Risk factors for acquisition of gentamicin-resistant enterococcal infection: a case-controlled study.

High-level gentamicin-resistant enterococci present problems in the treatment of infected patients, especially as synergy between penicillin and gentamicin is lost. Previous studies have suggested various risk factors for the acquisition of these enterococci. A case-controlled study was performed on 17 patients infected with resistant enterococci and 26 infected with sensitive strains who attended a London hospital. The key risk factors for acquisition of infection with high-level gentamicin-resistant enterococci were found to be prior prolonged antibiotic treatment, use of five or more antibiotics, and the presence of a urinary catheter. It is proposed that infection control measures should be targeted at patients at higher risk. In addition, control of antibiotic usage in a hospital may help to prevent acquisition and spread of these organisms.

The origin of coagulase-negative staphylococci isolated from blood cultures.

The source of coagulase-negative staphylococci (CNS) isolated from blood cultures and thought to be contaminants was investigated over a two month period. Isolates recovered from swabs taken from patients, doctors and laboratory staff were compared with the blood culture patient isolate in an attempt to identify the source of contamination. Six hundred and ninety-six blood culture sets were received of which 28 were contaminated with CNS. Nineteen of these blood cultures had sufficient data to be included in this study. Six were matched to isolates from the patient's skin and none to the medical or laboratory staff. Major differences in the antibiograms were seen between the patients, medical and laboratory staff. Organisms from patients and medical staff were more likely to have multiple antibiotic resistances. It appears that the most important source of CNS contamination of blood cultures processed in a semi-automated manner is the patient's own skin flora.