How long will a patient have leukocytosis (elevated white blood cell count) with Clostridioides difficile (C. diff) infection?

Leukocytosis (elevated white blood cell count) associated with Clostridioides difficile (C. diff) infection typically persists for about 5-7 days after starting appropriate treatment, though this can vary based on individual factors. The elevated white blood cell count usually begins to normalize within the first week of effective antibiotic therapy such as oral vancomycin (125 mg four times daily for 10 days), fidaxomicin (200 mg twice daily for 10 days), or metronidazole (500 mg three times daily for 10 days) for milder cases. In severe infections or in patients with compromised immune systems, leukocytosis may persist longer, sometimes up to 2 weeks. The white blood cell elevation occurs as part of the body's inflammatory response to the toxins produced by C. diff bacteria in the intestine. Monitoring the trend of white blood cell counts rather than a single value provides better insight into treatment response. Persistent leukocytosis beyond 7-10 days may indicate treatment failure, complications such as toxic megacolon, or the presence of another concurrent infection, and should prompt clinical reassessment.