[Clinical and epidemiological study of adult patients with positive blood cultures]

A cohort evaluation of the microbiology, epidemiology and outcome of adult patients with positive blood cultures was performed on 336 patients, from July 1997 to March 2000. Data for mortality were obtained from 328 of these patients. The six most common pathogens were Staphylococcus aureus: 81 (23.5%), coagulase negative staphylococci: 50 (14.5%), Escherichia coli: 48 (14.0%), Streptococcus pneumoniae: 30 (8.7%), enterococci: 19 (5.5%) and Pseudomonas aeruginosa: 19 (5.5%). In 169 episodes infections were hospital-acquired and community-acquired in the remaining 159. Main infection foci included the respiratory and urinary tracts. Infection associated mortality was 33.2%; 29.6% of patients received inappropriate empiric antibiotic treatment. Univariate analysis showed that an age of 70 or more years, a systemic inflammatory response syndrome (SIRS) score higher than 2, a polimicrobial episode, certain foci (abdominal, respiratory or unknown), and an inappropriate empiric antibiotic treatment influenced outcome. By multivariate analysis the variables that influenced death by infectious cause were age of 70 or more years, a SIRS score higher than 2, certain foci (abdominal, respiratory or unknown), and an inappropriate empiric antibiotic treatment. SIRS score was useful to predict the positivity of the blood culture. No relation between outcome and presence of underlying disease, isolation of Gram negative microorganism and nosocomial vs. community acquired episode was observed (univariate analysis). In order to improve outcome in bacteremic patients, after performing cultures of blood and other relevant clinical foci, prompt and appropriate antibiotic treatment remains critical. Microbiologic, clinical and epidemiological information results crucial for the management of this critically ill population.