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Excerpt
Information was collected on 525 HIV-1 patients with reported diarrhoea who presented to the Chelsea and Westminster Hospital, London, from 1 January 2000 to 1 September 2001. Stool examination was performed and this entailed bacterial culture, a stool smear for ova, parasites and cysts, acid-fast staining, Clostridium difficile toxin and rotavirus antigen detection. Staining for microsporidia was undertaken if the CD4 cell count was less than 100 cells/mm3 and electron microscopy for enteric viruses was performed on request. The diagnostic yield of stool analysis was reviewed in three groups of patients depending on their CD4 cell count at the time of diarrhoea (Table 1), such that group 1 included those individuals with a CD4 cell count of 200 cells/mm3 or less, group 2 included those with a CD4 cell count of 200–350 cells/mm3, and group 3 contained those with higher CD4 cell counts, defined as 350 cells/mm3 or greater.
In those patients with the lowest CD4 cell count (group 1) stool examination was diagnostic in 30 cases (35%), the commonest diagnosis being cryptosporidiosis. It was found that 12 out of these 30 patients (40%) were receiving HAART at the time of diarrhoea. Groups 2 and 3 had similar diagnostic yields on stool examination, the commonest causes being giardiasis and Campylobacter. Approximately two-thirds of patients in groups 2 and 3 were receiving HAART, although in all three groups, patients on HAART diagnosed with cryptosporidiosis (n = 5) had detectable viral loads.
As most stool studies were not diagnostic, any patient with persistent diarrhoea for more than 4 weeks and at least two negative stool studies was referred for endoscopy (n = 64, Table 2). Upper gastrointestinal endoscopy (with gastric/duodenal biopsies) and lower gastrointestinal endoscopy (flexible sigmoidoscopy/ colonoscopy with colonic biopsies) was performed in 40 and 38 patients, respectively; 14 individuals underwent both. Upper gastrointestinal endoscopy was diagnostic in 30% and lower endoscopy in 50% of individuals in whom it was performed. Three patients were diagnosed with lymphoma on the basis of biopsy results (Table 2).
This study indicates that the cause of diarrhoea continues to be influenced by the CD4 cell count. In patients with higher CD4 cell counts, the diagnostic yield on stool examination decreased to 24% (group 2) and 25% (group 3). Infectious causes appear to be less common than non-infectious causes of diarrhoea in the HAART era, and the diagnostic yield of stool analysis decreases in patients with higher CD4 cell counts.
Effective HAART helps to eradicate opportunistic protozoal infection, and this is associated with the influx of CD4 positive cells into the lamina propria [7]. Previous algorithms have suggested that either gastroscopy or colonoscopy with biopsy should be performed in patients with persisting diarrhoea to uncover a variety of pathogens [8] that may be difficult to detect by stool analysis. This study supports this, and diagnostic yields of endoscopy are in agreement with previous results [9]. Although cytomegalovirus virus infection remains an important cause ofr diarrhoea in late disease, the three patients diagnosed here in group 3 were not receiving HAART.
