Etiology of childhood diarrhea in Beijing, China.

To determine the role of recently recognized enteropathogens in childhood diarrhea in China, 221 children with diarrhea and 108 controls seen at the Beijing Children's Hospital were studied during April and May 1989. Stools were examined for ova, parasites, and rotavirus, cultured for bacterial pathogens, and probed for enterotoxigenic Escherichia coli (ETEC), enteroinvasive E. coli (EIEC), enterohemorrhagic E. coli (EHEC), and enteropathogenic adherence factor-positive (EAF+) E. coli. Pathogens were identified in 56.5% of children with diarrhea and 43.5% of controls (P = 0.04). Detection of enteropathogens was significantly greater in patients examined within 1 week of symptom onset (65%) than in patients examined later (39%; P = 0.01). ETEC was the most frequently detected pathogen in children with diarrhea, accounting for 20% of the cases. Other agents identified in patients included the following: salmonellae, 12%; rotavirus, 7%; EIEC, 7%; EHEC, 7%; members of the Aeromonas hydrophila group, 6%; EAF+ E. coli, 5%; Ascaris lumbricoides, 3%; shigellae, 3%; campylobacters, 2%; and Vibrio spp., 0.5%. The isolation rates of salmonellae (P = 0.02), EAF+ E. coli (P = 0.04), and mixed pathogens (P = 0.05) were significantly greater for diarrhea patients than for controls. Resistance to multiple antimicrobial agents occurred in 39% of the Salmonella isolates, 22% of the Aeromonas isolates, and 17% of the Shigella isolates. Multiresistant salmonellae (P = 0.05) and shigellae were recovered from diarrheal stools only. Ciprofloxacin, cefotaxime, and imipenem were the only agents tested to which all bacterial isolates were susceptible in vitro. These results suggest that both traditional and newly recognized agents are important causes of childhood diarrhea in Beijing and that therapy may be complicated by indigenous antimicrobial resistance.     

Case-Control Study of Enteropathogens Associated with Childhood Diarrhea in Dhaka, Bangladesh

The International Centre for Diarrhoeal Disease Research, Bangladesh, is a major center for research into diarrheal diseases. The center treats more than 100,000 patients a year. To obtain useful information representative of all patients, a surveillance system in which a 4% systematic sample of all patients is studied in detail, including etiological agents of diarrhea, was installed in October 1979. The first paper on etiology for the surveillance patients was published in 1982, which identified a potential enteric pathogen in 66% of patients. In subsequent years, several new agents of diarrhea have been identified. To assess the importance of a broader spectrum of diarrheal agents including the ones identified relatively recently, we studied 814 children with diarrhea. The children were up to 5 years of age and were part of the surveillance system. They were matched with an equal number of community controls without diarrhea. The study was conducted from February 1993 to June 1994. A potential enteric pathogen was isolated from 74.8% of diarrheal children and 43.9% of control children (P = 0.0001). Even though the first study was not a case-control study, it identified rotavirus, Campylobacter jejuni, enterotoxigenic Escherichia coli, Shigella spp. , and Vibrio cholerae O1 as major pathogens. The present study identified these pathogens as being significantly associated with diarrhea. In addition, the study also identified six additional agents, including enteropathogenic E. coli, Aeromonas spp., V. cholerae O139, enterotoxigenic Bacteroides fragilis, Clostridium difficile, and Cryptosporidium parvum, as being significantly associated with diarrhea. Plesiomonas shigelloides, Salmonella spp., diffusely adherent E. coli, enteroaggregative E. coli, Entamoeba histolytica, and Giardia lamblia were not significantly associated with diarrhea. Enteroinvasive E. coli, enterohemorrhagic E. coli, and Cyclospora cayetanensis were not detected in any of the children. The major burden of diseases due to most pathogens occurred in the first year of life. As in the previous study, seasonal patterns were seen for diarrhea associated with rotavirus, V. cholerae, and enterotoxigenic E. coli, and infections with multiple pathogens were common. With a few exceptions, these findings are in agreement with those from other developing countries. This knowledge of a broader spectrum of etiological agents of diarrhea in the surveillance patients will help us plan studies into various aspects of diarrheal diseases in this population.     

Two-year survey of etiologic agents of diarrheal disease at San Lazaro Hospital, Manila, Republic of the Philippines.

The prevalence of bacterial pathogens and rotavirus in 2,908 patients with diarrhea who were admitted to San Lazaro Hospital in Manila in 1983 and 1984 was determined. One or more enteric pathogens were isolated or detected in samples from 1,698 (58.4%) patients. Isolation rates for the various enteropathogens were as follows: rotavirus, 30.6%; Shigella spp., 11.6%; Salmonella spp., 9.2%; enterotoxigenic Escherichia coli (1983 only), 7.8%; Vibrio cholerae biotype eltor, 3.8%; non-O1 V. cholerae, 2.8%; Vibrio parahaemolyticus, 1.7%; other Vibrio spp., 1.1%; Campylobacter jejuni, 3.0%; Aeromonas hydrophila, 1.3%; and Plesiomonas shigelloides 1.1%. Giardia lamblia and Entamoeba histolytica were detected in 0.6 and 0.1%, respectively, of stool samples examined. Determination of the etiologic role of isolates was complicated by one or more of the following factors: isolation of multiple enteric pathogens (302 cases); isolation of Salmonella spp., enterotoxigenic E. coli, and C. jejuni from a similar proportion of asymptomatic control patients and patients with diarrhea; and isolation of a high proportion of certain pathogens (especially Salmonella spp.) only from enrichment broth, suggesting infection with a small number of organisms. Isolation of V. cholerae eltor was seasonal, with the majority of cases occurring in the rainy months. In addition, the number of patients with diarrhea increased with the onset of the monsoon rains and peaked during the months of maximum rainfall. Rotavirus infection occurred in both children and adults throughout the year and was the most frequently identified cause of diarrhea in children under 5 years of age. Shigella spp. were the most common agents of diarrhea in adults.     

Importance of salmonellae and Campylobacter jejuni in the etiology of diarrheal disease among children less than 5 years of age in a community in Bangkok, Thailand.

The etiology of diarrhea in children less than 5 years of age in a low-income housing project in Bangkok, Thailand, was determined over 1 year. Nontyphoidal salmonellae (13%), Campylobacter jejuni (12%), rotavirus (12%), enterotoxigenic Escherichia coli (7%), shigellae (6%), E. coli that hybridized with the enteropathogenic E. coli adherence factor probe (3%), and enteroinvasive E. coli (1%) were identified in 345 episodes of diarrhea in children less than 5 years of age. Salmonellae were identified in 17% and C. jejuni was identified in 15% of 54 children less than 6 months of age with diarrhea. Shigellae, enteroinvasive E. coli, enteropathogenic E. coli adherence factor, and enterotoxigenic E. coli were not isolated from children less than 6 months of age. Since salmonellae and C. jejuni were the most common bacterial pathogens identified in children less than 6 months of age, efforts to prevent transmission of salmonellae and campylobacter to young children should be a public health priority in Bangkok.     

High frequency of coinfecting enteropathogens in Aeromonas-associated diarrhea of hospitalized Peruvian infants.

Rectal swabs from 391 infants less than 18 months of age who were hospitalized with acute diarrhea and from 138 similarly aged healthy infants were examined for the etiologic agents of diarrhea. Aeromonas spp. were recovered from 205 of 391 (52.4%) diarrheic patients, whereas they were recovered from 12 of 138 (8.7%) controls (P less than 10(-11). Among the 205 Aeromonas-positive diarrheic patients, 118 (57.6%) were found to be coinfected with other common enteropathogens. Of the 164 Aeromonas-positive initial diarrheic specimens, 82 (50.0%) had one or more other enteropathogens present; 30 patients were coinfected with rotavirus, 20 with enterotoxigenic Escherichia coli, 16 with Campylobacter spp., 14 with Shigella spp., 13 with enteropathogenic E. coli, 4 with Vibrio spp., 1 with Salmonella spp., and 1 with Plesiomonas spp. of Aeromonas strains from cases compared with that from controls supports an etiologic role for this organism. However, frequent concomitant infections with other well-recognized enteropathogens and a lack of disease correlation with common Aeromonas phenotypes suggest that only a subset of Aeromonas strains may be diarrhea causing and that such strains may be common to several of the existing species.     

Enteroadherent Escherichia coli as a cause of diarrhea among children in Mexico.

Enteropathogenic Escherichia coli (EPEC) often exhibits localized adherence or diffuse adherence to HEp-2 cells. We recently provided evidence that HEp-2 cell-adherent or enteroadherent E. coli (EAEC) not belonging to EPEC serogroups was the cause of diarrhea among U.S. travelers to Mexico. In the present study, we looked for EAEC and EPEC in stool specimens from 154 children with acute diarrhea and 137 well children seen at several outpatient clinics in Guadalajara, Mexico. EAEC showing localized adherence (EAEC-L) was isolated from 13.0% of the patients and 0.7% of the controls (P less than 0.0001). EAEC showing diffuse adherence (EAEC-D) was recovered from 20.8% of the patients and 7.3% of the controls (P less than 0.001). EPEC was isolated from 4.5 and 6.7% of the patients and controls, respectively. Among all enteropathogens, only enterotoxigenic E. coli occurred as commonly (21.4%) as EAEC-D and EAEC-L did in children with diarrhea. Of the EAEC-L strains isolated from children with diarrhea, 20% belonged to recognized EPEC serogroups, and 3.1% of EAEC-D strains belonged to recognized EPEC serogroups. This study suggests that EAEC may be an important pediatric enteropathogen in Mexican children with diarrhea and further supports the observation that adherence to HEp-2 cells may be a marker of virulence independent of EPEC serogroup among E. coli strains.     

Epidemiology of bacterial pathogens associated with infectious diarrhea in Djibouti.

During a survey examining the causes of diarrhea in the East African country of Djibouti, 140 bacterial pathogens were recovered from 209 diarrheal and 100 control stools. The following pathogens were isolated at comparable frequencies from both diarrheal and control stools: enteroadherent Escherichia coli (EAEC) (10.6 versus 13%), enterotoxigenic E. coli (ETEC) (11 versus 10%), enteropathogenic E. coli (EPEC) (7.7 versus 12%), Salmonella spp. (2.9 versus 3%), and Campylobacter jejuni-C. coli (3.3 versus 5%). Surprisingly, the EAEC strains isolated did not correspond to well-recognized EPEC serogroups. No Yersinia spp., enteroinvasive E. coli, or enterohemorrhagic E. coli were isolated during the course of this study. Only the following two genera were recovered from diarrheal stools exclusively: Shigella spp. (7.7%) and Aeromonas hydrophila group organisms (3.3%). Shigella flexneri was the most common Shigella species isolated. Patients with Shigella species were of a higher average age than were controls (27 versus 13 years), while subjects with Campylobacter or Salmonella species belonged to younger age groups (2.6 and 1.6 years, respectively). Salmonella cases were more often in females. Shigella diarrhea was associated with fecal blood or mucus and leukocytes. ETEC was not associated with nausea or vomiting. Anorexia, weight loss, and fever were associated with the isolation of Salmonella and Aeromonas species. EAEC, ETEC, EPEC, and Shigella species were resistant to most drugs used for treating diarrhea in Africa, while the antibiotic most active against all bacteria tested was norfloxacin. We conclude that in Djibouti in 1989, Shigella and Aeromonas species must be considered as potential pathogens whenever they are isolated from diarrheal stools and that norfloxacin should be considered the drug of choice in adults for treating severe shigellosis and for diarrhea prophylaxis in travelers.     

Cohort study of Guinean children: incidence,pathogenicity, conferred protection,and attributable risk for enteropathogens during the first 2 years of life

We recruited 200 children shortly after birth and collected stool specimens weekly, irrespective of whether the children had diarrhea, until up to 2 years of age. All children were recruited during the first year of the study and were monitored for a median of 18.4 months. To measure pathogenicity, the odds ratio for diarrhea, adjusted for age, sex, and coinfections with other enteropathogens, was determined by logistic regression. Standard estimation of the population attributable risk indicated that rotavirus, enterotoxigenic Escherichia coli that produced only the heat-stable toxin ST, Isospora spp., Cryptosporidium parvum, Shiga toxin (Stx)-producing E. coli (STEC), and Shigella spp. or enteroinvasive E. coli were the most important contributors to diarrhea in this population. Stx2- but not Stx1-producing STEC strains were pathogenic. Enteroaggregative E. coli, diffusely adherent E. coli, and attaching-and-effacing E. coli strains, which were the most commonly isolated microorganisms, were not associated with diarrhea. For most of the microorganisms, primary infections did not confer protection against reinfection with the same organism, but some conferred protection against diarrhea from reinfection.     

Diarrhea caused by rotavirus in children less than 5 years of age in Hanoi, Vietnam

Group A rotaviruses are the major cause of diarrhea in young children worldwide. From March 2001 to April 2002, 836 children less than 5 years of age were investigated in Hanoi, Vietnam. This included 587 children with diarrhea and 249 age-matched controls. Group A rotavirus was identified in 46.7% of the children with diarrhea and 3.6% of the controls, which was a significant difference. Within the diarrhea group, the highest prevalence was seen in children from 13 to 24 months of age, and the prevalence was higher in males than in females. The symptoms of acute diarrhea caused by rotavirus were watery diarrhea, vomiting, fever, and dehydration. A higher prevalence of rotavirus detection was obtained for children who had all of these symptoms, followed by those who had diarrhea with vomiting-dehydration, fever-dehydration, and dehydration. The high rates occurred from September to December, although the infection was encountered all year round. In 58 patients (21.2% of the rotavirus-infected children), rotavirus infection was detected in association with either diarrheagenic Escherichia coli or Shigella spp. The most frequent combinations were rotavirus-enteroaggregative E. coli and rotavirus-enteropathogenic E. coli. At least one enteropathogen was identified from about 64% percent of the samples. The bacterial infection may not have given rise to clinical symptoms of such severity. The present study demonstrates the burden of rotavirus diarrhea in Hanoi, Vietnam. Continuous surveillance of diarrhea caused by rotavirus in young children would play an important role in diagnosis, treatment, and prophylaxis in order to improve the health of children in Vietnam.     

Parasitic, bacterial, and viral enteric pathogens associated with diarrhea in the Central African Republic.

A total of 1,197 diarrheic children less than 15 years old were investigated for parasitic, bacterial, and viral enteropathogens from March 1981 through February 1982 in the Central African Republic. One or more pathogens were identified from 49.4% of the patients. Rotavirus was the most frequently identified pathogen among children less than 18 months old. Enteropathogenic Escherichia coli was the second most frequently isolated pathogen (12.1%) in children less than 2 years of age. Campylobacter jejuni was also isolated frequently from diarrheic children less than 5 years of age (10.9%). Entamoeba histolytica was identified in very young children and was found to be the most frequent enteropathogen associated with diarrhea in children over the age of 2 years. Enterotoxigenic Escherichia coli was rarely isolated (ca. 2%). There was a peak in the incidence of rotavirus during the dry season and in the incidence of Campylobacter jejuni during the rainy season.     

Examination of colonies and stool blots for detection of enteropathogens by DNA hybridization with eight DNA probes

We compared three methods for detecting enteropathogens in 416 children with diarrhea: (i) examination of 10 lactose-fermenting and all non-lactose-fermenting Escherichia coli (colony blots); (ii) examination of 300 colonies (replicate blots); and (iii) determination of the total bacterial growth of stools (stool blots). All specimens were spotted onto Whatman 541 filters and hybridized with specific radiolabeled DNA probes. Enterotoxigenic E. coli was detected in 38 patients by examining colony blots, in 52 patients by examining replicate blots, and in 45 patients by examining stool blots. Enteropathogenic E. coli adhesin factor was detected in 12 patients by colony blots, in 25 patients by replicate blots, and in 16 patients by stool blots. E. coli that hybridized with the enterohemorrhagic E. coli probe was detected in 2 patients by colony blots, in 11 patients by replicate blots, and in 0 patients by stool blots. Shiga-like toxin-producing E. coli was detected in 0 patients by colony blots, in 12 patients by replicate blots, and in 0 patients by stool blots. Shigella spp. were identified by standard bacteriological methods in 82 patients, and enteroinvasive E. coli was identified by colony blots in 11 patients (total, 93), by replicate blots in 56 patients, and by stool blots in 35 patients. Of 82 culture-confirmed Shigella infections, 45 were identified by examining replicate blots with the 17-kilobase-pair probe and 36 were identified by examination with the Ipa probe (P less than 0.05). Examining replicate blots with specific probes identified more enterotoxigenic E.coli (P < 0.005), enteropathogenic E.coli adhesion factor-producing E.coli (P < 0.001), and Shiga-like toxin-producing E.coli (P < 0.005) infections than examining colony blots. More Shigella and enteroinvasive E.coli infections were identified by standard bacteriological methods and examining colony blots with a specific probe than by examining replicate and stool blots (P < 0.001).     

Prevalence of enteroaggregative Escherichia coli among children with and without diarrhea in Switzerland

In a prospective study between July 1999 and September 2000, stool specimens of children below the age of 16 years with (n = 187) and without (n = 137) diarrhea were tested for the presence of enterovirulent bacteria by standard culture methods and by PCR. Targets for the PCR were the plasmid pCVD432 for enteroaggregative Escherichia coli (EAEC), the verotoxin 1 and verotoxin 2 genes for enterohemorrhagic E. coli, ipaH for enteroinvasive E. coli (EIEC) and Shigella spp., genes coding for heat-stable and heat-labile toxins for enterotoxigenic E. coli (ETEC), and the eaeA gene for enteropathogenic E. coli. The following bacteria could be associated with diarrhea: Salmonella enterica (P = 0.001), Campylobacter spp. (P = 0.036), ETEC (P = 0.012), and EAEC (P = 0.006). The detection of EAEC, ETEC, and S. enterica was strongly associated with a history of recent travel outside of Switzerland. EAEC isolates were found in the specimens of 19 (10.2%) of 187 children with diarrhea and in those of 3 (2.2%) of 137 children without diarrhea (P = 0.006) and were the most frequently detected bacteria associated with diarrhea. Among the children below the age of 5 years, the specimens of 18 (11.9%) of 151 with diarrhea were positive for EAEC, while this agent was found in the specimens of 2 (2.2%) of 91 controls (P = 0.007). Enteropathogenic E. coli isolates were found in the specimens of 30 (16.4%) of the patients and in those of 15 (10.9%) of the controls, with similar frequencies in all age groups (P > 0.05). We conclude that EAEC bacteria are involved in a significant proportion of diarrhea cases among children. Children younger than 5 years of age are more often affected by EAEC than older children.     

Diffusely adherent Escherichia coli as a cause of acute diarrhea in young children in Northeast Brazil: a case-control study

In a prospective study carried out in two urban centers in northeastern Brazil, 195 HEp-2-adherent Escherichia coli strains were isolated; 110 were identified as the only pathogen in stools of children with diarrhea, and 85 were from controls. Enteropathogenic E. coli isolates were identified in 21 children with diarrhea (8.9%) and 7 children without diarrhea (3.0%), and they were significantly associated with diarrhea (P < 0.01). Enteroaggregative E. coli strains were isolated from 40 children with diarrhea (16.9%) and 38 children without diarrhea (16.4%) and showed no correlation with diarrhea (P > 0.5). In 49 children with diarrhea (20.7%) and 40 children without diarrhea (17.3%), diffusely adherent E. coli (DAEC) isolates were detected and were not found to be associated with diarrhea (P = 0.41). However, after stratification, for children older than 12 months of age a significant correlation between DAEC infection and diarrhea was detected (P = 0.01). These results suggest that DAEC isolates should be considered potential pathogens in northeastern Brazil and also confirm the association of DAEC with age-dependent diarrhea.     

Prospective study of diarrheal diseases in Venezuelan children to evaluate the efficacy of rhesus rotavirus vaccine

The efficacy of a rhesus rotavirus vaccine (MMU 18006, serotype 3) against infantile diarrhea was evaluated by active home surveillance of a group of 320 children 1-10 months of age in Caracas, Venezuela. During a 1 year period following oral administration of vaccine or placebo under a double-masked code, over 600 diarrheal episodes were detected. Etiologic studies revealed that heat-stable toxin (ST) producing enterotoxigenic E. coli (ETEC) was the most common diarrheal agent detected (34%) followed by enteropathogenic E. coli (EPEC, 10.9%), heat-labile toxin (LT) producing ETEC (7.6%), rotavirus (6.9%), Cryptosporidium (4.8%) and Campylobacter (1.3%). ST-producing ETEC were also recovered from over 20% of control stool specimens obtained during diarrhea-free periods, whereas EPEC, rotavirus, Cryptosporidium, and Campylobacter were rarely detected in such control specimens. Rotavirus was responsible for about one-half of the more severe cases of diarrhea. Twenty-two of 151 infants who received placebo (14.6%) and eight of 151 receiving a 10(4) PFU dose of vaccine (5.3%) had rotavirus diarrhea during the follow-up period for an efficacy level of 64% against any rotavirus diarrhea. However, vaccine efficacy reached 90% against the more severe cases of rotavirus diarrhea and was noticeably high in the 1-4 month age group. Serotypic analysis of the rotaviruses detected suggests that the resistance induced by the vaccine was type specific since significant protection was only evident against serotype 3 rotaviruses. A 10(3) PFU dose tested initially in 18 children did not appear to protect against rotavirus diarrhea.     

Role of the microbiology laboratory in the diagnosis of nosocomial diarrhea

Diarrhea that occurs in hospitalized patients is frequent and may be due to infectious or noninfectious causes. In adults with nosocomial diarrhea, the most commonly detected agent is Clostridium difficile; in children, rotaviruses are predominant. Various studies have shown that bacterial enteric pathogens (e.g. Salmonella spp., Shigella spp., Campylobacter spp...) or parasites are common causes of community-acquired diarrhea but rarely cause nosocomial enteritis. Stool cultures for these pathogens and ova and parasite examination should not be performed in patients hospitalized for more than three days unless there are plausible clinical or epidemiological reasons to do so. In contrast, C. difficile toxins assay (and rotavirus screening in children) should be primarily requested. The detection of C. difficile toxin B by stool cytotoxicity assay remains the 'gold standard'. Identification of toxin A (or A + B) can also be performed by immuno-enzymatic (ELISA) tests: results may be obtained in three hours. Electronic microscopy is the standard method for rotavirus diagnosis but tests using latex agglutination or immuno-enzymatic assay are now available. Various typing methods have been developed and may be routinely used in epidemiological investigations.     

Clinical manifestations of diarrhea in calves infected with rotavirus and enterotoxigenic Escherichia coli.

The susceptibility of gnotobiotic, colostrum-derived, or suckling calves to four bovine rotavirus isolates was found to be age dependent. Calves older than 7 days remained clinically normal, although they excreted virus in their feces and subsequently developed antibody against the virus, Enterotoxigenic Escherichia coli, fed to gnotobiotic, colostrum-deprived, or suckling calves ranging in age from a few hours to 26 days old, only caused diarrhea in animals younger than 24 h old. In contrast, diarrhea was consistently induced in 1- and 2-week-old calves infected with both enterotoxigenic E. coli and rotavirus. In general, diarrhea appeared after a rotavirus incubation period of approximately 3 days and was independent of the order in which the two microbial agents were given, the age of the calf, or the level of circulating rotavirus antibodies. The disease episode coincided with the excretion of rotavirus, rather than enterotoxigenic E. coli, in the feces. Infection with enterotoxigenic E. coli became established within 24 h of inoculation, and in older calves enterotoxigenic E. coli was often excreted in very small numbers and for a longer period than rotavirus.     

Noroviruses as a cause of traveler's diarrhea among students from the United States visiting Mexico

Stool specimens from 124 international travelers with acute diarrhea were tested for the presence of enteropathogens. Noroviruses (NoVs) were the second most commonly identified enteric pathogen in diarrheal stool samples (21/124, 17%), exceeded only by enterotoxigenic Escherichia coli (50/106, 47%). This study indicates that NoV is an underappreciated cause of traveler's diarrhea.     

Detection and characterization of diarrheagenic Escherichia coli from young children in Hanoi, Vietnam

Diarrhea continues to be one of the most common causes of morbidity and mortality among infants and children in developing countries. Escherichia coli is an emerging agent among pathogens that cause diarrhea. The development of a highly applicable technique for the detection of different categories of diarrheagenic E. coli is important. We have used multiplex PCR by combining eight primer pairs specific for enteroaggregative E. coli (EAEC), enteroinvasive E. coli (EIEC), enterohemorrhagic E. coli, enteropathogenic E. coli (EPEC), and enterotoxigenic E. coli (ETEC). This facilitates the identification of five different categories of diarrheagenic E. coli from stool samples in a single reaction simultaneously. The prevalences of diarrheagenic E. coli were 22.5 and 12% in the diarrhea group and the control group, respectively. Among 587 fecal samples from Vietnamese children under 5 years of age with diarrhea, this technique identified 132 diarrheagenic E. coli strains. This included 68 samples (11.6%) with EAEC, 12 samples (2.0%) with EIEC, 39 samples (6.6%) with EPEC, and 13 samples (2.2%) with ETEC. Among the 249 age-matched controls, 30 samples were positive for diarrheagenic E. coli. The distribution was 18 samples (7.2%) with EAEC, 11 samples (4.4%) with EPEC, and 1 sample (0.4%) with ETEC.     

Prevalence of diarrheagenic Escherichia coli in finns with or without diarrhea during a round-the-world trip

The incidence of diarrhea and the prevalence of bacterial enteropathogens, viruses, and parasites in feces of subjects with and without diarrhea were evaluated in 204 Finns traveling round the world (from Finland to China, Malaysia, Australia, Fiji, Chile, and Brazil and back to Finland). Special emphasis was placed on the finding of diarrheagenic Escherichia coli (enterotoxigenic, enteropathogenic, Shiga toxin-producing, and enteroaggregative strains) by PCR from growth on primary culture plates. From the PCR-positive samples, corresponding strains were isolated, confirmed as E. coli, and O serotyped. Of all the subjects, 37% experienced a total of 90 episodes of diarrhea. No adenoviruses or rotaviruses were detected, and findings of parasites were insignificant. In contrast, enteropathogenic bacteria were present in 62% of the 65 diarrheal and in 33% of the 127 nondiarrheal samples (P < 0.001); diarrheagenic E. coli strains were found in 35 and 26% of these, respectively (not statistically significant). As a single pathogen, E. coli was found in 20 and 24% of samples (not significant). Of all diarrheagenic E. coli strains, enteropathogenic strains were the most commonly found independently of the clinical picture of the subjects, whereas Salmonella enterica as a single pathogen was the most common non-E. coli organism found in diarrheal samples. Multiple bacterial pathogens were found 10 times more commonly in diarrheal than in nondiarrheal samples (20 versus 2%; P < 0.001).     

Relationships between rotavirus diarrhea and intestinal microflora establishment in conventional and gnotobiotic mice.

Intestinal microflora did not play a role in the intensity or course of EDIM rotavirus-induced diarrhea, since similar results were observed in axenic and conventional mice. In conventional mice, rotavirus-induced diarrhea did not modify the establishment of Lactobacillus spp. and Escherichia coli before weaning. The consequences of diarrhea on the establishment of strictly anaerobic bacteria after weaning were studied through the measurement of two bacterial functions, the microbial barrier effect against E. coli and the development of the immunoglobulin A intestinal immune system. These two bacterial functions were expressed in a similar way in diarrheic and control mice. In young gnotobiotic mice inoculated with Clostridium perfringens or C. difficile, rotavirus infection led to an earlier development of both strains, as compared with controls. This effect was more pronounced with C. difficile. These results suggest that rotavirus infections might enhance opportunistic bacterial infections.