Comparison of multiplex PCR against blood cultures for the identification of microorganisms in a cohort of patients with bloodstream infections

Blood Stream Infections (BSI) represent an important cause of morbidity and mortality worldwide. Most treatment decisions in these cases are made taking into consideration the results of blood cultures, which has been the most important diagnostic procedure to identify the causal agent when there is a clinical suspicion of BSI. However, there is a significant delay in results when conventional methods like these are performed.1 This diagnostic method, based on the isolation of a microorganism and its identification and susceptibility test using standard biochemical techniques, is a process that can generally take from 48 to 72 hrs, and whose performance is variable. If 2 to 4 samples are obtained (40 to 80 ml of blood) before starting antimicrobial treatment, an etiological agent is detected in 80 to 96% of cases.2 In patients with bacteremia, which frequently causes sepsis and septic shock, an early and appropriate administration of antimicrobial treatments affects directly in the patient’s prognosis.3,4 an inadequate treatment can duplicate mortality, which also increases a 7,6% each hour that therapy adjustment is delayed.5,6