INTRODUCTION

Background The prevalence of extended-spectrum \(\beta\)-lactamase (ESBL) and AmpC \(\beta\)-lactamase (ABL) producing Enterobacteriaceae is increasing rapidly across the world. Members of Enterobacteriaceae like E. coli and Klebsiella spp. exhibit antimicrobial resistance mainly due to the production of beta-lactamase enzymes like extended-spectrum βlactamases, AmpC β-lactamases, and carbapenemases. These bacteria are frequently reported in sewage effluents of hospital and municipal sewerage systems indicating sewage as a promising source for dissemination of such drug-resistant pathogens. However, in most of the developing countries including Nepal, the major portion of sewage is discharged in water sources without proper treatment and disinfection. This study was undertaken to access the prevalence of ESBL and ABL producing E. coli and Klebsiella spp. in sewage effluents of Dharan, Nepal. Results A total of 235 bacteria were isolated, out of which 103 (43.83%) were E. coli and 132 (56.17%) were Klebsiella spp. ESBL production was seen in 157 (66.81%) isolates. Among them, 89 (56.69%) were Klebsiella spp. and 68 (43.31%) were E. coli. 66.02% of total isolated E. coli and 67.42% of total isolated Klebsiella spp. showed production of ESBL enzymes. ABL production was seen in 133 (56.59%) isolates. Among them, 54 (40.60%) were E. coli and 79 (59.40%) were Klebsiella spp. 52.43% of the isolated E. coli and 59.85% of isolated Klebsiella spp. were found producing ABL enzyme. Conclusions The results indicate that there is a high prevalence of ESBL and ABL producing E. coli and Klebsiella spp. in sewage effluents of Dharan. Effective treatment of sewage effluents must be ensured before discharging the sewage into the environment. National guidelines for discharging the municipal sewage must be immediately amended and an effective treatment system before discharge must be implemented. Dissemination of such drug-resistant bacteria in the human population leading to severe public health emergency is likely to occur from sewage contamination, so further study and surveillance and effective prevention and control measures are necessary.