CHICAGO – A simple clinical prediction rule effectively detected a majority of asymptomatic carriers of Clostridium difficile infection in a long-term care facility, results from a small single-center study found.

According to the rule, which was derived from an article in the infectious diseases literature, previous C. difficile infection and/or antibiotic therapy within the past 3 months is helpful in predicting asymptomatic carriers (Clin. Infect. Dis. 2007;45:992-8). During a poster session at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy, which was sponsored by the American Society for Microbiology, the researchers, led by Lucy Jury, presented findings from a study that set out to test the value of the prediction rule in a long-term care setting.

Ms. Jury, a nurse practitioner with the geriatric research, education, and clinical center at the Louis Stokes Cleveland Veterans Affairs Medical Center, and her associates conducted a 5-month prospective study of 120 patients who were being transferred from the Cleveland VA hospital to an affiliated long-term care facility. Rectal swabs were cultured at the time of transfer and then weekly for up to 6 weeks. The mean age of patients was 69 years, all were men, 75% had received antibiotic therapy in the past 3 months, and 39% had an indwelling catheter.

Of the 120 patients, 14 (12%) were asymptomatically colonized upon transfer to the long-term care facility. Among 85 patients with negative cultures and at least one follow-up culture, 22 (26%) acquired colonization.

Ms. Jury and her associates determined that the prediction rule had a sensitivity of 78%, a specificity of 43%, a positive predictive value of 49%, and a negative predictive value of 73%. When the researchers limited their analysis to high-risk antibiotics – including third-generation cephalosporins, fluoroquinolones, and clindamycin – the specificity rose to 82%, but the sensitivity fell to 55%.

In their poster, the researchers concluded that the prediction rule "could be used to guide infection-control interventions designed to reduce the risk for transmission from asymptomatic carriers."

Ms. Jury said that she had no relevant financial disclosures to make.