The antibiotic sensitivity of bacteria isolated from the blood of patients in St Thomas' Hospital, 1969-1988.

We have monitored the antibiotic sensitivity of bloodstream isolates of common bacteria over a period of 20 years. Among the Gram-positive bacteria, the proportion of isolates of Staphylococcus aureus resistant to methicillin, erythromycin, fusidate, or gentamicin has increased marginally, while that of coagulase-negative staphylococci (mostly Staph. epidermidis) has increased markedly. Enterococci are becoming serially more resistant to high concentrations of aminoglycosides. The Enterobacteriaceae have become considerably less sensitive to ampicillin (and amoxycillin) and trimethoprim but more sensitive to the aminoglycosides, whilst their susceptibility to cefotaxime, ceftazidime, cefepime, cefpirome, imipenem, meropenem and temocillin has remained constant. We have some evidence that in-vitro resistance is clinically relevant since the mortality rate rises if inappropriate antibiotics are used empirically. Although many drug regimens could be used, we are able to recommend initial therapy with a combination of gentamicin and cefuroxime for most of our patients, the exceptions being those known to be infected with resistant organisms before the onset of septicaemia.