PCR identification of blaTEM gene mediated for ESBL drug resistance in Salmonella typhi

Abstract

Objective: The aim of the present study to identify the presence of R-plasmid and detect the blaTEM gene encodes for ampicillin resistance.

Materials and Methods: Salmonella typhi organisms isolated from widal positive blood samples and screened by standard screening methods. Antimicrobial susceptibility test by Kirby-Bauer disc diffusion method and MIC by agar dilution method for Ampicillin performed as per Clinical Laboratory Standard Institute (CLSI) guidelines. ESBL detection by phenotypic confirmatory test, Double Disc synergetic test was performed with ampicillin, ampicillin/clavulanic acid combination according to CLSI standards. Subsequently, Plasmid isolation was carried out by alkaline lysis method and identification of Ampicillin resistance encoded gene blaTEM was done with PCR by standard parameters and conditions.

Results: Among 66 S. typhi isolates, 04 (06.06%) strains were ampicillin resistant (ARST) among them 03 strains showed with increased MIC value of 256 µg/ml to 512 µg/ml. Three ARST strains chosen for the study have shown positivity for ESBL production. We observed significant increase in zone by ˃3 mm in ampicillin/clavulanic acid combination with respect to ampicillin alone in phenotypic confirmatory method. Subsequently, we observed significant enhancement in the inhibition zone of ampicillin towards the ampicillin/clavulanic acid disc is confirmed as positive for ESBL production. All 03 ARST isolates carries a R-plasmid of 16 kb size and positive for presence of blaTEM genes with amplicon size of 800kb.

Conclusion: Present study shows the transmissible R-plasmid present among Enterobacteriaceae, mostly in E. coli shares R-plasmid harbour`s ampicillin resistant gene blaTEM with S. typhi intern facilitates to develop resistance against ampicillin.

Keywords: Ampicillin, ARST, R-plasmid, ESBL, blaTEM

Cite this Article

Rahul Narasanna, Manjunath Chavadi, Ashajyoti Chavan, Kelmani Chandrakanth. PCR identification of blaTEM gene mediated for ESBL drug resistance in Salmonella typhi. Research & Reviews: Journal of Microbiology and Virology. 2016; 6(2): 1–6p.