Antibiotic resistance of Escherichia coli from non-hospital environments - 1. Frequency and determinants of ampicillin resistance

THE frequency of ampicillin resistance in Escherichia coli in 180 samples of sea water taken from Galway City bathing beaches between February 1972 and July 1973 was determined. The log mean value was 17 per cent. In 1004 ampicillin resistant strains isolated, 13 per cent were resistant to five more antibiotics, tetracycline, neomycin, streptomycin, kanamycin and chloramphenicol. Nineteen per cent were resistant to four other drugs; 24 per cent to three others; 18 per cent to two others; 14 per cent to two others and only 12.5 per cent were resistant to ampicillin alone. Two hundred and forty-three strains were tested for their ability to transfer their resistance and 80 per cent had that ability.