Varun Moktan, MD, Brian E. Lacy, MD, PhD, FACG, Andree Koop, MD, Monia Werlang, MD; Mayo Clinic, Jacksonville, FL
Background: Post-infection irritable bowel syndrome (PI-IBS) is characterized by symptoms of IBS after a viral, bacterial or parasitic gastroenteritis, and occurs in up to 25% of patients following Clostridioides Difficile infection (CDI). Polymerase chain reaction (PCR) cycle threshold (Ct) is an embedded result within a 2-step CDI testing algorithm which quantifies the bacterial burden. The amount of nucleic acid in the sample is inversely proportional to the Ct. Having a higher load of bacterium, the assay is positive at a lower value. Previous studies have also shown Ct to be a marker for clinical severity and outcomes in CDI. The aim of this study was to investigate Ct as a surrogate for bacterial and toxin burden in CDI to predict development of PI-IBS. Methods:
Methods: This was a retrospective study of hospitalized patients with an initial indeterminate C. Difficile toxin test requiring second stage confirmatory laboratory-developed PCR test. Patient demographics collected included age, sex, race, ethnicity, and body mass index (BMI). Patients diagnosed with IBS after CDI were identified by ICD10 code and PCR Ct data was collected from the microbiology lab. Continuous variables between the non-IBS and IBS groups were compared with a two-sample t test, and categorical variables using a Chi-squared test. Results:
Results: Sixty two patients underwent C. difficile PCR testing between May 2014 and October 2019. The study data is listed in Table 1. The mean age was 64 ± 16 years, and 23 (35%) were subsequently diagnosed with IBS. Mean cycle threshold in the patients who developed IBS versus the non-IBS group was 30.8±2.5 and 29.5±3.6 (Figure 1, p= 0.12) and BMI was 26.0±-5.5 versus 29.7±7.5 (p= .05) respectively. Among patients with IBS, 26% were males (Figure 2, N=6) and 95% were Caucasian (N = 22). There was a significant association between sex, lower BMI, and the development of IBS (p =.05). Discussion:
Discussion: In this retrospective cohort of patients diagnosed with CDI, PCR Cycle thresholds did not vary significantly among patients who did and did not develop IBS. Lower BMI and female sex were associated with the development of IBS. Further studies with larger cohorts are needed to determine if Ct is predictive for the development of IBS following CDI and the viability of two-step PCR testing in this scenario.
Figure 1: Cycle threshold comparison between IBS and non IBS patients
Figure 2: Differences in sex between patients who did and did not develop IBS.
Table 1: Demographic information and PCR cycle thresholds among patients who did and did not develop IBS following CDI.
Disclosures: Varun Moktan indicated no relevant financial relationships. Brian Lacy: ironwood – Consultant. Andree Koop indicated no relevant financial relationships. Monia Werlang indicated no relevant financial relationships.