The microbiology of a pharmaceutical effluent and its public health implications

The effluent of a pharmaceutical company was examined microbiologically. Its bacterial count was 2.15 x 10(5) c.f.u./ ml and there was evidence of faecal contamination with MPN of > 1800. The organisms encountered included Staphylococcus aureus, Escherichia coli, Proteus vulgaris, Serratia marcescens and Pseudomonas aeruginosa. The resistances of the 25 bacterial strains isolated from the effluent to the commonly used antibiotics were studied. About 80% of the isolates were resistant to Amoxycillin, 76% to Nitrofurantoin, 64% to Cotrimoxazole and Augmentin, 60% were resistant to Nalidixic acid, 52% were resistant to Tetracycline and O. oxacin, while resistance of 12% was obtained for Gentamicin. Among the eight antibiotics tested, seven patterns of drug resistance were obtained and all of them were multiple-drug resistance with the number of antibiotics ranging from 2 - 8. All the strains of E. coli and S. aureus had high MIC values for Cloxacillin and Amoxycillin. In all, 13 strains of the bacterial isolates had evidence for the production of beta-lactamases. The potential of the effluent in spreading drug resistance and the public health implications are discussed.