Browsing by Author "Debadatta Dhar"

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Expansion of highly stable bla OXA-10 β-lactamase family within diverse host range among nosocomial isolates of Gram-negative bacilli within a tertiary referral hospital of Northeast India
(BioMed Central Ltd., 2017) Anand Prakash Maurya; Debadatta Dhar; Mridul Kumar Basumatary; Deepjyoti Paul; Birson Ingti; Debarati Choudhury; Anupam Das Talukdar; Atanu Chakravarty; Shweta Mishra; Amitabha Bhattacharjee
Background: The current study reports dissemination of highly stable bla OXA-10 family of beta lactamases among diverse group of nosocomial isolates of Gram-negative bacilli within a tertiary referral hospital of the northern part of India. Methods: In the current study, a total number of 590 Gram negative isolates were selected for a period of 1 year (i.e. 1st November 2011-31st October 2012). Members of Enterobacteriaceae and non fermenting Gram negative rods were obtained from Silchar Medical College and Hospital, Silchar, India. Screening and molecular characterization of β-lactamase genes was done. Integrase gene PCR was performed for detection and characterization of integrons and cassette PCR was performed for study of the variable regions of integron gene cassettes carrying bla OXA-10. Gene transferability, stability and replicon typing was also carried out. Isolates were typed by ERIC as well as REP PCR. Results: Twenty-four isolates of Gram-negative bacilli that were harboring bla OXA-10 family (OXA-14, and OXA16) with fact that resistance was to the extended cephalosporins. The resistance determinant was located within class I integron in five diverse genetic contexts and horizontally transferable in Enterobacteriaceae, was carried through IncY type plasmid. MIC values were above break point for all the tested cephalosporins. Furthermore, co-carriage of bla CMY-2 was also observed. Conclusion: Multiple genetic environment of bla OXA-10 in this geographical region must be investigated to prevent dissemination of these gene cassettes within bacterial population within hospital settings. © 2017 The Author(s).
Occurrence of co-existing bla VIM-2 and bla NDM-1 in clinical isolates of Pseudomonas aeruginosa from India
(BioMed Central Ltd., 2016) Deepjyoti Paul; Debadatta Dhar; Anand Prakash Maurya; Shweta Mishra; Gauri Dutt Sharma; Atanu Chakravarty; Amitabha Bhattacharjee
Background: bla VIM-2 harboring Pseudomonas aeruginosa has been reported worldwide and considered as the most prevalent metallo-β-lactamase after NDM which are found horizontally transferable and mostly associated with integron gene cassettes. The present study investigates the genetic background, transmission dynamics as well as stability of bla VIM-2 in clinical isolates of P. aeruginosa harbor bla NDM-1 as well which were collected from October 2012 to September 2013. Methods: Two P. aeruginosa strains harboring bla VIM-2 along with bla NDM-1 were isolated from Silchar Medical College and Hospital, India. Genetic environment of these resistance determinants was determined and transferability was checked by transformation and conjugation assay which was further confirmed by Southern hybridization. Replicon typing was performed to determine the incompatibility group of the resistant plasmid and their stability was checked by serial passage method. Antimicrobial susceptibility pattern of the isolates was determined and their clonal relatedness was checked by pulsed field gel electrophoresis. Results: bla VIM-2 was found to be horizontally transferable through an Inc F type plasmid of approximately 30 kb in size. bla VIM-2 was found to be associated with integron gene cassette and was flanked by two different types of cassette arrays. Both the isolates were co-harboring bla NDM-1 which was carried within Inc N type of plasmid with an approximate 24 kb in size and associated with ISAba125 in their upstream region. Reduced susceptibility rate as well as high MIC range was observed in case of wild strains and transformants carrying bla VIM-2 and bla NDM-1. Conclusions: The detection of this co-existence of multiple carbapenem resistance genes in this part of world is worrisome and further investigation is required in order to trace the source and to initiate proper treatment option. © 2016 The Author(s).