THE NEED FOR NEW MICROBIOLOGICAL WATER-QUALITY CRITERIA

The microbiological criteria for water quality have been directed towards protection of consumers from possible microbial pollution which may cause public health hazards. Therefore, the bacteriological standards for drinking water are based mainly on bacterial indicators. Another problem of prime concern to public health is the presence of antibiotic-resistant bacteria in drinking water. Antibiotic-resistant bacteria were found among standard plate count populations of chlorinated drinking water from two districts in Cairo. Most strains appeared to be ampicillin resistant (89%). Those were followed by sulfaguanidine (78%) and streptomycin (57%). The majority of the tested strains (62.4 to 98%) were multiple antibiotic resistant (MAR). Identification of 363 MAR strains revealed that Gram-positive rods were dominant, while Gram-negative fermentative rods, Gram-positive cocci and Gram-negative nonfermentative rods represent the second, third and fourth group. A total of 101 strains isolated from underground water pumped from three water works in Cairo were classified and tested for their resistance towards four commonly used antibiotics; chloramphenicol, tetracycline, neomycin, penicillin and one chemotherapeutic agent namely sulfanilamide pyrimidine. Results showed that 77, 64 and 32 isolates have resistance towards penicillin, sulfanilamide pyrimidine and tetracycline, respectively. Only 18 and 8 isolates were resistant to chloramphenicol and neomycin, respectively. It was also found that 19 isolates belonging to 6 genera or groups were sensitive towards all of the tested compounds. Therefore, any source of antibiotic-resistant bacteria must be viewed with concern and use of data on MAR bacteria should be made in future water quality deliberations and in regulating effluent quality discharges.