Colitis and diarrhoea: a problem with antibiotic therapy.

During a 19-month study the incidence of diarrhoea and colitis was estimated in 1158 orthopaedic inpatients admitted to the Guy's group of hospitals. The highest incidence of diarrhoea followed the use of lincomycin (22.2 per cent), ampicillin with cloxacillin (17.2 per cent), clindamycin (15.3 per cent) and combined therapy with cloxacillin and tetracycline (12.5 per cent). There were 3 documented cases of colitis; 2 followed lincomycin and 1 clindamycin. The incidence and relationship of antibiotic-related diarrhoea and colitis to possible aetiological factors are discussed. In orthopaedic inpatients, in whom lincomycin and clindamycin are often the antibiotics of choice, their continued use appears to be fully justified by the low incidence of colitis. However, if a patient receiving treatment with either of these antibiotics does develop diarrhoea, the antibiotic should be discontinued immediately, to reduce the risk of subsequent colitis.