Determination of Antibiotic Resistance Spectrum in Enterobacteriaceae and Staphylococcus Bacteria Isolated from Hospital Wastewaters in Tabriz, 2015

Background Entrance of antibiotics into the sewage and water sources could eventually lead to the development of resistance among bacteria and challenges the treatment of bacterial infections. The aim of this study was to evaluate the antibiotic resistance in bacteria isolated from hospital wastewater.
Methods In a cross sectional study, in addition to count the number of coliforms, gram-negative bacilli, staphylococci and heterotrophic bacteria in sewage discharged from three hospital of Tabriz university of medical sciences, genus of bacteria were determined using selective culture media, standard biochemical tests and by API E20 detection kits. Antibiotic susceptibility tests were performed using the Kirby-Bauer disc diffusion method.
Results The results showed significant differences in the number and diversity of bacteria in wastewater discharged from the studied hospitals. Klebsiella spp., staphylococci spp. and enterobacter spp. are the most frequent genera. The antibiotic resistance in the isolated genera were between 0 to 67%. The mean of resistance to the antibiotics was between 40 to 57% and the highest resistance was obtained for penicillin members. Except for enterobacter spp. the difference in resistance in the other isolates were significant between hospitals.
Conclusion Hospital wastewater is a major source of antibiotic resistant bacteria entrance to the environment and the occurrence of isolates and the resistance pattern will vary according to the hospital type and wastewater characteristics.