A note on antibiotic resistance in the bacterial flora of raw sewage and sewage-polluted River Tigris in Mosul, Iraq

Polluted water samples collected from the River Tigris in the vicinity of a raw sewage outfall were examined for the incidence of antibiotic resistance among coliform bacteria on three occasions during 1983. Eighty percent or more of the coliform bacteria were resistant to one or more antibiotics. At the same time, raw sewage samples were examined for the incidence of antibiotic-resistant bacteria, and Escherichia coli, Pseudomonas spp. and Staphylococcus spp. were selected for sensitivity testing. Collectively, more than 90% of the 480 strains of the three organisms were resistant to one or more antibiotics. The minimal inhibitory concentration (MIC) of ampicillin for twenty-nine strains including coliforms, E. coli, Klebsiella sp., Serratia sp., Ps. aeruginosa, Pseudomonas sp., Micrococcus sp., Staph. aureus, Streptococcus faecalis and Bacillus sp. from raw sewage and polluted River Tigris water was determined and that for Ps. aeruginosa was 250 micrograms/ml. The high incidence of antibiotic-resistant bacteria in natural waters could be related to the widespread use of antibiotics in this locality.