A patient with a history of Clostridioides difficile is admitted to the hospital.

The CBIC Certified Infection Control Exam Study Guide (6th edition) defines prophylactic antimicrobial therapy as the use of antibiotics to prevent infection in the absence of clinical signs or symptoms of active disease. In this scenario, the patient has a history of Clostridioides difficile infection but is currently asymptomatic for diarrhea or other CDI manifestations. The antibiotic is therefore not being used to treat active infection.

Empiric therapy (Option A) is initiated when infection is suspected but the causative organism has not yet been identified—this does not apply here, as the patient has no symptoms suggesting infection. Targeted therapy (Option D) requires laboratory confirmation of a specific pathogen, which is also not present. While prescribing antibiotics in patients with prior CDI may be clinically questionable depending on indication and stewardship principles, the type of therapy being applied is best categorized as prophylactic, not inappropriate, based on standard antimicrobial definitions.

The Study Guide emphasizes that antimicrobial stewardship programs carefully evaluate prophylactic antibiotic use because unnecessary exposure can disrupt normal flora and increase the risk of CDI recurrence. However, from a classification standpoint, antibiotics given without signs of active infection fall under prophylactic use.

For CIC® exam preparation, it is important to correctly identify antimicrobial intent, even when clinical appropriateness may be debatable.