Summer diarrhoea in African infants and children

Bacterial Factors Associated with Lethal Outcome of Enteropathogenic Escherichia coli Infection: Genomic Case-Control Studies

Background

Typical enteropathogenic Escherichia coli (tEPEC) strains were associated with mortality in the Global Enteric Multicenter Study (GEMS). Genetic differences in tEPEC strains could underlie some of the variability in clinical outcome.

Methods

We produced draft genome sequences of all available tEPEC strains from GEMS lethal infections (LIs) and of closely matched EPEC strains from GEMS subjects with non-lethal symptomatic infections (NSIs) and asymptomatic infections (AIs) to identify gene clusters (potential protein encoding sequences sharing ≥90% nucleotide sequence identity) associated with lethality.

Results

Among 14,412 gene clusters identified, the presence or absence of 392 was associated with clinical outcome. As expected, more gene clusters were associated with LI versus AI than LI versus NSI. The gene clusters more prevalent in strains from LI than those from NSI and AI included those encoding proteins involved in O-antigen biogenesis, while clusters encoding type 3 secretion effectors EspJ and OspB were among those more prevalent in strains from non-lethal infections. One gene cluster encoding a variant of an NleG ubiquitin ligase was associated with LI versus AI, while two other nleG clusters had the opposite association. Similar associations were found for two nleG gene clusters in an additional, larger sample of NSI and AI GEMS strains.

Conclusions

Particular genes are associated with lethal tEPEC infections. Further study of these factors holds potential to unravel the mechanisms underlying severe disease and to prevent adverse outcomes.

Typical enteropathogenic E. coli (tEPEC) strains are associated with high mortality among infants with moderate-to-severe diarrhea, but most infants infected with tEPEC strains survive, and some have no symptoms. To investigate the bacterial factors associated with severe outcome, we determined the genomic sequences of 70 EPEC strains. Twenty four tEPEC strains came from children with lethal infections. The prevalence of each gene was compared to that in strains from 23 matched infants who had non-lethal symptomatic infection and to that in 23 matched infants who had asymptomatic infection. We identified 392 genes associated with outcome, some of which were more prevalent in strains from lethal infections, while others were less prevalent. The genes included several encoding potential virulence factors such as type 3 secreted effectors and enzymes involved in O-antigen synthesis. A PCR assay validated the association of groups of alleles encoding variants of the NleG ubiquitin ligase with clinical outcome. Further study of the factors associated with severe outcome could lead to novel diagnostic, therapeutic and prevention strategies.

Socio-demographic, Clinical and Laboratory Features of Rotavirus Gastroenteritis in Children Treated in Pediatric Clinic

AIM

The aim of work was presentation of several socio-demographic, clinical and laboratory characteristics of gastroenteritis caused by rotavirus.

THE EXAMINEES AND METHODS

The examinees were children under the age of five years treated at the Pediatric Clinic due to acute gastroenteritis caused by rotavirus. Rotavirus is isolated by method chromatographic immunoassay by Cer Test Biotec.

RESULTS

From the total number of patients (850) suffering from acute gastroenteritis, feces test on bacteria, viruses. protozoa and fungi was positive in 425 (49.76%) cases. From this number the test on bacteria was positive in 248 (58.62%) cases, on viruses it was positive in 165 (39.0%), on protozoa in 9 (2.12%) cases and on fungi only one case. Rotavirus was the most frequent one in viral test, it was isolated in 142 (86.06%) cases, adenoviruses were found in 9 (5.45%) cases and noroviruses in only one case. The same feces sample that contained rotavirus and adenoviruses were isolated in five cases, whereas rotavirus with bacteria was isolated in the same feces sample in five cases. The biggest number of cases 62 (43.66%) were of the age 6-12 months, whereas the smallest number 10 (7.04%) cases were of the age 37-60 months. There were 76 (53.52%) of cases of male gender, from rural areas there were 81 (57.04%) cases and there were 58 (40.80%) cases during the summer period. Among the clinical symptoms the most prominent were diarrhea, vomiting, high temperature, whereas the different degree of dehydration were present in all cases (the most common one was moderate dehydration). The most frequent one was isonatremic dehydration in 91 (64.08%) cases, less frequent one was hypernatremic dehydration in 14 (9.85%) cases. The majority of cases (97.89%) had lower blood pH values, whereas 67 (47.17%) cases had pH values that varied from 7.16 -7.20 (curve peak), normal values were registered in only 3 (2.11%) cases. Urea values were increased in 45 (31.07%) cases (the maximum value was 26.5 mmol/L), whereas creatinine value was increased in 41 (28.87%) cases (maximum value was 302 mmol/L).

CONCLUSION

The results show the high frequency of rotavirus infections in children hospitalized with acute gastroenteritis. Rotavirus may cause different dehydration degree with electrolyte, acid-base and other biochemical disorders. Preventing the infection caused by rotavirus is of a great importance.

Polyethylene glycol diminishes pathological effects of Citrobacter rodentium infection by blocking bacterial attachment to the colonic epithelia

Infections from enteric bacteria such as enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic Escherichia coli (EHEC) are a public health threat worldwide. EPEC and EHEC are extracellular pathogens, and their interaction with host surface receptors is critical to the infection process. We previously demonstrated that polyethylene glycol (PEG) downregulates surface receptors in intestinal cells. Here we show that PEG decreases β1-integrin, the surface receptor in intestinal cells that is critical for EPEC and EHEC attachment. We hypothesized that PEG would inhibit the attachment of these enteric pathogens to host cells and improve clinical signs of infection. We found that attachment of the mouse enteric pathogen Citrobacter rodentium, which belongs to the same group of pathogens as EPEC and EHEC, was attenuated by the concurrent presence of PEG. Pretreatment with PEG, without concurrent presence during infection, also reduced bacterial attachment. This finding was further supported in vivo such as that PEG administered by gavage daily during infection as well as prior to infection significantly decreased C. rodentium in the colon and improved the appearance of the infected colon in mice. In addition, PEG decreased the β1-integrin in colonic mucosa and reduced the C. rodentium-induced activation of epidermal growth factor receptors. PEG also significantly reduced infection-induced colonic inflammation. Finally, PEG efficiently reduced C. rodentium shedding from the colon during infection. In conclusion, PEG can be an efficient and safe preventive agent against EPEC and EHEC infections.

The structures ofEscherichia coliO-polysaccharide antigens

Escherichia coli is usually a non-pathogenic member of the human colonic flora. However, certain strains have acquired virulence factors and may cause a variety of infections in humans and in animals. There are three clinical syndromes caused by E. coli: (i) sepsis/meningitis; (ii) urinary tract infection and (iii) diarrhoea. Furthermore the E. coli causing diarrhoea is divided into different 'pathotypes' depending on the type of disease, i.e. (i) enterotoxigenic; (ii) enteropathogenic; (iii) enteroinvasive; (iv) enterohaemorrhagic; (v) enteroaggregative and (vi) diffusely adherent. The serotyping of E. coli based on the somatic (O), flagellar (H) and capsular polysaccharide antigens (K) is used in epidemiology. The different antigens may be unique for a particular serogroup or antigenic determinants may be shared, resulting in cross-reactions with other serogroups of E. coli or even with other members of the family Enterobacteriacea. To establish the uniqueness of a particular serogroup or to identify the presence of common epitopes, a database of the structures of O-antigenic polysaccharides has been created. The E. coli database (ECODAB) contains structures, nuclear magnetic resonance chemical shifts and to some extent cross-reactivity relationships. All fields are searchable. A ranking is produced based on similarity, which facilitates rapid identification of strains that are difficult to serotype (if known) based on classical agglutinating methods. In addition, results pertinent to the biosynthesis of the repeating units of O-antigens are discussed. The ECODAB is accessible to the scientific community at http://www.casper.organ.su.se/ECODAB/.

A two-stage continuous culture system to study the effect of supplemental alpha-lactalbumin and glycomacropeptide on mixed cultures of human gut bacteria challenged with enteropathogenic Escherichia coli and Salmonella serotype Typhimurium

AIMS

Certain milk factors may promote the growth of a gastrointestinal microflora predominated by bifidobacteria and may aid in overcoming enteric infections. This may explain why breast-fed infants experience fewer intestinal infections than their formula-fed counterparts. The effect of formula supplementation with two such factors was investigated in this study.

METHODS AND RESULTS

Infant faecal specimens were used to ferment formulae supplemented with glycomacropeptide (GMP) and alpha-lactalbumin (alpha-la) in a two-stage compound continuous culture model. At steady state, all fermenter vessels were inoculated with 5 ml of 0.1 m phosphate-buffered saline (pH 7.2) containing 108 CFU ml-1 of either enteropathogenic Escherichia coli 2348/69 (O127:H6) or Salmonella serotype Typhimurium (DSMZ 5569). Bacteriology was determined by independent fluorescence in situ hybridization. Vessels that contained breast milk (BM), as well as alpha-la and GMP supplemented formula had stable total counts of bifidobacteria while lactobacilli increased significantly only in vessels with breast milk. Bacteroides, clostridia and E. coli decreased significantly in all three groups prior to pathogen addition. Escherichia coli counts decreased in vessels containing BM and alpha-la while Salmonella decreased significantly in all vessels containing BM, alpha-la and GMP. Acetate was the predominant acid.

SIGNIFICANCE AND IMPACT OF THE STUDY

Supplementation of infant formulae with appropriate milk proteins may be useful in mimicking the beneficial bacteriological effects of breast milk.

Anticipating rotavirus vaccines: epidemiology and surveillance of rotavirus in South Africa

Rotavirus infection is associated with acute infantile gastroenteritis in infants and young children globally. In South Africa, rotavirus infection has been shown to be associated with approximately one-quarter of all diarrhoeal admissions to hospital. Rotavirus infection predominantly occurs in infants less than 12 months of age (75%) and has a peak of shedding during the cooler, drier months of the year. A secondary peak during the spring has been observed. Multiple infections with rotavirus and at least one other microbial agent are common. The circulating VP7 serotypes and VP4 genotypes have been determined in various regions of South Africa and show a geographic specific distribution. A decade previously, P[8]G1 or G4 strains predominated, and P[4]G2 strains occurred in an epidemic pattern in one region. More recently, rotavirus strains with P[6] genotype have become common and novel VP7/VP4 genotype combinations are occurring across the country. G9 strains have been reported from Cape Town to Vendaland. The circulating rotavirus types observed in this study add to the knowledge of the natural history of rotavirus infection and provide the groundwork to consider future vaccine strategies.

Human milk fractions inhibit the adherence of diffusely adherent Escherichia coli (DAEC) and enteroaggregative E. coli (EAEC) to HeLa cells

Binding to a specific receptor is an essential step for most enteropathogens to initiate an intestinal infection. We analyzed the inhibitory effect of human milk and its protein components on adhesion of two diarrheagenic Escherichia coli strains, diffusely adherent E. coli (DAEC) and enteroaggregative E. coli (EAEC), to HeLa cells. Defatted milk, whey proteins, immunoglobulin and non-immunoglobulin fractions, in concentrations lower than usually found in whole milk, inhibited both DAEC and EAEC adhesion, indicating that human milk components may contribute to the defense of the infants against enteropathogens.

Managed care and public health departments: who is responsible for the health of the population?

This review examines changes over the past decade in the delivery of health care in the United States, specifically the move toward managed care and capitation. Over 77 million Americans are now enrolled in health maintenance organizations, and the health care delivery system is reorganizing into large group practices and integrated health systems. Examined here are the implications of this shift on the interaction between managed care and public health agencies. How will a population-based system of health care be achieved in light of managed care organizations' responsibility only for their enrolled population, in contrast to the responsibility of the public health service for the entire population? Where does the responsibility of MCOs end and that of public health begin? Should certain public health functions be absorbed by managed care organizations? What are the prospects for partnership between these two systems?

Epidemiology of rotavirus diarrhoea in Africa: a review to assess the need for rotavirus immunization

Rapid progress towards the development of rotavirus vaccines has prompted a reassessment of the disease burden of rotavirus diarrhoea in developing countries and the possible impact of these vaccines in reducing diarrhoeal morbidity and mortality among infants and young children. We examined the epidemiology and disease burden of rotavirus diarrhoea among hospitalized and clinic patients in African countries through a review of 43 published studies of the etiology of diarrhoea. The studies were carried out from 1975 through 1992, and only those in which a sample of more than 100 patients with diarrhoea were specifically screened for rotavirus by using an established diagnostic test were included. Rotavirus was detected in a median of 24% of children hospitalized for diarrhoea and in 23% who were treated as outpatients; 38% of the hospitalized patients with rotavirus were < 6 months and 81% were < 1 year of age. Rotavirus was detected year-round in nearly every country and generally exhibited distinct seasonal peaks during the dry months. In 5 countries where rotavirus strains had been G-typed, 74% of strains were of one of the four common serotypes (G1 to G4), G1 was the predominant serotype, and 26% were non-typeable. This cumulative experience from 15 African countries suggests that rotavirus is the most important cause of severe diarrhoea in African children and that most strains in circulation today belong to common G types that are included in reassortant vaccines. Wherever large numbers of cases of rotavirus diarrhoea occur early in infancy, immunization at birth may protect the children before their first symptomatic infection.

Effect of prior experimental human enteropathogenic Escherichia coli infection on illness following homologous and heterologous rechallenge

Two studies of adult volunteers were performed to determine whether prior enteropathogenic Escherichia coli (EPEC) infection confers protective immunity against rechallenge. In the first study, a naive control group and volunteers who had previously ingested an O55:H6 strain were fed an O127:H6 strain. In the second study, a control group and volunteers who had previously ingested either the O127:H6 strain or an isogenic eae deletion mutant of that strain were challenged with the homologous wild-type strain. There was no significant effect of prior infection on the incidence of diarrhea in either study. However, in the homologous-rechallenge study, disease was significantly milder in the group previously challenged with the wild-type strain. Disease severity was inversely correlated with the level of prechallenge serum immunoglobulin G against the O127 lipopolysaccharide. These studies indicate that prior EPEC infection can reduce disease severity upon homologous challenge. Further studies may require the development of new model systems.

Diarrheagenic Escherichia coli

Escherichia coli is the predominant nonpathogenic facultative flora of the human intestine. Some E. coli strains, however, have developed the ability to cause disease of the gastrointestinal, urinary, or central nervous system in even the most robust human hosts. Diarrheagenic strains of E. coli can be divided into at least six different categories with corresponding distinct pathogenic schemes. Taken together, these organisms probably represent the most common cause of pediatric diarrhea worldwide. Several distinct clinical syndromes accompany infection with diarrheagenic E. coli categories, including traveler's diarrhea (enterotoxigenic E. coli), hemorrhagic colitis and hemolytic-uremic syndrome (enterohemorrhagic E. coli), persistent diarrhea (enteroaggregative E. coli), and watery diarrhea of infants (entero-pathogenic E. coli). This review discusses the current level of understanding of the pathogenesis of the diarrheagenic E. coli strains and describes how their pathogenic schemes underlie the clinical manifestations, diagnostic approach, and epidemiologic investigation of these important pathogens.

Role of the eaeA gene in experimental enteropathogenic Escherichia coli infection

Enteropathogenic Escherichia coli (EPEC) infections are a leading cause of infant diarrhea in developing countries. Recently eaeA, a gene necessary for the characteristic intimate attachment of EPEC to epithelial cells in tissue culture, was described. We conducted a randomized, double-blind study to determine the role of the eaeA gene in human EPEC infection. 11 adult volunteers ingested 2 x 10(10) colony-forming units of O127:H6 EPEC strain E2348/69, and an equal number received the same dose of an isogenic eaeA deletion mutant constructed from E2348/69. Volunteers were monitored for the development of diarrhea, fever, and systemic and gastrointestinal complaints. Diarrhea developed in all 11 volunteers who received E2348/69 and in 4 of 11 who received the mutant (P = 0.002). Fever was more common in recipients of the wild-type strain (P = 0.024). Stool volumes were lower in recipients of the mutant. All volunteers seroconverted to E2348/69 LPS, but the geometric mean peak titers of serum IgG and IgA in recipients of the mutant were lower than those of recipients of the wild-type strain. IgA against LPS was detected in the jejunal fluid of six of six recipients of E2348/69 and 5/6 recipients of the mutant. This study unambiguously assigns a role for eaeA as an EPEC virulence gene, but the residual diarrhea seen in recipients of the mutant indicates that other factors are involved.

Diarrhoea caused by Escherichia coli

Since the mid-1940s, Escherichia coli has been recognized as a cause of diarrhoea. Subsequently it has been shown that at least five different pathogenic mechanisms are used to cause disease. Enterotoxigenic E. coli (ETEC) and enteropathogenic E. coli (EPEC) produce a noninflammatory diarrhoea, whereas enteroinvasive E. coli (EIEC), enterohaemorrhagic E. coli (EHEC) and enteroaggregative E. coli (EAggEC) produce an inflammatory diarrhoea. ETEC are a major cause of diarrhoea in infants (up to three episodes per year) and travellers. They produce diarrhoea by attaching to the small intestinal mucosa and elaborate one or both of heat labile and heat stable toxins. EPEC attach firmly to the intestinal mucosa leading to dissolution of the brush border by inducing vesiculation of the microvilli. This process is known as attaching-effacement, and in the jejunum and ileum results in a loss of brush border disaccharidase enzymes and a large area of absorptive surface. EPEC are a major cause of summer diarrhoea in infants and neonatal diarrhoea. EIEC attach to colonic enterocytes, penetrate by an endocytotic mechanism and replicate therein. This results in necrosis and stripping of large areas of colonic mucosa and a dysentery similar to but usually less severe than Shigella dysentery. EHEC produce attaching-effacement to the terminal ileal and colonic mucosa and release the toxins, verocytotoxin (VT) 1 or 2. These kill colonic enterocytes and produce haemorrhagic colitis. In addition, VT can damage vascular endothelial cells, leading to haemolytic uraemic syndrome. The role of EHEC in diarrhoea in children in the tropics is not known. The most recently described group are the EAggEC. They damage and blunt colonic villi by haemorrhagic necrosis, although the precise pathogenic mechanisms are unclear. EAggEC are a major cause of chronic diarrhoea in children. Although certain O-serotypes are associated with the different enteropathic E. coli, serotyping is not sufficiently specific or sensitive for use as a diagnostic tool. Specific diagnosis is expensive and time consuming and depends upon demonstration of the pathogenicity trait, and the pathogenicity gene(s) or their gene product(s). At present, to undertake such testing is not recommended for routine diagnosis but is most useful when surveys of the aetiology of acute and chronic diarrhoea are undertaken.

Enteropathogenic Escherichia coli

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Causative agents of acute diarrhoea in the first 3 years of life: hospital-based study

During the 2 years of the study, 402 patients and an equal number of age- and sex-matched controls were investigated for the presence of diarrhoeal pathogens. Pathogenic organisms were recovered from 277 (68.9%) patients and 97 (24.1%) controls. In the patient group, possible bacterial pathogens were found in 210 (52.2%) cases. Enteropathogenic Escherichia coli (EPEC) was the most frequently found potential pathogen, being recovered in 132 cases (32.8%) with serotypes 026, 086, 0111 and 0124 being the most frequently identified. Other bacterial pathogens identified were enterotoxigenic E. coli (ETEC) 57 (14.2%), Shigella 13 (3.2%) and Salmonella eight (2%). Rotavirus was identified in 33 (8.2%) cases. Mixed bacterial and viral infections were also seen in 26 (6.5%) cases. In the control group, enteric pathogens were recovered from 97 (24.1%) specimens. The most common bacterial pathogen found in this group was again EPEC (40, 9.9%), with serogroups 018, 044, 0111 and 0126 being the most frequent. Giardia lamblia and Entamoeba histolytica were found in 31 (7.7%) and 10 (2.5%) controls, respectively. Rotavirus was found in 16 (4%) controls. The results of both centres where the study was performed (Karachi and Rawalpindi) were compared.

Rotavirus studies in Indian (Asian) South African infants with acute gastro-enteritis: I. Microbiological and epidemiological aspects

This study, which is the first one documenting rotavirus (RV) diarrhoea in Asian infants in South Africa, describes the virological and epidemiological aspects of this disease in this population. Fifty-five per cent of 1142 hospitalized cases investigated over a 31-month period showed a positive stool ELISA for RV. Most of these children stopped shedding RV by days 4-6 of hospital admission, though prolonged excretion was recorded in some acute cases for up to 13 days. Mixed RV-bacterial infections occurred in 7% of the total gastro-enteritis (GE) patients, while 8.6% had pure bacterial gastro-enteritis. Sixteen per cent of 188 GE patients had serum anti-RV complement-fixing (CF) antibodies on admission. Rotavirus diarrhoea occurred in half of the seropositive infants. Seroconversion occurred in only two-thirds of the initially seronegative children who had RV diarrhoea. In 5.6% of the RV diarrhoea patients the infection was acquired nosocomially whilst in the hospital for other illnesses. The age-groups mainly affected were between 3 and 14 months, with a peak at 9-11 months; 3% of the RVGE patients were neonates. Both the RVGE and the total GE admissions showed well-marked winter peaks, with an inverse relationship between RV prevalence and both temperature and humidity. It is concluded that RV is the most important cause of infantile GE in this population, whereas pure bacterial infections play a relatively minor role. Circulating anti-RV antibodies do not necessarily afford protection against RV diarrhoea, probably owing to serotypic differences.

Aetiological factors of infantile diarrhoea: a community-based study

A community-based study was undertaken to compare the organisms responsible for diarrhoea in children living in formal housing with indoor water supply and sanitation with those from a deprived environment. The role of "home remedies" was also assessed. Among 373 children with diarrhoea, rotavirus was detected in 15% (in 371 symptom-free controls, 9%), and proved to be the single most common causative agent. Bacterial pathogens were found in 20% of patients, with enteropathogenic Escherichia coli (EPEC) being isolated most frequently (9%; controls 3%), followed by Shigella species (4%; controls 1%), Campylobacter jejuni (4%; controls 1%), Salmonella species (2%; controls 1%) and enterotoxigenic E. coli (ETEC) (2%; controls 1%). Giardia lamblia and cryptosporidium were detected in 6% (controls 6%) and 3% (controls 1%) of patients, respectively; 7% (controls 1%) harboured more than one enteropathogen and no pathogens were detected in 58% (controls 78%). The vast majority (greater than 90%) of both patients and controls received some form of "home remedy" which included disinfectants and traditional herbs. The findings of this study therefore confirm the extremely complex nature of diarrhoea in developing communities and indicate that environmental factors are compounded by other issues.

Serotype, antimicrobial resistance, and adherence properties of Escherichia coli strains associated with outbreaks of diarrheal illness in children in the United States

Since most recorded outbreaks of diarrhea in U.S. infants attributed to Escherichia coli occurred before currently available pathogenicity assays existed, we examined the characteristics of nonenterotoxigenic E. coli strains isolated from 50 outbreaks of diarrheal disease in U.S. infants between 1934 and 1987. We assayed the strains for enteropathogenic E. coli (EPEC) serotype, localized adherence (LA) and diffuse adherence to tissue cultures, the presence of EPEC adherence factor genes, Shiga-like (Vero) toxin production, and antimicrobial resistance. EPEC serotypes were identified in 28 outbreaks (56%). LA to HeLa cells was found in 23 outbreak strains and correlated 100% with the EPEC adherence factor probe. LA was observed in 21 of 28 EPEC and 2 of 22 non-EPEC strains; however, 5 of 23 strains that were LA positive for HeLa cells did not adhere to HEp-2 or HL cells. One strain was diffuse adherence positive, and none was Shiga-like toxin positive. Multiple resistance was common in EPEC (64%), LA-positive (74%), and LA-positive EPEC (76%) strains but not in others (10%). EPEC serotypes or LA was found in 60% (n = 30) of the outbreak strains. The remaining E. coli strains may represent nonpathogenic normal flora, as-yet-undefined pathogens, or pathogens that have lost virulence-associated traits during storage or subculturing.

Invasive potential of noncytotoxic enteropathogenic Escherichia coli in an in vitro Henle 407 cell model

The invasive capacity of 13 enteropathogenic Escherichia coli strains was assessed in vitro in Henle 407 cell culture. Both fluorescent microscopy of infected monolayers stained with acridine orange and electron microscopy revealed the presence of intracellular bacteria. As shown by acridine orange-stained infected monolayers, the number of internalized bacteria increased with time. Monolayers infected for 3 h were treated with antibiotics and either [14C]glutamine or [3H]leucine and incubated for various time intervals, after which the amount of radioactivity present in the washed monolayers was measured. A significant (P less than 0.005) increase in uptake was evident for up to 4 h after the addition of radiolabeled amino acid. This finding was confirmed by an increase in bacterial number in cultured cells and in protein concentration of infected cells with time. None of the South African enteropathogenic E. coli isolates used in these studies produced Vero cytotoxin. These findings demonstrate that, in addition to adherence, cell penetration and intracellular multiplication take place in epithelial cell-derived tissue culture cells infected by enteropathogenic E. coli.

Enteropathogens isolated from children with gastro-enteritis at Ga-Rankuwa Hospital, South Africa

A prospective 3-year study for enteric pathogens associated with diarrhoea in children was undertaken at Ga-Rankuwa Hospital, South Africa. Rotavirus was the most commonly isolated pathogen (24%), showing a marked seasonal distribution, with an autumn peak in activity. Enterotoxigenic and enteropathogenic Escherichia coli were frequently identified, and Salmonella, Shigella and Campylobacter were also isolated. Cryptosporidium and Giardia lamblia were the most frequently seen parasites. Rotavirus, E. coli, Salmonella and Campylobacter occurred predominantly in children less than 1 year old, whilst Shigella and the parasites were prevalent at all ages.

HeLa cell-adherent enteropathogenic Escherichia coli in children under 1 year of age in Thailand

Enteropathogenic Escherichia coli (EPEC) was isolated from 11% of 148 Hmong children under 1 year old with diarrhea at a refugee camp in northern Thailand. Of 16 children with EPEC-associated diarrhea, 11 were infected with EPEC that adhered to HeLa cells in a diffuse pattern, 3 were infected with EPEC that adhered to HeLa cells in a localized adherence (LA) pattern, and 2 were infected with EPEC that were nonadherent. In Bangkok, EPEC was isolated from 6% of 64 children under 1 year old with diarrhea and 7% of 56 children of the same age without diarrhea. Of four children with diarrhea, two were infected with EPEC with an LA pattern, and two were infected with nonadherent EPEC. Of four children without diarrhea, one was infected with EPEC with an LA pattern, one was infected with EPEC that adhered in a diffuse pattern, and two were infected with nonadherent EPEC. The 21 EPEC isolates with an LA pattern hybridized with the EPEC adherence factor DNA probe. EPEC was the only enteric pathogen identified in 16 (80%) of 20 children with EPEC-associated diarrhea. EPEC was as frequently isolated from children under 1 year old as were other bacterial enteric pathogens. The problem of identifying EPEC with pools of polyvalent antisera are described, and the need to identify additional enteropathogenic determinants of EPEC is discussed.

Cryptosporidiosis among black children in hospital in South Africa

Over a period of 3 months during the summer, 362 African children admitted to King Edward VIII Hospital, Durban, were screened for the faecal excretion of Cryptosporidium oocysts. Of 259 children with diarrhoea, oocysts were detected in 31 (11.9%), while none was found in the faeces of 103 children without diarrhoea (controls). All those children excreting Cryptosporidium were under 2 years of age, giving a prevalence of 15% for this group. Other potential enteric pathogens were detected in the faeces of 12 (38.7%) of these children. The case fatality rate for patients with Cryptosporidium was 22.6%, which may reflect the selection of patients in a study concentrating on hospital inpatients. Cryptosporidium was the second most common organism detected in diarrhoeal faeces, and the only one detected in 9.2% of diarrhoeal children aged less than two years. These findings indicate that Cryptosporidium should be regarded as a potential pathogen in children admitted to this hospital with severe diarrhoea. Such association of Cryptosporidium with diarrhoea in children accords with recent studies in other parts of the world.

Characterization of rotaviruses and subgroup F adenoviruses from acute summer gastroenteritis in South Africa

Six hundred and sixteen specimens were collected from black children hospitalised with acute gastroenteritis during the summer and autumn of 1982-1983 (October to May). Eighty-five children (13.8%) shed rotavirus and at least 40 (6.5%) shed adenovirus (Ad) type 40 or 41 belonging to subgroup F. The highest monthly prevalence of shedding subgroup F adenoviruses (10.1%) coincided with a peak in admissions in midsummer, whereas the highest monthly prevalence of shedding rotaviruses (41.9%) coincided with a peak in admissions in autumn. There were at least five genome types of rotavirus, at least three genome types of Ad40, and at least five genome types of Ad41 circulating in the Johannesburg-Soweto area during the study period. The high rate of rotavirus shedding in autumn could not be attributed to an upsurge in infections by any particular rotavirus strain.

Enteropathogenic Escherichia coli (EPEC) and enterotoxigenic (ETEC) related diarrhoeal disease in a neonatal unit

In an outbreak of summer diarrhoea in the neonatal unit, King Edward VIII Hospital, Durban, 25 (69%) of the 36 infants had organisms demonstrated in their stools. Four (11%) had EPEC alone, six (17%) ETEC alone, six (17%) EPEC plus rotavirus and nine (25%) all three organisms. Eleven (30%) infants had no organisms in their stools. Rotavirus alone was not present in any of the stools. Seven infants had septicaemia. The overall mortality was 22% and 62.5% of the deaths occurred in low birthweight infants. In a study of 41 infants without diarrhoea during the following winter and summer periods 55% of winter, 43% of summer controls, and four of 12 (33%) mothers had rotavirus. Only two (4.8%) of 41 infants had E. coli (EPEC). The findings suggest that E. coli (EPEC strain 044/K74[c], and ETEC) was the major cause of the outbreak and it was associated with a high mortality.

Aetiology of diarrhoea in adequately nourished young African children in Durban, South Africa

Two inter-related hospital-based studies on the causes of diarrhoea in African children who were not overtly malnourished, were performed over a period of two years in Durban, South Africa. The first study involved 126 inpatients selected for previously untreated diarrhoea of less than 96 h duration. On examination and culture of the stools of these children bacteria were identified in 60%, rotavirus in 20% and parasites in 4%. No pathogens were identified in 33%. The bacteria most frequently encountered were Campylobacter jejuni (21%), enteropathogenic Escherichia coli (EPEC) (18%), enterotoxigenic Escherichia coli (ETEC) (11%) and salmonella (8%). Of those cases having an identifiable cause 16% had more than one organism. The majority of children had mild disease and recovered clinically in 5.4 (1.3) days (Mean (s.d.]. The second study included 352 outpatients with diarrhoea who were randomly selected without regard to duration of disease or prior treatment. The results of faecal investigations were as follows: 28% had bacterial pathogens, 34% rotavirus, 15% parasites and 61% no pathogens. The bacteria most frequently detected were C. jejuni 7%, EPEC 7%, salmonella 6%, and shigella 5%. Ten per cent of positive cases had more than one pathogen. The most likely reason for the higher percentage with no identifiable pathogen is the prolonged duration of diarrhoea in 19% for more than seven days. In 128 control children with diarrhoea, stool samples were investigated during the same period as the two studies: 13% had bacteria, 2% rotavirus and 14% parasites. The bacteria involved were C. jejuni (5%). EPEC (5%), salmonella (2%) and shigella (2%).

Enteric infections, cow's milk intolerance and parenteral infections in 118 consecutive cases of acute diarrhoea in children

One hundred and eighteen consecutive cases of childhood acute diarrhoea (mean age: 10.5 months) were studied after admission to our Pediatric Unit in Naples over a 13-month period. A diagnosis was established in 92 patients (78%): 55% of patients were found to have an infectious enteritis (among them, 5 had ETEC infections and 1 had an ST-producing Klebsiella infection), 12% a parenteral infection, 11% cow's milk intolerance. The occurrence of gross blood (P less than 0.01), leukocytes, and reducing substances in the stools was more commonly associated with infectious enteritis than with diarrhoea due to all other causes. In 14 patients (8 of whom were malnourished), diarrhoea ran a prolonged course. In all, the eventual outcome was favourable. Our findings, while confirming that infectious enteritides account for most of acute diarrhoeas in children, stress the importance of parenteral infections and cow's milk intolerance in this condition. Also, the need for an accurate search for enterotoxigenicity of enterobacteria before ruling out their pathogenetic role is stressed.

Basic epidemiological aspects of acute gastro-enteritis in a regional hospital in Kuwait

Over a 12-month period 1045 children were hospitalized because of acute gastroenteritis. The disease accounted for 26% of admissions and for 20% of the total bed utilization. Prevalence peaked twice (autumn and spring), was low during summer and lowest in winter. Only 20% of children were breastfed on admission and in the great majority of those who were not, breast feeding was stopped under the age of two months. Early cessation of breast feeding may be responsible for the increased frequency of gastroenteritis in very young infants, and should be a cause for major concern in developing countries.

Age related susceptibility to Campylobacter jejuni infection in a high prevalance population

In a year long prospective study of diarrhoea in children under 2 years of age in Soweto, South Africa, Campylobacter jejuni was isolated in 18 of 60 children under 9 months of age with diarrhoea, compared with 4 of 60 age matched controls. In the older children, 16 of 51 children with diarrhoea and 17 of 51 control children excreted this organism in their faeces. These results indicate a change in susceptibility to C jejuni in children over 9 months of age. Campylobacter enteritis in the young children was usually mild, without macroscopic blood in the faeces, and prolonged excretion of the organism after acute attacks was not infrequent. Breast feeding did not seem to protect against colonisation with C jejuni.

Infections in children with severe protein-energy malnutrition

The infections occurring in 68 black children admitted to hospital with kwashiorkor, marasmus or marasmic-kwashiorkor were studied prospectively. Fifteen episodes of bacteraemia, most commonly due to Gram-negative enteric bacilli, occurred in 13 children (19%), six of these episodes being nosocomial. Urinary tract infection, diagnosed on suprapubic urine specimens and all due to Escherichia coli, occurred in five out of 16 cases (31%). In the 48 cases admitted with gastro-enteritis and 18 with pneumonia, a causative organism was found in the minority. Fifteen episodes of nosocomial infection occurred in 14 children (20.6%), of whom four died. Of the 14 deaths, eight were associated with bacteraemia. Skin infections were due mainly to staphylococci and streptococci. Infections in severely malnourished children appear to be due largely to the same microorganisms as cause infection in well-nourished children of the same community. Nosocomial infections pose a major threat to these children.

Enterotoxigenic Escherichia coli and other enteropathogens in paediatric diarrhoea in Addis Ababa

This study was performed during two weeks among 86 paediatric outpatients of poor socio-economic background. A control group comprised 60 healthy children. Enterotoxigenic Escherichia coli (ETEC) was the most common diarrhoeal agent isolated (26%). Strains of ETEC producing heat-labile (LT) only or LT and heat-stable (ST) enterotoxin were isolated from 11% each and ETEC producing ST only from 4% of the patients. ETEC was also found not infrequently among controls (10%). ETEC with O-antigens 78, 6 and 8 were shown to harbour colonization factors. Enterotoxigenic bacteria were found as contaminants in 5 of 24 feeding bottles investigated. Enteropathogenic Escherichia coli (EPEC) and Shigella species were isolated from 8% each and rotavirus from 24% of the patients. Twelve patients infected with ETEC only were compared to 66 patients not infected with ETEC. Patients infected with ETEC had a relatively mild disease and it was not possible by clinical findings to distinguish those patients infected with ETEC, LT and/or ST producing, carrying or not carrying colonization factors from those infected with other agents. This study underlines the need for extended studies of the clinical significance of ETEC infection in developing countries.

Variance in rotavirus infection rates in different urban population groups in South Africa

Rotavirus infection in black infants contrasts markedly with that of white infants in being much less common and showing no seasonal variation. In this multicentre study in Johannesburg, the aetiology of winter infantile gastroenteritis in black, coloured, and white infants was investigated. Stools were examined by electron microscopy and also by enzyme-immunoassay to detect subparticular antigen which may be missed by electron microscopy in patients presenting late in the course of the illness. Stools were also examined bacteriologically by conventional techniques. Rotavirus was the most common pathogen in all three population groups with bacteria playing a relatively minor role. Striking differences were observed in the rotavirus rates between the three groups. Infection in the whites was five times more common than in the blacks (60% versus 12%) with the coloureds intermediate at 40%. The hypothesis was put forward that the relative protection of the black population may be due to a greater degree of colonization of neonates, thus inducing protection against symptomatic infection at the target age of 6 to 24 months. This may well have important implications in immunoprophylaxis. The reason for the lack of seasonal variation in the black population is still unclear.

Gastroenteritis among children in Riyadh: a prospective analysis of 254 hospital admissions

A prospective study was undertaken of 254 infants and children admitted with gastroenteritis to the Children's Hospital, Riyadh, Saudi Arabia during the period 1 September 1980 to 1 February 1981. Analysis of data showed that 80% of the admissions were less than one year of age. The peak incidence occurred in the 0-five months age group. 65.4% were on bottle feeding. The incidence of second- and third-degree malnutrition was 38.9%. Marasmus was the commonest type of severe malnutrition seen. Hypernatraemic dehydration occurred in 12.6% of the cases. The parasitic and bacterial isolation rate was 23.8%, salmonella and entero-pathogenic E. coli being the commonest organisms. The mortality rate was 9.1% and was higher among malnourished patients, those with hypernatraemia and in the younger age groups.