Genetic determination and characterization of extended spectrum β-lactamase producing Escherichia coli and Klebsiella pneumoniae in a tertiary care hospital, India

Extended spectrum beta lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae are known to cause nosocomial outbreaks which emerged as one of the world's extreme health threats in past two decades. In this context, the present study was aimed to isolate multi drug resistant E. coli and K. pneumoniae and evaluated the ESBL production. The samples were collected from district Govt. hospital, Ariyalur, Tamil Nadu, India in the period of September 2014 to September 2015 and a total of 1400 nosocomial isolates were isolated. All the isolates were subjected to antibiotic susceptibility testing by Kirby–Bauer disc diffusion method. E. coli (n = 160) had shown high antibiotic resistance pattern to Amikacin, Ceftazidime and Nalidixic acid while K. pneumoniae (n = 110) had shown high antibiotic resistance pattern to Ceftazidime and Nalidixic acid. Based on the phenotypic confirmatory test, 163 (60.4%) isolates (n = 89, E. coli and n = 74, K. pneumoniae) were ESBL producer. ESBL-positive isolates were screened for the presence of ESBL encoding blaTEM, blaSHV, blaCTX-M-1, blaNDM-1, blaIMP1 and blaGES resistance genes by multiplex polymerase chain reaction (mPCR). Among the ESBL producing genes, blaCTX-M-1 was the highest (90.8%) prevalence followed by blaTEM (77.3%), blaGES (19%) and blaNDM-1 (3.1%) alone or together. The present study concluded that the highest prevalence of ESBL producing MDR E. coli and K. pneumoniae with multiple resistance genes demand for new therapeutic options.