Molecular Analysis of Clostridium difficile, C. difficile 027/B1/NAP1 and Vancomycin-Resistant Enterococci (VRE) in Tissues with Pseudomembranous Colitis or CDAD
C Chisholm, D Smith, G Frederick, K Hocker, A Rao. Scott & White Memorial Hospital and Texas A&M Health Sciences Center, Temple, TX; University of Mary Hardin-Baylor, Belton, TX
Background: CDAD (Clostridium difficile associated colitis) can present with disease ranging from diarrhea to severe pseudomembranous colitis (PMC). The identification of a unique strain, 027/B1/NAP-1, with a mutation in the negative regulator tcdC gene, is associated with increased virulence. We investigated the prevalence of C. difficile with toxin A and B genes, the 027/B1/NAP1 strain and the presence of VRE organisms in biopsies submitted from CDAD symptomatic patients.
Design: 90 paraffin-embedded surgical pathology specimens associated with patients with clinical pseudomembranous colitis or CDAD were analyzed for the presence of VRE and C. difficile by PCR identifying toxin A and B genes. A separate PCR analysis identified the 027/BI/NAP1 mutation. All corresponding C. difficile toxin EIA and stool PCR results were collated from the records.
Results: 45 tissue samples had PMC in the histological diagnosis. 25 of these had molecular evidence of VRE or C. difficile and stool PCR, toxin EIA, and tissue PCR were positive in 86%, 60%, and 38% of these patients with both toxins A and B genes identified. Only 1 patient was positive for the 027/B1/NAP1 mutation. Interestingly, in 7 of the 45 PMC patients, VRE alone was detected both in tissue and stool. 8 patients had both C. difficile and VRE in tissue and/or stool. When both organisms were identified, the average white blood cell count was 37 as compared to those with only VRE or C. difficile (24.3 and 22.0). Worse renal function and increased morbidity was correlated with VRE. 45 additional samples had a clinical diagnosis of CDAD but had no histological changes of PMC. Only 3 of these were positive by molecular analysis for C. difficile and/or VRE.
Conclusions: C. difficile 027/B1/NAP1 was seen in only 1 case, while 2 patients had an alternate tcdC allele B. Thus, VRE emerged as a major contributor to morbidity and mortality in patients with PMC even when compared to the virulent C. difficile strains. It is likely an under-recognized causal agent and it may be critical to examine patients for VRE.
Monday, March 22, 2010 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 202, Monday Morning