CLINICAL UTILITY OF BLOOD CULTURES IN ADULT PATIENTS WITH COMMUNITY-ACQUIRED PNEUMONIA WITHOUT DEFINED UNDERLYING RISKS

Study objective: We retrospectively examined the clinical utility of obtaining routine blood cultures before the administration of antibiotics in certain non-immunosuppressed patients with community-acquired pneumonia (CAP) admitted to the hospital during 1991. Design: Retrospective review. Setting: Grady Memorial Hospital (a county hospital primarily serving inner-city Atlanta). Patients or participants: Hospital discharge diagnosis listings identified 1,250 adults (greater than or equal to 18 years old) with pneumonia. From this group of patients, we selected patients admitted to the hospital with (1) respiratory symptoms and a lobar infiltrate on chest radiograph that were present at the time of hospital admission, (2) two or more sets of blood cultures obtained within 48 h of hospital admission, and (3) absence of defined risk factors: HIV-related illness, malignancy, recent chemotherapy, steroid therapy, sickle cell disease, nursing home residence, or hospital stays within the past 14 days. Measurements and results: Five hundred seventeen patients (mean age, 52 years; age range, 18 to 103 years) qualified. Of these 517 patients, 25 patients (4.8%) had growth in blood cultures considered contaminants while 34 (6.6%) had blood cultures positive for the following pathogens: 29 Streptococcus pneumoniae, 3 Haemophilus influenzae, and 1 Streptococcus pyogenes, 1 Escherichia coli. Antibiotic therapy was changed for ? of the 34 patients with positive blood cultures (1.4% of study patients). Antibiotic regimens were altered in 48 additional patients based on sputum culture, poor clinical response, and allergic reactions. Conclusions: Few blood cultures were positive for likely infecting organisms in adult patients with CAP without defined underlying risk factors. Furthermore, a total of $34,122 was spent on blood cultures at $66 per patient. In this carefully defined group of patients, blood cultures may have limited clinical utility and questionable cost-effectiveness.