Rising threat of OXA-48 and other carbapenemase encoding genes among carbapenem resistant enterobacteriaceae in India

Abstract

Members of Enterobacteriaceae family are responsible for both community and hospital acquired infections. Because of development of antimicrobial resistance carbapenem has remained as last resort of drug for treatment of infections caused by these bacteria.Mechanism for development of this resistance in carbapenem resistant Enterobacteriaceae (CRE) may due to production of carbapenemases, efflux mechanism or loss of outer membrane porins.The most common carbapenemase enzymes are Class A – KPC, Class B – NDM, VIM and IMP and Class D oxacillinase(OXA-48 like enzymes).In India, most prevalent carbapenemase encoding gene is NDM-1but there is rising threat of OXA-48 prevalence. Unlike the phenotypic methods, the genotypic methods are useful to discriminate the type of carbapenemase enzyme, specifically for OXA-48 like enzymes. Total 170 CRE isolates were subjected for multiplex PCR study for their molecular characterization. Of the 170 CRE isolates,68.2 % (n=116) were positive for NDM-1 gene while 44.1 % (n= 75) of the isolates showed presence of OXA-48 gene. VIM (2.3%), KPC (1.7 %) were responsible for carbapenemase production while none of the isolates showed presence of IMP gene. NDM-1 and OXA-48 coexisted in 21.2 % (n=36) of the total isolates. OXA-48 causes weak hydrolysis of carbapenem because of which it is under reported with routine diagnostic methods. Early detection of OXA-48 and other carbapenemase encoding genes, helps for contact precautions and effective therapy which prevents further escalation and horizontal spread of CRE.