Relationship of Campylobacter toxigenicity in vitro to the development of postinfectious irritable bowel syndrome

Campylobacter enteritis is associated with a significant risk of developing irritable bowel syndrome, but the mechanism is unknown. This study ascertained bowel symptoms in 93 patients 3 months after Campylobacter jejuni enteritis infection. The infecting organisms were cultured, and the effects of culture supernatants on toxin-sensitive epithelial cell monolayers (HEp-2, Green monkey kidney epithelial [Vero], and CHO-K1) were investigated. In all, 50, 43, and 41 of the isolates showed toxigenic effects on HEp-2, CHO-K1, and Vero cells, respectively. Persistently changed bowel habit was reported by 9 of 50 persons with HEp-2 toxin-positive infections but by only 2 of 43 with isolates negative for toxin (chi2=4.0; P<.05). Toxicity to HEp-2 and Vero cells was associated with significantly increased numbers of days with loose stools 6 months after C. jejuni enteritis infection (both, P<.05). Thus, long-term symptoms that occur Campylobacter infection are significantly associated with bacterial toxicity.

Increased rectal mucosal enteroendocrine cells, T lymphocytes, and increased gut permeability following acute Campylobacter enteritis and in post-dysenteric irritable bowel syndrome

BACKGROUND AND AIMS

Post-dysenteric irritable bowel syndrome (PD-IBS) develops in up to 25% of patients following Campylobacter enteritis. Our aim was to define the pathological basis of this subgroup of IBS.

METHODS

Twenty one patients (group 1) underwent serial rectal biopsy and gut permeability testing following acute Campylobacter enteritis as did 10 PD-IBS patients (group 2) and 12 asymptomatic controls.

RESULTS

In group 1, enteroendocrine cell (EC) numbers were markedly increased initially and at six and 12 weeks (p<0.001) compared with controls. Gut permeability, as assessed by the lactulose/mannitol ratio, was significantly elevated, initially and at 12 weeks (p<0.005). CD3, CD4, and CD8 lymphocyte counts in the lamina propria and intraepithelial lymphocytes (IEL) were significantly increased initially compared with controls. At visit 1, EC numbers were positively correlated with CD3 counts (r=0.6, p=0.01). At one year, seven subjects (five with persistent loose stools) had rectal biopsies which showed significantly elevated EC, CD3, and IEL counts. In group 2, EC and IEL counts were significantly increased compared with controls (p<0.001), as was gut permeability (p<0.01).

CONCLUSION

Increased EC, T lymphocytes, and gut permeability are acute changes following Campylobacter enteritis which can persist for more than a year and may contribute to PD-IBS.

Adherence of Aeromonas caviae to human cell lines Hep-2 and Caco-2

Adherence of Aeromonas caviae to HEp-2 and Caco-2 cell monolayers was investigated with 24 clinical isolates. Growth phase, temperature, multiplicity of infection and length of incubation affected adherence. Treatment of the bacteria with trypsin, sodium metaperiodate, mechanical shearing and the addition of cytochalasin B and cycloheximide to the monolayer significantly reduced the adherence capabilities of the strains investigated. The use of chloramphenicol to inhibit protein synthesis reduced the adhesive capabilities of bacteria grown in liquid medium and those subjected to mechanical shearing. Light microscopy, scanning and transmission electron microscopy were employed in the investigation of bacteria-bacteria and bacteria-monolayer interactions and indicated similarities with the aggregative adherence patterns of the Enterobacteriaceae. The presence of extracellular bacterial appendages and their correlation with increased adhesive capacity may indicate a role in the process of adherence.