Co-morbidity: exploring the clinical overlap between pneumonia and diarrhoea in a hospital in Dhaka, Bangladesh.

BACKGROUND: There is limited information on risk factors for pneumonia and pneumonia-related deaths in children who also have diarrhoea. AIM: To identify risk factors for the above in order to improve strategies for case management and to develop appropriate public health messages. METHODS: All children under 5 years of age admitted to the Special Care Ward, Dhaka Hospital of the International Centre for Diarrhoeal Disease Research (ICDDR,B) from 1 September to 31 December 2007 were considered for enrollment if they also had diarrhoea. Of the 258 children with diarrhoea enrolled, those with (n=198) or without (n=60) WHO-defined pneumonia constituted the pneumonia and comparison groups, respectively. Among the 198 children with pneumonia, children who survived (n=174) were compared with those who died in hospital (n=24). RESULTS: After adjusting for socio-demographic factors, including low levels of literacy of either parent, low household income, not having a window or exhaust fan in the kitchen, household smoking and over-crowding, children with pneumonia were more likely to sleep on a bare wooden-slatted or bamboo bed (OR 2·7, 95% CI 1·40-5·21, p = 0·003) than on other bedding, and were also more likely to have a parent/care-giver with poor knowledge of pneumonia (OR 1·94, 95% CI 1·02-3·70, p=0·043). Independent risk factors for death include severe underweight (OR 5·2, 95% CI 1·2-22·0, p=0·03), hypoxaemia (OR 17·5, 95% CI I 1·9-160·0, p=0·01), severe sepsis (OR 8·7, 95% CI I 1·8-41·5, p=0·007) and lobar consolidation (OR 11·9, 95% CI 2·3-61·6, p=0·003). CONCLUSIONS: Increased public awareness of signs of pneumonia and severe sepsis in children under 5 is important to mitigate the risks of pneumonia and pneumonia-related deaths, and the importance of appropriate bedding for young children in reducing the risk of pneumonia needs to be addressed.

Intestinal immune responses in patients infected with enterotoxigenic Escherichia coli and in vaccinees.

Immune responses against enterotoxigenic Escherichia coli (ETEC) were examined in Bangladeshi adults with naturally acquired disease and compared to responses in age-matched Bangladeshi volunteers who had been orally immunized with a vaccine consisting of inactivated ETEC bacteria expressing different colonization factor antigens (CFs) and the B subunit of cholera toxin. B-cell responses in duodenal biopsy samples, feces, intestinal washings, and blood were determined. Because most of the patients included in the study were infected with ETEC expressing CS5, immune responses to this CF were studied most extensively. Vaccinees and patients had comparable B-cell responses against this antigen in the duodenum: the median numbers of antibody-secreting cells (ASC) were 3,300 immunoglobulin A (IgA) ASC/10(7) mononuclear cells (MNC) in the patient group (n = 8) and 1,200 IgA ASC/10(7) MNC in the vaccinees (n = 13) (not a significant difference). Similarly, no statistically significant differences were seen in the levels of duodenal B cells directed against enterotoxin among vaccinees and patients. A comparison of the capacities of the various methods used to assess mucosal immune responses revealed a correlation between numbers of circulating B cells and antibody levels in saponin extracts of duodenal biopsy samples (r = 0.58; n = 13; P = 0.04) after vaccination. However, no correlation was seen between blood IgA ASC and duodenal IgA ASC after two doses of vaccine. Still, a correlation between numbers of CF-specific B cells in blood sampled from patients early during infection and numbers of duodenal B cells collected 1 week later was apparent (r = 0.70; n = 10; P = 0.03).

Astrovirus infection in association with acute, persistent and nosocomial diarrhea in Bangladesh.

BACKGROUND: Diarrhea is an important public health concern in developing countries such as Bangladesh. Diarrhea in children that persists for 14 days or more occurs in 7% of patients in Bangladesh and frequently results in death. Astrovirus has been demonstrated as a cause of acute and nosocomial diarrhea and can be excreted for prolonged periods, yet its importance as a cause of diarrhea among children in a developing country like Bangladesh has not been investigated. METHODS: We tested 629 stool specimens from patients with acute diarrhea, 153 from patients with persistent diarrhea, 175 specimens from 76 patients hospitalized for diarrhea who were sampled repeatedly to detect nosocomial infection and 428 from nonhospitalized healthy children (controls). All children enrolled in the study were <5 years of age. Astrovirus was detected by enzyme immunoassay and other enteropathogens were detected by standard techniques. RESULTS: The detection of astrovirus increased significantly with the duration of diarrhea. Astrovirus was found in 23 (15%) specimens from patients with persistent diarrhea, 26 (4%) patients with acute diarrhea, but only 8 (2%) healthy controls. This trend remained when we limited our analysis to infants <12 months of age and to episodes in which astrovirus was the sole pathogen. Among patients with nosocomial diarrhea, 16% of postadmission specimens were positive for astrovirus when the admission specimen was negative. CONCLUSION: The observation that astrovirus is detected more frequently with diarrhea of increasing duration suggests the need for further studies to determine whether astrovirus plays a causative role in persistent diarrhea or is a secondary agent.

Helicobacter pylori infection in infants and children of Bangladesh.

Helicobacter pylori is an important cause of chronic gastritis and plays important roles in the etiology of peptic ulcer disease, gastric cancer and non-ulcer dyspepsia. While H. pylori infections occur worldwide, the great majority of information is from the developed countries, and little is known about the epidemiology of H. pylori in the developing countries, particularly in children.

In situ characterization of inflammatory responses in the rectal mucosae of patients with shigellosis.

Shigella species cause bacillary dysentery in humans by invading epithelial cells of the colonic mucosa leading to colonic epithelial cell destruction and inflammation. For further analysis of local gut inflammation, morphological changes and the potential involvement of mediators in regulatory mechanisms of cell activation and cell proliferation were studied immunohistochemically in rectal mucosal biopsies taken from patients during the acute phase of shigellosis and at convalescence. Rectal biopsies from 25 Shigella dysenteriae-1 and 10 Shigella flexneri-infected patients and from 40 controls were studied. The frequencies of proliferative cells (Ki67-positive cells), p53-immunostaining cells, and cells coexpressing Ki67 with CD3 or with p53 were analyzed. Immunostaining for the inducible nitric oxide synthase (iNOS) and the endothelial NOS was assessed. In addition, the frequencies of apoptotic cells and CD68+ cells that engulf apoptotic cells were assessed. By morphological grading, 20% of the patients had advanced inflammation (grade 3) in the acute phase; mild inflammation (grade 1) was seen in 37% of the patients at convalescence as well as in 10% of the controls. The findings in the present study suggest that in the acute phase of shigellosis inflammation is characterized by increased cell turnover in the lamina propria (LP) and the epithelium, increased iNOS expression in the surface epithelium, and apoptosis, which seems to be associated with LP macrophages. The findings also suggest that neither p53 nor iNOS are important factors for the induction of apoptosis in shigellosis. Expression of p53 may be related to early cell activation in crypt epithelium. Moreover, there is an indication of an active, low-level inflammatory process at convalescence. The results thus indicate that Shigella-induced inflammation is associated with a complex series of cellular reactions in the rectal gut mucosa which persist long after clinical symptoms have resolved.

Shigella infection induces cellular activation of T and B cells and distinct species-related changes in peripheral blood lymphocyte subsets during the course of the disease.

Immunophenotypic changes in peripheral blood lymphocytes (T, B, and NK cells) in patients during shigellosis was characterized by using triple-color flow cytometry. Eleven Shigella dysenteriae 1-infected adult patients (SDIP), 11 Shigella flexneri-infected adult patients (SFIP), 15 age- and sex-matched healthy controls from Bangladesh (C-B), and 15 healthy volunteers from Sweden (V-S) were studied. In SDIP and SFIP, a significant increase in the CD45RO+ cells in both CD4+ and CD8+ T cells were seen. We found evidence for sequential T-cell activation, as shown by increased proportions of CD25 and CD4+ cells; HLA-DR and CD38 on CD8+ cells, and CD54 on CD4+ and CD8+ cells. We found differences in the lymphocyte activation and subset patterns related to the infecting Shigella species. Thus, a decrease in CD45 expression was seen in SFIP; this decrease progressed further during the disease. The proportions of NK cells (CD56+ cells) and CD3- CD8+ cells out of the total CD8+ cells were increased in SFIP but not in SDIP. The CD3+ CD8+ CD57+ T-cell subset was significantly lower in SDIP than in C-B. The proportion of B-lymphocyte-expressing activation markers CD80 and CD23 was higher in patients than in C-B. There was a significant increase in the proportion of CD4+ T cells and a significant decrease in the percentages of total B cells, the CD3+ CD8+ CD57+ T-cell subset, and the CD56+ CD16+ NK-cell subset for V-S compared with C-B. Our results indicate that distinct subset changes and activation patterns are elicited in SDIP compared with SFIP and also that the degree of activation is related to disease severity. In addition, a common sequence of cell activation was seen during the disease course. The difference in the subset patterns seen in C-B and V-S may be related to differences in the levels or spectra of infectious agents in the environment.

Down-regulation of gamma interferon, tumor necrosis factor type I, interleukin 1 (IL-1) type I, IL-3, IL-4, and transforming growth factor beta type I receptors at the local site during the acute phase of Shigella infection.

An immunohistochemical technique was used to examine whether there was a colocalization of cytokine-specific receptors with cytokine-expressing cells. We have previously shown that there is extensive cytokine production and secretion in the rectal mucosa in shigellosis (interleukin 1 alpha [IL-1 alpha], IL-1 beta, IL-1ra, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor alpha [TNF-alpha], TNF-beta, gamma interferon, granulocyte-macrophage colony-stimulating factor, and transforming growth factor beta [TGF-beta]) (R. Raqib, A. A. Lindberg, B. Wretlind, P. K. Bardhan, U. Andersson, and J. Andersson, Infect. Immun. 63:289-296, 1995; R. Raqib, B. Wretlind, J. Andersson, and A. A. Lindberg, J. Infect. Dis. 171:376-384, 1995). Kinetics for receptor expression was compared with that for cytokine synthesis in the inflamed rectal mucosa from Shigella-infected patients during acute (2 to 6 days after onset of diarrhea) and convalescent (30 to 40 days after onset) stages. Quantification of receptor expression was assessed by computer-assisted analysis of video microscopic images. A selective down-regulation of the receptors for gamma interferon, tumor necrosis factor (TNF receptor [TNFR] type I), IL-1 (IL-1 receptor [IL-1R] types I and type II), IL-3, IL-4, and TGF-beta (TGF-beta receptor type I) was observed at the onset of the disease, with a gradual reappearance during the convalescent stage. However, IL-2R, IL-6R, granulocyte-macrophage colony-stimulating factor receptor, TNFR type II, and TGF-beta receptor type II showed no change in expression during the study period and were comparable to controls. Cytokine receptors were predominantly located to the epithelial layer of the mucosal surface and crypts, with variable expression patterns in the lamina propria. A time-dependent kinetic curve was seen for the soluble IL-2R (sIL-2R), sIL-6R, and sTNFR types I and type II shed in stool at the acute stage similar to that observed for cytokine secretion in stool but at four- to six-times-lower concentration. In contrast, soluble receptor levels in plasma were 100-fold higher than the cytokine levels. The results suggest a dissociation in immune regulation between cytokine production and cytokine receptor expression. The down-regulation of the receptors in acute shigellosis was probably a consequence of cytokine-induced internalization and shedding of the receptors during signal transduction as well as due to programmed regulatory roles played by cytokines and the bacterial antigens.

Persistence of local cytokine production in shigellosis in acute and convalescent stages.

Shigella infection is accompanied by an intestinal activation of epithelial cells, T cells, and macrophages within the inflamed colonic mucosa. A prospective study was carried out to elucidate the cytokine pattern in Shigella infection linked to development of immunity and eradication of bacteria from the local site and also to correlate the cytokine profile with histological severity. An indirect immunohistochemical technique was used to determine the production and localization of various cytokines at the single-cell level in cryopreserved rectal biopsies from 24 patients with either Shigella dysenteriae type 1 (n = 18) or Shigella flexneri (n = 6) infection. The histopathological profile included presence of chronic inflammatory cells with or without neutrophils and microulcers in the lamina propria, crypt distortion, branching, and less frequently crypt abscesses. Patients had significantly higher (P < 0.005) numbers of cytokine producing cells for all of the cytokines studied, interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-1ra, tumor necrosis factor alpha (TNF-alpha), IL-6, IL-8, IL-4, IL-10, gamma interferon, TNF-beta, and transforming growth factor beta 1-3, in the biopsies than the healthy controls (n = 13). The cytokine production profile during the study period was dominated by IL-1 beta, transforming growth factor beta 1-3, IL-4, and IL-10. Significantly increased frequencies of cytokine-producing cells (P < 0.05) were observed for IL-1, IL-6, gamma interferon, and TNF-alpha in biopsies with severe inflammation in comparison with those with mild inflammation. During the acute stage of the disease, 20 of 24 patients exhibited acute inflammation in the rectal biopsies and the cellular infiltration was still extensive 30 days after the onset of diarrhea, although the disease was clinically resolved. In accordance with the histological findings, cytokine production was also upregulated during the convalescent phase; there was no significant difference (P > 0.05) in the incidence of cytokine-producing cells between acute (2 to 8 days after the onset of diarrhea) and convalescent (30 days after onset) stages.

Effects of tropisetron, a 5-hydroxytryptamine type 3 receptor blocker, on intestinal secretion induced by cholera toxin or deoxycholic acid in rabbits in vivo.

It has been suggested that 5-hydroxytryptamine is involved in the pathogenesis of various intestinal hypersecretory states including cholera. In this study, the effect of tropisetron (ICS 205-930), a specific 5-hydroxytryptamine type-3 receptor blocker, on jejunal and colonic fluid secretion induced respectively by cholera toxin and deoxycholic acid was investigated in rabbits using isolated loops of intestine in vivo. Marked fluid accumulation in both the jejunal and colonic loops was observed after exposure to cholera toxin and deoxycholic acid respectively. Elevation of jejunal and colonic mucosal cyclic adenosine monophosphate concentrations was also noted. Intraperitoneal administration of tropisetron dose-dependent inhibited jejunal secretion induced by cholera toxin. In contrast, no significant anti-secretory effect of tropisetron was observed against colonic secretion induced by deoxycholic acid. Tropisetron did not affect elevated mucosal cyclic adenosine monophosphate concentrations. The inhibitory effect of tropisetron on intestinal secretion induced by cholera toxin, which was independent of cyclic adenosine monophosphate formation, suggests that 5-hydroxytryptamine plays an important role in this type of secretion.

Diagnosis of bacterial overgrowth after culturing proximal small-bowel aspirate obtained during routine upper gastrointestinal endoscopy.

The purpose of this study was to evaluate the method of obtaining aspirated fluid for culture from the small intestine through a fiberoptic gastrointestinal endoscope for diagnosing small-bowel overgrowth. The study population consisted of 10 healthy volunteers and 26 patients with various gastrointestinal problems referred for routine endoscopic examination. The material to be cultured was obtained under direct visualization approximately 25 to 30 cm distal to the pylorus or from the afferent loop (in Billroth-II patients) with a sterilized sheathed wash pipe passed through the suction channel of the endoscope. Cultures were considered positive for bacterial overgrowth if total counts of organisms were 10(5)/ml or more. All healthy volunteers and 16 of 21 unoperated patients had sterile or insignificant growth, whereas all 5 patients who had Billroth-II operations had positive overgrowth. The endoscopic method for collection of proximal gastrointestinal fluid for culture is simple and can be performed during routine endoscopy.