['To determine the influence of blood culture and susceptibility results and antimicrobial allergy history on fluoroquinolone use in the treatment of community-acquired pneumonia.', 'Retrospective analysis of medical records.', 'Centers for Medicare and Medicaid Services, Seattle, Washington.', 'A total of 10,275 Medicare beneficiaries hospitalized with the diagnosis of pneumonia received antimicrobial treatment within 24 hours of admission. Of these patients, 288 had blood cultures positive for pneumococcus and were matched one-to-one with patients with negative blood and sputum cultures.', 'Antimicrobial use at the beginning and end of hospitalization, culture and susceptibility results, and patient allergies were recorded retrospectively and compared between two matched groups: patients with blood cultures positive for Streptococcus pneumoniae and those whose blood and sputum cultures were negative. Neither culture and susceptibility results nor allergy history affected the rate of fluoroquinolone use. Despite infection due to penicillin-susceptible pneumococci and no penicillin allergy, patients received therapy with fluoroquinolones (26.7%) as frequently as those with culture-negative pneumonia (34.9%; p=0.401).'] Do blood culture and susceptibility results and allergy history influence fluoroquinolone use in the treatment of community-acquired pneumonia?