Antibiotics and the Aberdeen typhoid outbreak in 1964.

This paper gives an abbreviated account of part of a research programme which followed the Aberdeen typhoid outbreak in 1964. Chloramphenicol, the main antibiotic used in treatment, was shown to have a minimum inhibitory concentration (MIC) of between 5 and 2-5 mug./ml. for the S. typhi phage type 34 of the outbreak. The MIC for methacycline was between 5 and 2-5 and 2 mug./ml. Whereas the deep and shallow broth techniques used gave similar results with these antibiotics, the MIC for ampicillin, and also cephaloridine, was less in the deep than in the shallow broths. Serum assays in patients given ampicillin or cephaloridine yielded abnormally high concentrations of both antiboitics when S. typhi phage type 34 was the test organism whereas, with other test organisms, the concentrations were within expectation. These abnormally high values fell within expected values when the sera under investigation had first been heated to 56 degrees C. for 30 min. before assay against the S. typhi of the outbreak. The findings with ampicillin suggested that dosages given were satisfactory. With cephaloridine the concentrations found in patients' sera seemed to show that twice daily doses of 0-5 g. fell short of adequacy.