Quantitation and properties of fecal and upper small intestinal aerobic microflora in infants and young children with persistent diarrhea

The duodenal juice and fecal aerobic microflora was investigated in 54 patients with persistent diarrhea (age less than or equal to 2 years). The duodenal aspirates yielded increased aerobic bacteria (greater than 10(5) organisms/ml) in 28 (51.9%) of the patients. Established enteric pathogens were isolated from the duodenal aspirates of 12 (22.2%) of the 54 patients, viz., enteroadherent Escherichia coli (EAEC) (5), enterotoxigenic E. coli (ETEC) (3), enteropathogenic E. coli (EPEC) (1), nontyphoidal Salmonella (1), and Giardia lamblia (2). The total aerobic bacterial count was greater than 10(5) in all 12 patients positive for specific pathogens apart from one case in whom E. coli showing diffuse adherence to HEp-2 cells were identified. Among the remaining 42 specific pathogen-negative patients, 19 (45.2%) also had greater than 10(5) aerobic organisms/ml in the small bowel. Eight strains of Klebsiella from four of the patients were negative for enterotoxin production in a rabbit ileal loop assay and for adherence to HEp-2 cells. In contrast, 28/54 (51.9%) of the same patients had known enteric pathogens in their stools, viz., nontyphoidal Salmonella (8 or 14.8%), Shigella (2 or 3.7%), Campylobacter (1 or 1.9%), ETEC (4 or 7.4%), EPEC (2 or 3.7%), EAEC (7 or 13.0%), and G. lamblia and Entameba histolytica (3 or 5.6%). Further search for potential virulence factors among aerobic bacteria colonizing the upper small intestine in persistent diarrhea is warranted.

Clinical significance of changes of flora in the upper digestive tract

Dysbiosis does not necessarily mean disease. Typical clinical picture of disease caused by metabolic activity of dysbiotic microflora is the microbial over-growth syndrome. We studied case histories of 434 patients without consideration of their basic illnesses and correlated them with types of dysbioses of duodenal juice. 55% of 314 patients with gastrointestinal disorders revealed a dysbiosis. A dysbiosis could also be found in up to 64% of pancreatic diseases, whereas intestinal dysfunctions and chronic inflammatory diseases usually show normal colonization. These cases express alteration of milieu conditions and disturbed interorganic connections. We only treated cases with objective pathological findings, obtaining best results with chemotherapeutic treatment of dysbioses with only one species.

Recent studies on the microbial ecology of the upper gastrointestinal tract

Microecological problems have escalated recently in clinical medicine. We studied the microecology of the upper small bowel. Duodenal flora was examined, displaying microbial growth in 90.8% of the 400 patients examined. The microflora was classified according to germ quality into definite types of colonization. Frequency of microbial colonization is normally 36.7% and 63.3% by overgrowth, indicating differing dysbioses. Simulation of microbial overgrowth in the duodenum is possible with a continuous-flow culture, demonstrating a biocenosis of several groups of micro-organisms with great metabolic activity. Continuous culture technique suggests possibilities for future studies of human gastrointestinal microecology.

Exocrine pancreatic function in patients with progressive systemic sclerosis

The exocrine pancreatic function was investigated in 16 patients with progressive systemic sclerosis by means of a meal test (Lundh test) and in 9 of the patients by the secretin-cholecystokinin test as well. Gastrointestinal involvement with progressive systemic sclerosis was evaluated by esophageal manometry and by routine roentgenographic series of the small bowel. Fecal fat excretion measurement, the D-xylose absorption test, and a small-intestinal biopsy procedure were carried out. Duodenal juice was cultured and bacterial counts were estimated. One-third of the patients had reduced exocrine pancreatic function, but only four patients had unequivocally a reduction that could be of clinical importance. The results obtained with the meal test were in accordance with the secretin-cholecystokinin test, indicating a preserved capacity for endogenous stimulation.

Bacterial growth and toxin production in ileostomy effluents

Escherichia coli (2), Vibrio cholerae (2) and Aeromonas sobria (1) strains were examined for their ability to grow and produce toxins in samples of ileostomy fluid. Three categories of response were observed: no detectable growth, growth without detectable toxin, and growth with detectable toxin. Clear differences were apparent between samples of ileostomy fluid obtained from different individuals and between samples obtained from the same individual at different times. The patterns of response were unique for each of the five test strains. We propose that the procedure developed forms a basis for investigating the host-parasite relationship in diarrhoeal disease.

Human immune response to Vibrio cholerae O1 whole cells and isolated outer membrane antigens

The serum immunoglobulin G (IgG) and mucosal secretory IgA (SIgA) response of human volunteers challenged with Vibrio cholerae O1 was analyzed for reactivity to V. cholerae O1 antigens by the immunoblot technique. Components of both in vitro- and in vivo (rabbit ligated ileal loop)-grown V. cholerae O1 were separated by sodium dodecyl sulfate-urea-polyacrylamide gel electrophoresis. Postchallenge serum IgG reacted uniquely with 15 antigens and with greater intensity than did prechallenge serum with at least 16 antigens. Serum IgG and SIgA reacted with antigens present in preparations from the homologous challenge strain of V. cholerae as well as antigens from strains of heterologous biotype or serotype. These heterologous antigens may represent antigens responsible for protection to rechallenge with a heterologous strain of V. cholerae. All the antigens detected by postchallenge jejunal fluid SIgA had an apparent molecular size of less than 25 kilodaltons. Serum IgG and jejunal fluid SIgA also reacted with antigens unique to in vivo-grown cells and several antigens in outer membrane preparations, suggesting that studies of protective immunity and V. cholerae O1 pathogenesis should include examination of both in vitro- and in vivo-grown V. cholerae O1 cellular antigens.

Campylobacter pylori in gastric, duodenal and jejunal juices and mucosae of patients with duodenal ulcer

The presence of Campylobacter pylori was investigated in biopsies and fluids obtained in the antrum, duodenal bulb and jejunum during jejunoscopy in 20 patients with an active duodenal ulcer. C. pylori was present in cultured antral biopsies in all patients, in the bulb of most patients (16/20), but was unusual in jejunal mucosa (2/20). Using a non-contaminated sampling method of fluid, C. pylori was found in only two samples at each level. In conclusion, C. pylori is frequent in bulbar mucosa of duodenal ulcer patients, rare in jejunal mucosa and in fluid at each level, thus confirming the ecological mucosal niche of C. pylori.

Abnormalities of the migrating motor complex in diabetics with autonomic neuropathy and diarrhea

Diarrhea is a common symptom in long-standing diabetes. The pathogenesis of this diarrhea remains obscure, although it appears to be related to the development of autonomic neuropathy, which may cause several abnormalities including altered gut motility. We studied fasting gastrointestinal motility for a mean of 210 min in a group of 12 type-II diabetics with diarrhea. All patients had peripheral neuropathy and symptoms of autonomic neuropathy. Their motor activity was compared with that of a group of six normal volunteers. In addition, gastrointestinal transit time was assessed by the hydrogen breath test. The presence of bacterial overgrowth was assessed by the hydrogen breath test and culture of jejunal secretions. The diabetics showed grossly disordered motor activity. There was a complete absence of phase-III activity in two patients. Most phase III's commenced in the distal duodenum or jejunum. The phase-III component was often of short duration at each recording site. There was increased velocity of propagation between sites. Continuous phase-II activity was noted in some patients. Antral activity was absent or reduced during phase II. Gastrointestinal transit time was significantly prolonged in the diabetics. Bacterial overgrowth was demonstrated in three diabetic subjects. These motility abnormalities are nonspecific and are unlikely to play a major role in the pathogenesis of diabetic diarrhea.

Microbial flora and bile acid metabolism in patients with an ileal reservoir

Bacterial flora of ileum effluent and bile acid metabolism were investigated in 11 patients 11-44 months after construction of a Kock's continent ileostomy. Bacteriologic investigation showed significantly more microorganisms per millilitre (p less than 0.01) and a more colon-like flora--that is, anaerobic microorganisms (p less than 0.001)--in ileum effluent of continent ileostomy patients than in ileum effluent of patients with a conventional ileostomy. The reabsorptive capacity of the reservoir mucosa was tested by direct introduction of a radioactively labelled conjugated bile acid, 23-75Se-25-homotaurocholic acid (SeHCAT), into the ileal pouch. After 4 h, 90% of the SeHCAT activity had been reabsorbed from the reservoir. Quantitative and differential analysis of bile acids in the ileum effluent showed unconjugated and predominantly primary (88%) bile acids, suggesting a minimal influence of bacterial flora on bile acid metabolism. Moreover, total bile acid loss appeared to be within normal limits.

Causes of malabsorption after total gastrectomy with Roux-en-Y reconstruction

Malabsorption after total gastrectomy and Roux-en-Y reconstruction was studied in 11 patients. Absorption of fat, xylose and lactose was tested and the orocaecal transit time was radiologically determined. Bacterial colonization of the small intestine was studied by culturing jejunal juice and indirectly with a hydrogen breath test. Ten patients lost weight postoperatively and six had diarrhoea. All 11 had steatorrhoea with mean faecal fat excretion 289 +/- 55 (SEM) mmol free and esterified fatty acids/72 h (upper reference limit 60 mmol/72 h). Low xylose absorption was found in only one patient and low lactose absorption in none. The median orocaecal transit time was only 110 minutes (less than or equal to 60 min in 4 cases). Postoperative weight loss showed significant inverse correlation with orocaecal transit time. Bacterial overgrowth of the small intestine was found in four patients. The cause of malabsorption was assumed to be rapid intestinal transit in four patients and bacterial overgrowth in four others, leaving three in whom pancreatic understimulation is suggested as the reason for steatorrhoea.

Volunteer studies of deletion mutants of Vibrio cholerae O1 prepared by recombinant techniques

Vibrio cholerae O1 A-B- vaccine strain JBK 70 and A-B+ CVD 101 prepared by recombinant DNA techniques from pathogenic EI Tor Inaba N16961 and classical Ogawa 395, respectively, were fed to 38 volunteers in single doses of 10(4) to 10(10). Although severe diarrhea did not occur in any vaccine, more than one-half developed mild diarrhea. These attenuated strains colonized well and elicited prominent vibriocidal and antitoxic (CVD 101) antibody responses. Recipients of a single dose of JBK 70 were significantly protected when challenged with 10(6) wild-type N16961. Diarrhea occurred in 7 of 8 controls but in only 1 of 10 vaccines (P less than 0.003, 89% vaccine efficacy), demonstrating the potency of immune mechanisms that do not involve cholera antitoxin. Further derivatives were prepared to explore the pathogenesis of the residual diarrhea, considering that either intestinal colonization by the vaccine itself or accessory toxins might be responsible. CVD 102, an auxotrophic mutant of CVD 101, did not cause diarrhea but colonized poorly and elicited feeble immune responses. Derivatives of JBK 70 and CVD 101 (CVD 104 and 105) deleted of genes encoding the EI Tor hemolysin still caused mild diarrhea. Genetically engineered strains can be colonizing, highly immunogenic, and protective single-dose oral vaccines, but they must be further attenuated before they can be considered for use as public health tools.

Diagnosis of bacterial overgrowth of the small intestine. Comparison of the 14C-D-xylose breath test and jejunal cultures in 60 patients

Sixty consecutive patients suspected of having bacterial overgrowth of the small intestine (BOG) had aerobic and anaerobic bacterial cultures made of fasting upper jejunal fluid and also a 14C-D-xylose breath test (XBT). Culture-proven BOG was present in 23 patients. In another 15 patients the presence of BOG was ruled out (diagnoses: irritable bowel syndrome, 8; chronic diarrhoea, 6; and lactose malabsorption, 1). These patients were used as controls. The other 22 of the 60 patients could not be placed in either group owing to the presence of factors known to predispose for BOG; none of them had abnormal jejunal cultures, but several had strong clinical suspicion of BOG. An abnormal XBT, defined as values exceeding upper 90% confidence limits (upper range) of the 15 patient control values within a 4-h period, was observed with the following frequencies in the 23 patients with BOG: after 60 min, 35%; after 120 min, 44%; after 180 min, 61%; and after 240 min, 65%. An abnormal XBT was observed in 41% of the 22 patients with normal jejunal cultures but with predisposition for, and clinical suspicion of, BOG. It is concluded that, compared with a relevant control material, the XBT tends to be rather insensitive and that a negative outcome of jejunal cultures is inadequate to exclude the presence of BOG.

Vibrio cholerae infection and acquired immunity in an adult rabbit model

We modified the rabbit model for enteric infection by Vibrio cholerae developed by Spira et al. and designated the RITARD (for removable intestinal tie-adult rabbit diarrhea) model (20). Our modification DISC comprises a permanent ligation of the cecum (C) to prevent resorption of the fluid secreted by the small intestine, a temporary ligation of the small intestine (S) to enable the bacteria to colonize, and duodenal inoculation (DI) of the challenge material. The main difference between RITARD and DISC is that in the latter model the challenge material is injected into the duodenum approximately 10 cm distal to the stomach instead of into the jejunum. Four out of 5 V. cholerae strains tested, including 2 serotypes and 2 biotypes, were able to elicit a massive and usually fatal cholera-like diarrhea. The virulence depended strongly on the culturing conditions. One strain, C5, caused fatal diarrhea in a dose of about 1000 organisms, even if the temporary ligation was omitted (DIC model). Other modifications were the DIS and the DI model in which the permanent ligature of the cecum or both ligatures were omitted. Duodenal inoculation of organisms in a dose of 100 X the minimum infective dose (MID) in the DIS or DI model did not cause any disease symptom. However, such inoculations were found to cause protection against subsequent challenges with 100 X MID of homologous and heterologous organisms up to 52 weeks after duodenal inoculation. Subcutaneous injection with classical, whole cell cholera vaccine gave only partial protection of short duration. This model might contribute to the understanding of the pathogenesis of cholera as well as to the improvement of efficacy testing of cholera vaccines.

Normal cultivable microflora in upper jejunal fluid in children without gastrointestinal disorders

Bacteriological studies of uncontaminated upper jejunal fluid were performed in 51 Danish children without gastrointestinal disorders. Thirty-seven percent of the samples were sterile [less than 10(1) colony-forming units (CFU)/ml]. In 25% of the cases, the total number of microorganisms exceeded 10(5) CFU/ml. The microorganisms isolated most frequently were: Streptococcus, sp. ("Viridans group"), Veillonella parvula, Hemophilus parainfluenzae, Lactobacillus, sp., Corynebacterium, sp., Actinomyces, sp., Bacteroides, sp., and Hemophilus influenzae, each found in more than 10% of the children. The upper range for the number of microorganisms isolated exceeded 10(5) CFU/ml for most of the species isolated of which the vast majority belonged to an "oral type" of flora. Enterococci were isolated in small numbers in three children, and Enterobacteriaceae were not found.

Short-chain fatty acids in the proximal gastrointestinal tract of healthy subjects

The total concentration of short-chain fatty acids (SCFAs) in healthy subjects, measured by gas chromatography, was in saliva and jejunal aspirates (n = 6) (median (range] 4480 (2780-9940) mumol/l and 265 (185-1470) mumol/l and in gastric and duodenal aspirates (n = 7) 719 (425-1770) mumol/l and 480 (137-778) mumol/l, respectively. Acetic and propionic acid accounted for 85% and 11%, respectively, and i-butyric, n-butyric, and i-valeric for less than 2% each in jejunal aspirates. A very similar relative distribution was present also in saliva and gastric and duodenal aspirates, essentially different from that of feces. Through anaerobic culturing from jejunum, 10(3) to 10(8) bacteria/ml was obtained; there was no correlation between the log number of bacteria and the SCFAs concentration before and after ingestion of sucrose. Swallowed exogenous radiolabeled propionate was partly recovered in the jejunum. The findings indicate that the SCFAs recovered from the jejunum in healthy subjects are mainly produced in the mouth and swallowed with the saliva.

Comparison between the bacterial and oligosaccharide content of ileostomy effluent in subjects taking diets rich in refined or unrefined carbohydrate

Dietary surveys have shown that patients with Crohn's disease tend to eat more sucrose than control subjects and this investigation was undertaken to determine whether a diet rich in refined carbohydrate affects the bacterial flora of the terminal ileum. Ileostomy effluent in five patients with Crohn's disease and five with ulcerative colitis after two weeks on a diet rich in sucrose and refined cereal has been compared with the same period on a diet low in sucrose and rich in unrefined cereal. Observations were made hourly for nine hours after equicaloric breakfasts representing the two diets. The amount of ileostomy effluent was greater on the unrefined carbohydrate diet both in terms of wet weight (238 +/- 89 g vs 162 +/- 79 g, p less than 0.02) and dry weight (23 X 6 +/- 6.8 g vs 14.9 +/- 6.6 g, p less than 0.01); surprisingly, the amount of glucose and oligosaccharide was also greater (169 +/- 41 mg vs 82 +/- 26 mg, p less than 0.001) in all 10 volunteers. The bacteriological flora per gram was also higher on the unrefined carbohydrate diet after the test meal (p less than 0.02 between three and six hours) as a result of a general increase in all organisms. The relative proportions of the organisms did not vary between the two diets. No differences were detected between patients with ulcerative colitis and those with Crohn's disease.

Enteropathogenicity of Klebsiella pneumoniae strains isolated from stools of diarrhoeal patients and other clinical specimens: an experimental study

In recent years strains of Klebsiella pneumoniae have been implicated as intestinal pathogen. Sixty three strains isolated from faeces of children with or without diarrhoea and other specimens of extraintestinal infections were tested for their enteropathogenicity in biological models. Thirty nine of them isolated from different sources caused accumulation of fluid in rabbit ileal loops comparable to that caused by toxigenic V. cholerae 569B. Ten strains, however, required 1-3 serial passages in rabbit gut before giving a positive loop reaction. Culture filtrates of these 39 strains also caused fluid accumulation comparable to that caused by live cells indicating elaboration of enterotoxic substance(s) in the medium. The enterotoxic factor was found to be heat-stable. However, the pattern of time course of fluid accumulation in ileal loops indicated elaboration of an additional heat labile factor. Most of the strains produced cytoxic factor as well. The mode of action of the toxin/s in secretion of fluid in experimental model possibly involve cAMP and prostaglandin. However, further studies are necessary to elucidate the exact mode of action of the enterotoxins. None of the strains tested was found to be enteroinvasive.

Biochemical changes in the jejunal mucosa of dogs with a naturally occurring enteropathy associated with bacterial overgrowth

The subcellular biochemical features of a naturally occurring enteropathy in the dog associated with bacterial overgrowth have been examined. Affected animals comprised a group of 10 German Shepherd dogs with raised serum folate and reduced vitamin B12 concentrations, mild steatorrhoea, reduced xylose absorption, and normal exocrine pancreatic function. Culture of duodenal juice showed bacterial overgrowth with mixed flora, most frequently including enterococci and Escherichia coli. Examination of peroral jejunal biopsies revealed predominantly minimal histological but distinct biochemical abnormalities in the mucosa. The specific activity of alkaline phosphatase was decreased, isopycnic density gradient centrifugation showing a marked loss particularly of the brush border component of enzyme activity. In contrast, gamma-glutamyl transferase activity was enhanced in brush border fragments of slightly increased modal density, but there were no changes in the activities of the carbohydrases, zinc-resistant alpha-glucosidase, maltase, sucrase, and lactase or of the peptidase, leucyl-2-naphthylamidase. Activities of lysosomal enzymes were increased and there was evidence for enhanced lysosomal fragility and mitochondrial disruption. The activities and density gradient distributions of marker enzymes for basal-lateral membranes, endoplasmic reticulum and peroxisomes were essentially unaltered. These findings show that bacterial colonisation of the proximal small intestine may be associated with specific alterations in microvillus membrane proteins and provide biochemical evidence for intracellular damage to the enterocytes.