer disk diffusion method and interpreted using Clinical Laboratory Standards Institute (CLSI) guidelines. Isolates resistant to carbapenems were subjected to different phenotypic test such as modified Hodge test (MHT), boronic acid and oxacillin based MHT ( BA-MHT and OXA-MHT), combined disk test and minimum inhibitory concentration (MIC) with imipenem and imipenem -EDTA for determination of class B metallo enzymes. Presence of blaNDM-1 gene was established by PCR and confirmed by sequencing.
  
  
  RESULTS
  Of the total 1625 Gram-negative isolates received, 100 were resistant to imipenem. Of the 100 isolates, 55 (55%) were positive by modified Hodge test indicating carbapenemase production. Of the 100 isolates tested by MHT, BA-MHT and OXA-MHT, 29 (29%) isolates belonged to Class A and 15 (15%) to Class B, while 56 (56%) isolates were negative. Of the 15 class B metallo beta lactamase producers, nine carried the bla(NDM-1) gene. NDM-1 was found among Escherichia coli (2 isolates), Klebsiella pneumoniae (2 isolates), Citrobacter freundii (3 isolates), Acinetobacter spp (1 isolate), and one isolate of Pseudomonas aeruginosa. Isolates were resistant to all antibiotic tested except polymyxin B and tigecycline.
  
  
  CONCLUSIONS
  Our study showed the presence of clinical isolates expressing NDM-1 in Srinagar, Jammu & Kashmir, India. These isolates harbour plasmid mediated multiple drug resistant determinants and can disseminate easily across several unrelated genera. To halt their spread, early identification of these isolates is mandatory.
authors.affiliation: Department of Microbiology, Sher-i-Kashmir Institute of Medical Sciences, Srinagar, Jammu & Kashmir, India.
authors.forename: Bashir Ahmad
authors.initials: BA
authors.lastname: Fomda
authors.forename: Asiya
authors.initials: A
authors.lastname: Khan
authors.forename: Danish
authors.initials: D
authors.lastname: Zahoor
mesh_terms: D000150:Acinetobacter / Q000187:drug effects / Q000201:enzymology; D015780:Carbapenems / Q000494:pharmacology*; D016971:Citrobacter freundii / Q000187:drug effects / Q000201:enzymology; D052978:Disk Diffusion Antimicrobial Tests; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D006801:Humans; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology; D008826:Microbial Sensitivity Tests; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000201:enzymology; D062606:Tertiary Care Centers; D001618:beta-Lactamases / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D015780:Carbapenems; D001618:beta-Lactamases; C552864:beta-lactamase NDM-1