Clostridium difficile in a HIV-infected cohort: Incidence, risk factors, and clinical outcomes

Objective: Clostridium difficile is the most commonly reported infectious diarrhoea in HIV-infected patients in the United States. We set out to determine the incidence, risk factors and clinical presentation of C. difficile infections (CDIs) in a cohort of HIV-infected individuals. Design: We performed a nested, case-control analysis with four non-CDI controls randomly selected for each case. Methods: We assessed the incidence of CDI in the Johns Hopkins HIV Clinical Cohort between 1 July 2003 and 31 December 2010. Incident cases were defined as first positive C. difficile cytotoxin assay or PCR for toxin B gene. We used conditional logistic regression models to assess risk factors for CDI. We abstracted data on the clinical presentation and outcomes from case chart review. Results: We identified 154 incident CDI cases for an incidence of 8.3 cases per 1000 patient years. No unique clinical features of HIV-associated CDI were identified. In multivariate analysis, risk of CDI was independently increased for CD4⁺ cell count of 50 cells/ml or less [adjusted odds ratio (AOR) 20.7, 95% confidence interval (CI) 2.8- 151.4], hospital onset CDI (AOR 26.7, 95% CI 3.1-231.2) and use of clindamycin (AOR 27.6, 95% CI 2.2-339.4), fluoroquinolones (AOR 4.5, 95% CI 1.2-17.5), macrolides (AOR 6.3, 95% CI 1.8-22.1), gastric acid suppressants (AOR 3.1, 95% CI 1.4-6.9) or immunosuppressive agents (AOR 6.8, 95% CI 1.2-39.6). Conclusion: The incidence of CDI in HIV-infected patients was twice that previously reported. Our data show that compromised cellular immunity, as defined by CD4⁺ cell count of 50 cells/ml or less, is a risk factor for CDI. Clinicians should be aware of the increased CDI risk, particularly in those with severe CD4 ⁺ cell count suppression.