title: Comparative Evaluation of Multiplex PCR and Routine Laboratory Phenotypic Methods for Detection of Carbapenemases among Gram Negative Bacilli.
abstract: BACKGROUND
  Carbapenem resistant pathogens cause infections associated with significant morbidity and mortality.
  
  
  OBJECTIVE
  This study evaluates the use of Multiplex PCR for rapid detection of carbapenemase genes among carbapenem resistant Gram negative bacteria in comparison with the existing phenotypic methods like modified Hodge test (MHT), combined disc test (CDT) and automated methods.
  
  
  METHODS
  A total of 100 Carbapenem resistant clinical isolates, [Escherichia coli (25), Klebsiella pneumoniae (35) P. aeruginosa (18) and Acinetobacter baumannii (22)] were screened for the presence of carbapenemases (bla NDM-1, bla VIM , blaIMP and blaKPC genes) by phenotype methods such as the modified Hodge test (MHT) and combined disc test (CDT) and the molecular methods such as Multiplex PCR.
  
  
  RESULTS
  Seventy of the 100 isolates were MHT positive while, 65 isolates were positive by CDT. All the CDT positive isolates with EDTA and APB were Metallo betalactamase (MBL) and K. pneumoniae carbapenemase (KPC) producers respectively. bla NDM-1 was present as a lone gene in 44 isolates. In 14 isolates bla NDM-1 gene was present with blaKPC gene, and in one isolate bla NDM-1 gene was present with blaVIM , gene. Only one E. coli isolate had a lone blaKPC gene. We didn't find bla IMP gene in any of the isolates. Neither of the genes could be detected in 35 isolates.
  
  
  CONCLUSIONS
  Accurate detection of the genes related with carbapenemase production by Molecular methods like Multiplex PCR overcome the limitations of the phenotypic methods and Automated systems.
authors: Senior Resident, Department of Microbiology, Nizam's Institute of Medical Science , Panjagutta, Hyderabad, Telangana, India .
authors: Rachana
authors: R
authors: Solanki
authors: Research Scholar, Department of Microbiology, Nizam's Institute of Medical Science , Panjagutta, Hyderabad, Telangana, India .
authors: Lavanya
authors: L
authors: Vanjari
authors: Junoir Resident, Department of Microbiology, Nizam's Institute of Medical Science , Panjagutta, Hyderabad, Telangana, India .
authors: Sreevidya
authors: S
authors: Subramanian
authors: Technician, Department of Microbiology, Nizam's Institute of Medical Science , Panjagutta, Hyderabad, Telangana, India .
authors: Aparna
authors: A
authors: B
authors: Junior Research Fellow, Department of Microbiology, Nizam's Institute of Medical Science , Panjagutta, Hyderabad, Telangana, India .
authors: Nagapriyanka
authors: N
authors: E
authors: Professor & Head, Department of Microbiology, Nizam's Institute of Medical Science , Panjagutta, Hyderabad, Telangana, India .
authors: Vemu
authors: V
authors: Lakshmi
keywords: Combined disc test; Modified hodge test; Multiplex PCR; blaIMPblaKPCgenes; blaNDM-1; blaVIM
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