Cytomegalovirus Pseudomembranous Colitis in an Immunocompetent Patient: Case Report and Review of the Literature

Cytomegalovirus-associated pseudomembranous colitis in a kidney transplant recipient

Pseudomembranous colitis (PMC) is classically associated with Clostridium difficile infection. We report a rare case of cytomegalovirus (CMV)-associated PMC in a 52-year-old female patient who had undergone kidney transplantation more than 20 years ago and was on low dose prednisolone and ciclosporin. She presented with an acute history of fever, lethargy, vomiting and diarrhoea on admission. Computed tomography of the abdomen showed extensive colitis, and colonoscopy revealed extensive pseudomembrane formation. Multiple tests for Clostridium difficile and other common microbiological causes of colitis were negative. CMV DNAemia and colonic biopsies confirmed the diagnosis of CMV colitis. The patient responded to prompt CMV treatment, as demonstrated by clinical, endoscopic, and histological response. While CMV is a common pathogen in the solid organ transplant population that is familiar to most transplant physicians, it may present atypically as PMC. Here, we review the literature on CMV-associated PMC and its relevance to solid organ transplant recipients. To our knowledge, this is the first reported case of CMV-associated PMC in a kidney transplant recipient.

Systemic antibody response to Clostridium difficile in colonized patients with and without symptoms and matched controls

It has been proposed that patients who develop Clostridium difficile-associated disease (CDAD) do so because they are unable to mount an adequate immune response. Serum was collected from three groups of elderly in-patients: (i) cases (n=21) of CDAD, being toxin A/B-positive; (ii) carriers (n=21) asymptomatic for CDAD (no diarrhoea) but at least toxin or culture positive; and (iii) controls (n=26) asymptomatic for CDAD and negative for both C. difficile toxin and culture. The age and gender of each group were compared, and the colonizing strains were ribotyped and toxinotyped. Serum antibodies (IgG and IgM) were measured by ELISA using different antigen preparations: EDTA extract (containing cell-surface proteins and carbohydrates), guanidine hydrochloride extract (surface-layer proteins), aqueous phenol-extracted lipocarbohydrate (LC); crude toxin (dialysis culture supernatant) and purified toxin A. LPS from Escherichia coli was used as a control antigen. Antibodies were also tested for toxin neutralization on tissue monolayers and for binding to EDTA-extracted antigens by Western blotting. IgG antibody measurements to cytomegalovirus (CMV) were included as an indicator of potential immunosenescence. Results showed that the patient groups were well matched by age and gender, and the colonizing strains were similar in cases and carriers, being predominantly ribotype 001 and toxinotype 0. By ELISA, IgG levels to most of the antigens were highest in the cases and lowest in the controls, with the exception of antibodies to the LC, which were higher in the controls than the cases. Levels in the carriers tended to be of intermediate level or similar to the controls. For all antigens, the levels of IgM were not significantly different among cases, carriers and controls. Serum from all groups was able to neutralize the cytotoxic action of toxin on both Vero and Caco2 cells, and all to a similar extent. Western blots showed an overall higher level of IgG antibodies to the EDTA-extracted antigens in the cases. The results of the CMV ELISA showed that specific IgG was detected in more cases (78%) than carriers and controls (both 65%), but this difference in seropositivity was not significant. The conclusion is that, during symptomatic infection, patients respond to protein antigens of C. difficile in a manner typical of a secondary antibody response, with no evidence that an inability to respond predisposes to the appearance of symptoms.

Cytomegalovirus colitis in a critically ill patient following elective repair of an abdominal aortic aneurysm

We describe a case of cytomegalovirus colitis in a critically ill but otherwise immunocompetent 61-year-old male. Infection was demonstrated by histology and confirmed by plasma polymerase chain reaction and detection of cytomegalovirus IgM antibody. The patient was treated with ganciclovir with resolution of the cytomegalovirus viraemia. Cytomegalovirus colitis may be an under-recognised problem in immunocompetent patients who are critically ill. Quantification of plasma cytomegalovirus DNA by polymerase chain reaction is a non-invasive method of supporting the diagnosis and can be used to monitor the treatment of cytomegalovirus infection in the immunocompetent.