Erku, Woldaregay (BSC, MSC, PhD, Associate professor)Mohammed, Redwan2018-11-282023-11-052018-11-282023-11-052018-03http://etd.aau.edu.et/handle/123456789/14620Background: -Large quantities of antimicrobials are used in hospitals for patient care. Antibiotics are partially metabolized and residual quantities reach hospital sewage, exposing bacteria to a wide range of biocides that could act as selective pressure for the development of resistance. Objectives: The aim of this study was to isolate selected common bacterial pathogens and assess antimicrobial resistance of bacteria isolated from sewage released from hospitals and nonhospital sewerage system in Addis Ababa, Ethiopia Methods: A cross-sectional study was conducted from August 2016-December 2017 in hospital and non-hospital sewage. A total of 220 hospital and non-hospital sewage samples were collected twice a week for five weeks for bacteriological analysis and susceptibility testing. Pathogenic and potentially pathogenic bacteria were isolated on selective bacteriologic media and antibiotic susceptibility tests were performed using Kirby-Bauer disk diffusion method. All methods were used according to standard methods for examination of water and wastewater. Results: A total of 220 waste water samples were processed for the presence of drug resistant pathogens. From these total samples 506 bacterial isolates were isolated and of these 327 (64.6%) were from hospital environment and 179 (35.4%) were from non-hospital environment. The most frequently identified bacterium was Pseudomonas spp. 160(31.6%) followed by E.coli 108(21.34%); Klebsiella spp.76 (15%); Citrobacter spp. 50 (10%); Staphylococcus aureus 37 (7.3%);Enterobacter 14(2.8%); and 57(11.26%) were other gram positive and gram negative bacteria. Hospital and non-hospital isolates were subjected to antimicrobial susceptibility testing. The percent of resistance for Gram-negative bacteria to 9 antibiotics were as follows: Ampicillin (100% and 95.5%), Imipenem (0% and 0%), Ceftriaxone (75% and 26.9%), Ceftazidim (91.9% and 65.7%), Gentamicin (17.7% and 4.5%), Ciprofloxacin (36.2% and 8.9%), Kanamycin (27.3% and 4.5%), Chloramphenicol (19.6% and 6%) and Cefotaxime (96.5% and 89.9%)for hospital and non-hospital wastewater, respectively. Likewise, the rate of resistance for S.aureus against tested drugs was: Ampicillin (100% & 100%), Amoxicillin (100% & 83%) Chloramphenicol (28% & 17%), Ciprofloxacin (16% & 8%), Ceftriaxone (20% & 8%), Gentamicin (12% & 0%), Cefotaxim (40% & 25%), and Erythromycin (20% & 0%) for bacteria isolated from hospital and non-hospital wastewater, respectively. Conclusion: This study showed that both hospital and non-hospital environments harbor similar types of bacteria, but the hospital environment contains significantly higher number and antibiotic resistance rates of each bacteria types. The contamination of hospital sewage more than that of the non-hospital one by antibiotics or other pollutants lead to the rise and dissemination of multidrug resistance due to selection pressure.en-USHospital environment, Antimicrobial resistance, Non-hospital environment, WastewaterThesis