DRUG-RESISTANCE IN SALMONELLA STRAINS ISOLATED FROM DOMESTIC WASTE-WATER BEFORE AND AFTER TREATMENT IN STABILIZATION PONDS IN AN ARID REGION (MARRAKECH, MOROCCO)

Some 118 Salmonella strains isolated before and after treatment in sta bilization ponds were tested for antimicrobial resistance. Tn the trea tment plant, which decreases the abundance of Salmonella by 99%, a sig nificantly lower level of antibiotic resistance (P < 0.01) was identif ied at the system's inflow point (19%) than at its outflow (29%). The serotypes most frequently identified as having multiple antibiotic res istance were Salmonella paratyphi B and S. typhimurium. High tetracycl ine resistance was observed at all sampling points, followed by resist ance to ampicilin and streptomycin. Antibiotic resistance can be trans ferred from Salmonella to other members of the Enterobacteriaceae fami ly, such as Escherichia coli K12; transfer frequencies in nutrient bro th and filtered sewage water were 4.5 x 10(-4) and 7 x 10(-7), respect ively.