DISCUSSION In this study E. coli, E. aerogenes, P. aeruginosa, S. aureus and S. pyogenes were isolated and identified from Keha and Shinta rivers. The isolation of these human pathogens in these rivers water is a source of fear, since the water is consumed by the surrounding society. The consumption of such contaminated materials may facilitate widespread infections and can ultimately lead to the outbreak of epidemics. The effluent of river water, which is discharged into nearby water bodies contaminates streams, food crops on the farm and inadvertently reaches man (Khan and Malik, 2001). The isolation of these bacteria from these rivers may be due to discharging of human and animal wastes to the river. The widespread emergence of antibiotic resistance, particularly multidrug resistance, among bacteria has become one of the most serious challenges in clinical therapy (Baker et al., 2009; Jose, 2012). Environments containing antibiotic residues exert selection pressure and contribute to the appearance of resistant bacteria. In light of the potential health risk, many studies have focused on antibiotic-resistant bacteria from various ecosystems (Reinthaler et al., 2003; Osman et al., 2007; Mesa et al., 2006). In the present study, the isolated bacteria were checked for their antibiotic susceptibility and pattern of resistance to antibiotics such as: Amp, Cip, Te, CRO, Van, Amc, Rd, E, Pen, Oxc and Gen. The Shinta river has become the ultimate dumping ground of Dashen brewery, municipal, and agricultural sewage and Keha is also a reservoir of Gondar university teaching hospital, municipal and agricultural sewage thus posing significant threat to ecological balance as well as to public health. Hospital, municipal and agricultural ... ... middle of paper ... ... 2009 and this prevalence was lower than the report of Lin and Biyela (2005), which showed that 58% of multi drug-resistant isolates with aquatic environments contained class 1 integron. Class 1 integron was found in 5 (31.3%) of 16 P. aeruginosa isolates from Keha and Shinta river water. This prevalence was in line with Henriques et al., 2006, who identified class 1 integron in 29.6% of Enterobacteriaceae isolated from estuarine waters. All of the isolates that carried class 1 integrons were resistant to Ampicillin and most of them are resistant to ciprofloxacin and Tetracycline (Table 10). Class 2 integron was not detected in any of the isolates in this study. However Emilie et al., 2009 identified class 2 integrons in 1.4% of E. coli isolated from the Seine estuary and Maria et al., 2010 detected the intI2 gene in only 1 (0.6%) of 162 environmental isolates