A patient with fever of unknown origin has cultures ordered (urine and blood) and a broad-spectrum antibiotic. What should the nurse do?

• A. Begin antibiotic immediately
• B. Obtain specimen before beginning antibiotic
• C. Delay antibiotic until fever subsides
• D. Administer a different antibiotic

Answer: (B)

Collect the urine and blood cultures before giving the broad-spectrum antibiotic. Drawing cultures first preserves the accuracy of the results, allowing the lab to identify the actual pathogen and its susceptibilities. Starting antibiotics before cultures are obtained can kill or suppress the organisms, leading to false-negative results and making it harder to tailor therapy. In fever of unknown origin, obtaining cultures prior to antibiotic administration helps guide future treatment and supports effective, targeted care. After cultures are drawn, proceed with the antibiotic as ordered.