Background: Recurrent Clostridium difficile infection (CDI) is a debilitating problem. We sought to determine if patients in our healthcare system had relapsing disease or reinfection by analyzing the strain types of the bacteria causing CDI. We hypothesize that typing results could imply relapse (when the patient strains are repeatedly the same), or reinfection and the need for increased infection control measures (when infection is with a new strain). To test this we did PCR ribotyping of C. difficile cultures from CDI patients who recurred at ≥60 days.
Methods: Stool was archived beginning in February 2015. Any patient with a second CDI episode ≥60 days from the original sample had both stools cultured. Toxigenic C. difficile recovered from both samples was prepared for PCR ribotyping. Isolates were grown for 24 hours and DNA extracted/ amplified following the method of Fawley et al. (PLoS One. 2015). PCR products were separated using a 3500xl genetic analyzer using GeneScan 600 LIZ as size standards. Ribotype was determined using the WEBRIBO database (https://webribo.ages.at/). Ribotype pairs were compared to each other and also to baseline data gathered from a previous study.
Results: 51 C. difficile isolates from 25 patients were typed. Twenty one patients (84%) had a second infection with the same strain and 4 (16%) had a new strain type. For patients whose second positive test was at 60-90 days, 1/13 (7.6%) acquired a new strain, and for those whose second positive test was at >90 days, 3/13 (23%) had a new strain. The number of patients with different strains vs the same was not significant (p= 0.59). In all, nineteen strain types were recovered from the 25 patients. Comparing recurrence with the same strain type to our baseline data found only 5 (20%) patients having the major clones circulating in our population. This suggests this was relapse. For the patients with a new clone, 3 of 4 were strains we had not seen previously, suggesting new CDI acquisition outside of our healthcare system or the introduction of a new clone Conclusion: Majority of the patients tested in this timeframe had relapsing disease and not new infection from exposure to our healthcare environment. Periodic typing of C. difficile isolates can help focus Infection Control efforts.
Donna Schora, MT(ASCP)1, Sanchita Das, MD2, Becky Smith, MD3, James Boone, MS4, Robert Carman, PhD5 and Lance Peterson, MD, FIDSA, FSHEA2, (1)Laboratory Medicine, and Medicine, NorthShore University HealthSystem, Evanston, IL, (2)NorthShore University HealthSystem, Evanston, IL, (3)Infection Control, NorthShore University HealthSystem, Evanston, IL, (4)TechLab Inc., Blacksburg, VA, (5)Techlab, Inc., Blacksburg, VA
None B. Smith,
None J. Boone,
None R. Carman,
None L. Peterson,