Vascular changes in duodenal mucosa in shigellosis and cholera.

Vascular endothelial cells are highly specialized cells with numerous sensory and modulator functions. Our previous studies show extensive microvascular changes in rectal mucosal vasculature of patients with acute infective diarrhea (Mathan and Mathan 1985a, Gut 26:710-717). We looked for changes in the duodenal mucosal vasculature in two naturally occurring diarrheal infections: shigellosis and cholera. Duodenal mucosal biopsies from 14 patients with shigellosis, 12 patients with cholera, and 10 healthy volunteers were examined under the electron microscope. There were extensive microvascular changes in the duodenum in shigellosis and cholera. Congestion and dilatation of capillaries and venules, stagnation of blood, thinning of the endothelial lining, and platelet clumping were commonly seen in both conditions. Endothelial damage was also common to both conditions but was mild to moderate in cholera and severe in shigellosis with frank hemorrhage, frequent formation of stress fibers, widening of intercellular spaces, cytoplasmic blebbing, cell fragmentation, and intravascular thrombosis. Erythrocyte aggregates, platelet aggregates, and leucocyte plugging lead to capillary obstruction. The arterioles were severely constricted. These changes in the endothelial lining of the microvasculature could contribute to the pathogenesis of the disease resulting in peripheral vascular insufficiency, inadequate oxygen delivery to intestine, and organ dysfunction. The factors influencing these changes, their implications, and possible therapeutic interventions are discussed.

Faecal lactoferrin as a predictor of positive faecal culture in south Indian children with acute diarrhoea.

Faecal lactoferrin, an iron-based glycoprotein found concentrated in secondary granules of neutrophils, may serve as a surrogate marker of inflammation in the intestine. We evaluated the usefulness of faecal lactoferrin as a predictor of infection with invasive enteropathogens in 262 children with diarrhoea. Lactoferrin at a dilution of 1:50 had the highest sensitivity for detection not only of conventionally cultured invasive enteropathogens but also of all other enteropathogens. Neither individual clinical symptoms nor the identification of faecal leucocytes by microscopy significantly predicted isolation of invasive enteropathogens from the faeces of children with diarrhoea. Faecal lactoferrin is a simple test which showed promise in predicting which children with diarrhoea are likely to be infected with invasive pathogens and can be incorporated as a screening test before faecal cultures are undertaken in this population.

Epidemiological and laboratory investigations of outbreaks of diarrhoea in rural South India: implications for control of disease.

Two epidemics of acute, watery diarrhoea in villages in North Arcot district, India, were investigated. The attack rates were 10.03 and 15.53 per 100 population, the median duration was 5 days and enteric pathogens were present in 56.8% and 60.3% of specimens from the two villages, but no predominant pathogen was identified. Examination of stools from a 20% age-stratified random sample of the population of one of the villages after the epidemic found 22.9% of asymptomatic subjects excreted bacterial enteric pathogens. Despite the high background of enteric pathogen carriage, the isolation rates for shigellae, enteropathogenic Escherichia coli and Shiga-toxin producing E. coli were significantly higher (P < 0.001, P < 0.02, P < 0.05) during the epidemic. The epidemics may have been caused by faecal contamination of well water following rain. Point-of-use techniques for water disinfection may be most effective for preventing such outbreaks, but further research into the development of appropriate technology is required.

Enteroaggregative Escherichia coli infection in a rabbit model.

Type strains of enteroaggregative Escherichia coli EAEC (17-2, serotype O3:H2; JM 221, serotype O92:H33), isolates from an adult and a child with diarrhoea and an asymptomatic colonised child were used to orally infect adult rabbits. The experimental animals were followed up and sacrificed at defined time periods. Colonisation of both small and large intestine was seen with all strains and isolates used. Isolates from an adult patient with diarrhoea (MP 27) and from an asymptomatic colonised child from the community (KM 1337) were recovered from the small intestine during the first week of infection and subsequently from the large intestine. A total of seven rabbits was infected with MP 27; while colonising the gastrointestinal tract of all seven rabbits, this isolate caused diarrhoea in only one. On ultrastructural examination, the rabbits infected with 17-2 showed invasion of lymphoid follicles. Bacteria were seen in intercellular spaces and within M cells, a finding that has not previously been described. It is clearly possible to produce gut colonisation by oral infection with EAEC in adult rabbits with normal flora.

A monkey model for enterohemorrhagic Escherichia coli infection.

Adult Macaca radiata (n=22) were infected intragastrically with 10(12) Escherichia coli O157:H7 strain 84-01, which produces Shiga toxins 1 and 2. Clinical symptoms and bacterial excretion were documented in each monkey for a specified time period before they were killed. At necropsy, samples were obtained for culture and histologic and ultrastructural examination. Seventeen monkeys had diarrhea: E. coli O157 was isolated from postinfection stool samples from all monkeys and from autopsy cultures for 14 of 22 monkeys. Histologic examination showed attaching-effacing lesions, which appeared at 12 h and persisted for 7 days, in 12 monkeys. Widening of the intercellular spaces, degeneration and vacuolization of the epithelial cells, epithelial tufting, extrusion of epithelial cells, and neutrophilic infiltration were characteristic features seen in 20 of the 22 infected monkeys but not in 4 control monkeys. This monkey model closely parallels the early stages of the disease produced by E. coli O157:H7 and would be useful in the further study of pathogenic mechanisms and prevention methods in enterohemorrhagic E. coli infections.

A prospective study of nosocomial enteric pathogen acquisition in hospitalized children in South India.

Screening for enteric pathogens in stool samples from 249 children under the age of 36 months, admitted to hospital for non-gastrointestinal disorders, was positive at admission in 41 (16.4 per cent) in a prospective study of enteric pathogen acquisition and diarrhoea in hospitalized children. Infection with multiple organisms was found in 31/41 (75.6 per cent) children who were positive when screened at admission. Of 194 children who had no enteric pathogens on admission and could be followed up for 3 days after discharge, clinical or laboratory data showed nosocomial enteric infections in 39 (20.1 per cent). Presumed nosocomial infection with more than one organism was seen in only two patients and no pathogens were isolated in 14 (35.8 per cent). Children presenting to hospital may asymptomatically carry enteric pathogens and potentially act as a source of nosocomial infections. One in five children admitted into hospital without an enteric infection is at risk of developing a nosocomial gastrointestinal infection, with rotavirus being the most common aetiological agent.

Prevalence of enteroaggregative and other HEp-2 cell adherent Escherichia coli in asymptomatic rural south Indians by longitudinal sampling.

Enteroaggregative and other HEp-2 cell adherent Escherichia coli can produce acute and persistent diarrhoea in children and adults, but their prevalence in asymptomatic individuals in the community is not known. In this study, faecal specimens were obtained at 3-4 monthly intervals from 349 subjects constituting a 20% age-stratified sample of a rural community for a period of two years. HEp-2 cell adherent E. coli were found in 210 subjects, and repeat isolations of enteroaggregative E. coli belonging to the same serogroup were found in 12.6% of children less than 12 years of age, indicating that this organism can asymptomatically colonise the intestinal tract. These children may act as a reservoir of infection for the community.

Cytomegalovirus infection of the human gastrointestinal tract.

BACKGROUND: Current interest in cytomegalovirus (CMV) is largely due to an increase in the number of cases of acquired immunodeficiency syndrome and organ transplantation in recent years. The proper recognition of CMV-infected cells in gastrointestinal mucosal biopsies is critical for effective treatment of this condition. METHODS: A total of 6580 endoscopic mucosal biopsies from 6323 patients in the 8-year period (1989-1996) were examined for CMV inclusion bodies. The endoscopic appearance and particularly the presence of ulcers were also analysed. RESULTS AND CONCLUSIONS: The prevalence of cytomegalovirus (CMV) inclusions was 9 per thousand in the gastrointestinal mucosal biopsies from an unselected group of patients. Of the 54 patients with CMV infection, 37 were immunocompromised and 17 apparently immunocompetent. Typical Cowdry inclusions and atypical inclusions were present, the latter more frequently in immunocompromised patients. The maximum prevalence of inclusions was in the oesophageal mucosa in immunocompromised individuals.

Endoscopic mucosal biopsies are useful in distinguishing granulomatous colitis due to Crohn's disease from tuberculosis.

BACKGROUND: Intestinal tuberculosis and Crohn's disease are chronic granulomatous disorders that are difficult to differentiate histologically. AIMS: To characterise distinctive diagnostic features of tuberculosis and Crohn's disease in mucosal biopsy specimens obtained at colonoscopy. METHODS: Selected histological parameters were evaluated retrospectively in a total of 61 biopsy sites from 20 patients with tuberculosis and 112 biopsy sites from 20 patients with Crohn's disease. The patients were chosen on the basis of clinical history, colonoscopic findings, diagnostic histology, and response to treatment. RESULTS: The histological parameters characteristic of tuberculosis were multiple (mean number of granulomas per section: 5.35), large (mean widest diameter: 193 microm), confluent granulomas often with caseating necrosis. Other features were ulcers lined by conglomerate epithelioid histiocytes and disproportionate submucosal inflammation. The features characteristic of Crohn's disease were infrequent (mean number of granulomas per section: 0.75), small (mean widest diameter: 95 microm) granulomas, microgranulomas (defined as poorly organised collections of epithelioid histiocytes), focally enhanced colitis, and a high prevalence of chronic inflammation, even in endoscopically normal appearing areas. CONCLUSIONS: The type and frequency of granulomas, presence or absence of ulcers lined by epithelioid histiocytes and microgranulomas, and the distribution of chronic inflammation have been identified as histological parameters that can be used to differentiate tuberculosis and Crohn's disease in mucosal biopsy specimens obtained at colonoscopy.

Diarrhoeal diseases.

Diarrhoea is a symptom of the response of the intestinal tract to a variety of primary diseases. It can be clinically classified based on the duration of the symptom and other associated features. In tropical regions, acute infective diarrhoea is widely prevalent and is an important factor contributing to morbidity and mortality, especially in children. The strategy of maintaining hydration by oral rehydration solutions has contributed significantly to reduction of mortality. Antibiotics are indicated only under specified circumstances. Persistent diarrhoea with prolonged symptoms increases the morbidity and mortality. Chronic diarrhoea is often associated with malabsorption of nutrients and an important component is tropical sprue, a primary malabsorption syndrome. Since diarrhoea is the response of the host to a variety of factors, the detailed study of this symptom has furthered the understanding of intestinal physiology.

Eosinophilic gastroenteritis--an Indian experience.

Eosinophilic gastroenteritis is an uncommon disorder with varied presentation. Records of 7 patients (6 men) with eosinophilic gastroenteritis, presenting to a large referral hospital over a 10-year period, were analyzed. The patients were young adults (mean age 32 years) with short duration (median 2 months) of illness. Symptoms included abdominal pain and vomiting (100%), weight loss (57%), diarrhea (43%) and abdominal distension (43%). Peripheral eosinophilia was present in all the patients. The diagnosis was made at duodenal (2 patients) or cecal (1) biopsy or surgical full-thickness jejunal biopsy (4). Three patients had predominantly mucosal disease (Klein type I), whereas two patients each had predominantly muscular (type II) and submucosal (type III) disease. Surgical resection was curative in one patient with type II disease. The other six responded to prednisolone, with complete resolution in one patient.

Salicylate inhibits fimbriae mediated HEp-2 cell adherence of and haemagglutination by enteroaggregative Escherichia coli.

Enteroaggregative Escherichia coli (EAggEC) are associated with both acute and persistent diarrhoea in children. Bowel colonisation due to fimbrial adherence factors appears to play a major role in the disease process. In this study, we investigated the effect of sodium salicylate and 5-aminosalicylic acid on adherence of a type strain and 40 clinical isolates of EAggEC to HEp-2 cells and erythrocytes from different species. Growth in the presence of 10 mM salicylate resulted in markedly decreased adherence to tissue culture cells with 33/40 (82.5%) isolates, and was also associated with inhibition of haemagglutination in 20/33 (60.6%) isolates. Complete or partial inhibition of adherence was also seen in two of five isolates showing localised adherence and three of five isolates with diffuse adherence. Decrease in adherence was associated with decreased or absent expression of fimbriae in 28/40 (70%) of the EAggEC isolates, although production of outer membrane proteins was not affected. Salicylates appear to inhibit adherence mediated by fimbrial adhesins.

Quantitative and ultrastructural analysis of rectal mucosal mast cells in acute infectious diarrhea.

The role of mast cells, potential mediators of mucosal immunity and inflammation, was studied morphologically in the rectal mucosa in two acute diarrheal diseases, cholera and shigellosis. Quantitation of mucosal mast cells showed that they were significantly higher in the deeper lamina propria where blood vessels and nerves were more abundant. There was no difference in mast cell counts or degranulation in the mucosa in both groups of patients and controls. Intraepithelial mast cells were decreased in the patients. The prevalence of lipid bodies was significantly higher in mast cells from patients with cholera and shigellosis (P < 0.01). These findings suggest that mast cell populations are more dense around blood vessels and nerves and that inflammatory mediators derived from arachidonic acid metabolites, as indicated by the lipid bodies, are the response of mast cells to the alterations in diarrhea, despite differences in the etiology of diarrhea.

Prevalence of intestinal parasites in rural Southern Indians.

OBJECTIVE: To determine the prevalence of intestinal protozoal and helminthic infection in a rural population. METHOD: Seventy-eight members of 15 families from a village were studied. Stool samples from all subjects were examined on alternate days for one month. RESULTS: The overall prevalence rate of various parasitic infections was 97.4%, with only 2 of 78 subjects not excreting parasites in any of their 15 samples. Eighteen (23.1%) persons had only one type of parasite, while 58 (74.3%) excreted multiple parasites. Giardia and Cryptosporidium were the commonest protozoan infections, affecting 42/78 (53.8%) and 31/78 (39.7%), respectively. Hookworm infestations were the commonest helminthic infections, seen in 48/78 (61.5%). Based on excretion patterns, the asymptomatic individuals could be divided into 2 groups of infrequent and frequent excretors, indicating that the host response may determine the level of parasite replication in the gut.

Immunoproliferative small intestinal disease in South India: a clinical and immunomorphological study.

Immunoproliferative small intestinal disease (IPSID), a proliferative disorder affecting the intestinal immune system, has only been reported sporadically in India. Fifteen patients with malabsorption syndrome who were diagnosed to have IPSID were included in this study. Mucosal biopsies from all patients, full thickness surgical biopsies from 10 and autopsy material from four patients were examined by light microscopy and immunohistochemistry. The patients were predominantly young (aged 16-36 years) and male (13 of 15). Diarrhoea, weight loss, vomiting and abdominal pain were the major symptoms. The upper small bowel was involved in all cases. Involvement of large bowel was detected antemortem in three patients, but was found in all autopsied patients. Involvement of the stomach was noted in one patient at autopsy. Mesenteric lymph nodes were involved in all patients who underwent laparotomy. The plasmacytic infiltrate was uniformly positive for alpha-heavy chain, and either negative for light chain production or showed monotypic light chain production. Some of the blasts were also positive for alpha-heavy chain. Three patients died before therapy could be commenced. One patient with stage A disease is alive and clinically free of disease at 7 years. Of the remainder, there have been four long-term survivors with chemotherapy. Immunoproliferative small intestinal disease occurs in southern India and has characteristics similar to that in other parts of the world. Early diagnosis may improve outcome in this disease.

Isolation of Vibrio cholerae O139 from the drinking water supply during an epidemic of cholera.

In mid-1994, the public water supply was investigated in a medium-sized town in south India during an epidemic of cholera due to Vibrio cholerae O139. Vibrio cholerae O139 was isolated from the public water supply including one of the wells supplying the town, the central overhead tank, and domestic taps connected to the public supply. Following chlorination, the organism was no longer isolated from the water supply and the epidemic subsided. This demonstration of V. cholerae O139 in the drinking water supply of a town underlines the need for adequate treatment of the water supply.

Evaluation of a simplified HEp-2 cell adherence assay for Escherichia coli isolated from south Indian children with acute diarrhea and controls.

A simplified HEp-2 cell adhesion assay was performed with stored Escherichia coli isolates from 761 children with acute diarrhea and 531 matched controls, and the results were evaluated by means of fluorescent actin staining and hybridization with DNA probes. The prevalence rates of localized adherence and aggregative adherence were significantly higher for patients (9.9 and 7.6%, respectively) than for controls (3.7 and 3.9%, respectively).

Ultrastructural changes in the upper small intestinal mucosa in patients with cholera.

BACKGROUND & AIMS: Small intestinal mucosal ultrastructural abnormalities were reported in a limited number of patients with cholera in the 1970s. This study extends these observations by examining distal duodenal biopsy samples from 19 patients with cholera and 10 controls. METHODS: Endoscopic biopsy samples obtained, usually during the first 24 hours of illness, were processed for electron microscopy. RESULTS: Widening of intercellular spaces and alteration of apical junctional complexes were prominent in the villus epithelium, whereas blebbing of microvillus border and mitochondrial changes were more prominent in the crypt epithelium. The apical junctional and intercellular space changes were not altered by oral rehydration. Degranulation of argentaffin cells, mucosal mast cells, and eosinophils; increase in neutrophil polymorphs; and changes in the enteric nerve fibers and microvasculature were also present. The extent of the changes correlated with clinical severity. CONCLUSIONS: The differential involvement of the villus and crypt suggests that factors responsible for secretion may act differentially on surface and crypt epithelium and that both regions may contribute to secretion. The contribution of the enteric nervous system, vasculature, argentaffin cells, mucosal mast cells, eosinophils, and neutrophils in the secretory process and in determining the severity of the clinical illness must be determined by further clinical studies.