An ongoing dilemma in treating patients with suspected sepsis has existed for years. In most cases, antibiotics is the first treatment, but which antibiotics should be given?

Some physicians, especially internal medicine or infectious disease specialists, want to know which organisms are causing the infection before deciding on which antibiotics to use. Using the wrong antibiotic can be a waste of time and delay proper treatment. Emergency room physicians, on the other hand, view prompt initiation of antimicrobial therapy as a critical determinant of survival.

The controversy was clouded by lack of knowledge of how quickly blood cultures lose their ability to grow organisms after antibiotics are given. A recent study done by Brigham and Women’s Hospital in Boston, described in *Annals of Internal Medicine*, found that if a doctor wants an accurate reading from sepsis patients’ blood cultures, starting antibiotics before you’ve drawn the blood samples can mean a significant reduction in accuracy of the cultures.

In general, the accuracy of blood cultures taken before antibiotic treatment were positive for specific pathogens in 31.4% of patients, compared with 19.4% when antibiotic treatment had already been started. One result of the study was the finding that even when cultures are performed very rapidly after antibiotics, they lose much of their diagnostic accuracy.

Of course, this has not resolved the ongoing controversy. Experts acknowledge the higher diagnostic value of blood cultures prior to giving antibiotics, but warn of “unintentional treatment delays” given the higher risk for death associated with a delay in treatment. Further studies are needed to determine which patients should have blood drawn before antimicrobial treatment and which can withstand the delays resulting from waiting for culture results. And clinicians are urged to emphasize the need for very rapid blood cultures so the delay before starting antibiotics is as short as possible.