[Coagulase-negative Staphylococcus bacteraemia: prognosis factors and influence of antibiotic treatment]

Coagulase-negative staphylococci (CNS) are the most frequent isolated microorganism in blood cultures; mortality has been associated to severity and to adequacy of empirical treatment but the relevance of the latter is not clearly recognised. The aims of the study were to analyze clinical and microbiological factors related to mortality in patients with CNS bacteraemia and the influence of empirical treatment in prognosis.

A prospective cohort study of patients with CNS bacteraemia was performed (January to June 2010) at a university-affiliated hospital; a determination of clinical significance was made and true bacteraemia was defined according to CDC criteria. We analysed epidemiological, clinical and microbiological variables related to mortality.

A total of 269 cases were included (97 were considered true bacteraemia); 92% survived and mortality was 8% (1.6% CNS bacteraemia related mortality). Staphylococcus epidermidis was the most frequent isolated species; 93 patients were included in the related mortality study of patients with true bacteraemia. Factors associated to mortality in the bivariate analysis (p<0.05) were: Winton score I-III, presence of pacemakers, sepsis or infective endocarditis and persistent bacteraemia. Adequate empirical treatment was not associated to survival.

Severity at onset, the development of septic complications and having a pacemaker are associated to mortality in patients with CNS bacteraemia; in our cohort, inadequate empirical treatment is not related to mortality.