Prevalence of diarrheogenic Escherichia coli and rotavirus among children from Botucatu, São Paulo State, Brazil

Modelling rotavirus concentrations in rivers: Assessing Uganda's present and future microbial water quality

Faecal pathogens can be introduced into surface water through open defecation, illegal disposal and inadequate treatment of faecal sludge and wastewater. Despite sanitation improvements, poor countries are progressing slowly towards the United Nation's Sustainable Development Goal 6 by 2030. Sanitation-associated pathogenic contamination of surface waters impacted by future population growth, urbanization and climate change receive limited attention. Therefore, a model simulating human rotavirus river inputs and concentrations was developed combining population density, sanitation coverage, rotavirus incidence, wastewater treatment and environmental survival data, and applied to Uganda. Complementary surface runoff and river discharge data were used to produce spatially explicit rotavirus outputs for the year 2015 and for two scenarios in 2050. Urban open defecation contributed 87%, sewers 9% and illegal faecal sludge disposal 3% to the annual 15.6 log₁₀ rotavirus river inputs in 2015. Monthly concentrations fell between -3.7 (Q5) and 2.6 (Q95) log₁₀ particles per litre, with 1.0 and 2.0 median and mean log₁₀ particles per litre, respectively. Spatially explicit outputs on 0.0833 × 0.0833° grids revealed hotspots as densely populated urban areas. Future population growth, urbanization and poor sanitation were stronger drivers of rotavirus concentrations in rivers than climate change. The model and scenario analysis can be applied to other locations.

Present and Future Human Emissions of Rotavirus and Escherichia coli to Uganda's Surface Waters

Rotavirus (RV) and diarrheagenic are waterborne pathogens commonly causing diarrhea in children below five years old worldwide. Our study is a first step toward a loads-concentrations-risk modeling and scenario analysis framework. We analyzed current and future human RV and indicator (EC) emissions from sanitation facilities to surface waters in Uganda using two process-based models. Emissions were estimated for the baseline year 2015 and for three scenarios in 2030 using population, excretion rates, sanitation types, and wastewater treatment. The first model is a downscaled GloWPa-Rota H1 version, producing emissions at a 1-km resolution. The second model is newly developed for Kampala and adds emissions from pit latrines and septic tanks excluded in the first model. The scenarios Business as Usual, Industrious, and Low Emissions reflect government prospects in sanitation coverage and wastewater treatment. For the first model, 6.14 × 10 RV particles d and 1.31 × 10 EC colony-forming units (CFU) d are emitted to surface waters in 2015. The RV emissions are expected to increase in 2030 by 75% for Business as Usual and 212% for Industrious and decrease by 58% in Low Emissions. Emissions from the second model are higher for Kampala than in the first model, at 3.74 × 10 vs. 5.95 × 10 RV particles d and 8.18 × 10 vs. 1.75 × 10 EC CFU d in 2015, most of which come from the onsite-not-contained category. Simulated emissions for Kampala show the importance of including onsite sanitation in our modeling. Our study is replicable in other locations and helps identify key emission sources, their hotspots, and the importance of wastewater treatment. The scenarios can guide future sanitation safety planning.

Cytolethal distending toxin-producing Escherichia coli strains causing severe diarrhoea in young Mexican children

Introduction. Cytolethal distending toxins (CDTs), encoded by cdt genes, have DNase activity leading to cellular and nuclear distension, resulting in irreversible cell cycle arrest and apoptosis of target cells. cdt-positive Escherichia coli strains have been isolated from children with diarrhoea. There is, however, scant information on the prevalence and clinical presentation of diarrhoeal disease caused by these strains. Furthermore, toxin production of cdt-positive strains is rarely confirmed. We report five young children with diarrhoea caused by CDT-producing E. coli in whom stools were negative for other bacterial or enteric pathogens.

Case presentation. On admission to hospital, all children presented watery diarrhoea with high stool output (range 7–20 stools/24 h); five had fever of 38 °C or more and four presented vomiting. Dehydration was present in four patients, one of whom had hypovolaemic shock; one child also presented hyponatraemia and hypokalaemia. In two children, cdt-positive strains were classified as typical and atypical enteropathogenic E. coli, and the remaining three harboured cdt-positive strains that did not belong to any diarrhoeagenic pathogroup. One cdt-positive strain from each case was characterized by a CDT cytotoxic assay and a cdt type-specific PCR. All strains produced the characteristic cellular intoxication due to CDT. Two strains carried the cdt-I, one cdt-III, one cdt-IV, and one concurrently had cdt-I, cdt-II and cdt-III genes.

Conclusion. Our results suggest that CDT-producing E. coli strains are an infrequent, albeit significant, cause of severe diarrhoeal illness in children. Future research should measure the true burden of cdt-positive E. coli diarrhoea among children.

Global seasonality of rotavirus disease

BACKGROUND

A substantial number of surveillance studies have documented rotavirus prevalence among children admitted for dehydrating diarrhea. We sought to establish global seasonal patterns of rotavirus disease before the introduction of widespread vaccination.

METHODS

We reviewed studies of rotavirus detection in children with diarrhea published since 1995. We assessed potential relationships between seasonal prevalence and locality by plotting the average monthly proportion of diarrhea cases positive for rotavirus according to geography, country development and latitude. We used linear regression to identify variables that were potentially associated with the seasonal intensity of rotavirus.

RESULTS

Among a total of 99 studies representing all 6 geographic regions of the world, patterns of year-round disease were more evident in low- and low-middle income countries compared with upper-middle and high-income countries where disease was more likely to be seasonal. The level of country development was a stronger predictor of strength of seasonality (P = 0.001) than geographic location or climate. However, the observation of distinctly different seasonal patterns of rotavirus disease in some countries with similar geographic location, climate and level of development indicate that a single unifying explanation for variation in seasonality of rotavirus disease is unlikely.

CONCLUSION

While no unifying explanation emerged for varying rotavirus seasonality globally, the country income level was somewhat more predictive of the likelihood of having seasonal disease than other factors. Future evaluation of the effect of rotavirus vaccination on seasonal patterns of disease in different settings may help understand factors that drive the global seasonality of rotavirus disease.

Prevalence of Multiple Drug Resistant Escherichia coli Serotypes in a Tropical Estuary, India

A total of eighty-one Escherichia coli isolates belongs to forty-three different serotypes including several pathogenic strains such as enterotoxigenic E. coli (ETEC), enterohaemorrhagic E. coli (EHEC), enteropathogenic E. coli (EPEC) and uropathogenic E. coli (UPEC) isolated from a tropical estuary were tested against 12 antibiotics to determine the prevalence of multiple antibiotic resistance (MAR), antimicrobial resistance profiles and also to find out high risk source of contamination by MAR indexing. The results revealed that more than 95% of the isolates were multiple antibiotic resistant (resistant to more than three antibiotics). Resistance to vancomycin, novobiocin, kanamycin, oxytetracycline, tetracycline, streptomycin was high (>80%), resistance to other antibiotics was relatively less. The MAR indexing of the isolates showed that all these strains were originated from high risk source of contamination. The incidence of multiple antibiotic resistant E. coli especially the pathogenic strains in natural water will pose a serious health risk to the human population and also act as a `manmade' reservoir of resistance genes for (potentially) pathogenic bacteria. The determination of antibiotic susceptibility/resistance patterns of isolated microbes is a part of the microbial monitoring process of the water which would be important for the meaningful interpretation of sanitary water quality data.

Pathotypes of diarrheagenic Escherichia coli in children attending a tertiary care hospital in South India

The prevalence of diarrheagenic Escherichia coli (DEC) in children under 5 years was studied in children with diarrhea and controls in South India. Four polymerase chain reaction (PCR) "schemes" were used to detect genes of the 6 pathotypes of DEC. In 394 children with diarrhea, 203 (52%) DEC infections were found. Among the 198 controls, 126 (63%) DEC infections were found. Enteroaggregative E. coli was the most common pathotype by multiplex PCR both in cases (58, 14.7%) and controls (47, 23.7%), followed by enteropathogenic E. coli seen in 10% cases and 8% of controls. Enterotoxigenic E. coli (ETEC), enterohemorrhagic E. coli (EHEC), enteroinvasive E. coli (EIEC), and diffusely adherent E. coli (DAEC) were found in 4.1%, 2.0%, 1.0%, and 0.5% of cases, respectively. ETEC was found in 2.5% of controls, but EHEC, EIEC, and DAEC were not detected. Overall, no single assay worked well, but by discounting genes with a pathogenicity index of less than 1, it was possible to use the PCR assays to identify DEC in 75/394 (19%) cases and 12/198 (6.1%) controls, while mixed infection could be identified in 8/394 (2%) cases and 2/198 (1%) controls.

Investigation of diarrhea agents less than 5 years of age in summer in Gaziantep/Turkey

Pathogens causing summer diarrhea examined to detect among children less than 5 years of age in Gaziantep. We conducted among 100 children with diarrhea during summer at the pediatric hospital of Gaziantep. In stool samples from children, Rotavirus with Rotatect kit (Dade Behring, Germany), Entamoeba spp. with direct microscopy and bacterial pathogens with cultural techniques investigated. Cystic form of Entamoeba spp. was determined in 61 (61%) and Rotavirus antigen in 25 positive samples (25%). A predominant bacterium was determined in total 87 stool samples (87%). Despite of only cystic form of Entamoeba spp. was determined in seven, only bacteria in 22 and only Rotavirus in one; two of them were determined in 67 out of stool samples. According to comparison with stool samples belong to various months we have found that, Rotavirus and E. coli are the most pathogenic agents in August more than June and July.

Typical enteroaggregative and atypical enteropathogenic types of Escherichia coli are the most prevalent diarrhea-associated pathotypes among Brazilian children

A 1-year prospective study was carried out in two large urban centers of São Paulo State, Brazil, to determine the prevalences and roles of the different Escherichia coli pathotypes in children less than 5 years of age with diarrhea presenting to the emergency rooms of public hospitals or visiting private pediatricians' offices. Of the pathotypes sought, typical enteroaggregative and atypical enteropathogenic types of E. coli were isolated for 8.9% and 5.4% of 774 diarrhea cases, respectively, and were found to be dominant and significantly associated with diarrhea.

Etiology and epidemiology of diarrhea in children in Hanoi, Vietnam

OBJECTIVES

This paper provides a preliminary picture of diarrhea with regards to etiology, clinical symptoms, and some related epidemiologic factors in children less than five years of age living in Hanoi, Vietnam.

METHODS

The study population included 587 children with diarrhea and 249 age-matched healthy controls. The identification of pathogens was carried out by the conventional methods in combination with ELISA, immunoseparation, and PCR. The antibiotic susceptibility was determined by MIC following the NCCLS recommendations.

RESULTS

Of those with diarrhea, 40.9% were less than one year old and 71.0% were less than two years old. A potential pathogen was identified in 67.3% of children with diarrhea. They were group A rotavirus, diarrheagenic Escherichia coli, Shigella spp, and enterotoxigenic Bacteroides fragilis, with prevalences of 46.7%, 22.5%, 4.7%, and 7.3%, respectively. No Salmonella spp or Vibrio cholerae were isolated. Rotavirus and diarrheagenic E. coli were predominant in children less than two years of age, while Shigella spp, and enterotoxigenic B. fragilis were mostly seen in the older children. Diarrheagenic E. coli and Shigella spp showed high prevalence of resistance to ampicillin, chloramphenicol, and to trimethoprim/sulfamethoxazole. Children attending the hospitals had fever (43.6%), vomiting (53.8%), and dehydration (82.6%). Watery stool was predominant with a prevalence of 66.4%, followed by mucous stool (21.0%). The mean episodes of stools per day was seven, ranging from two to 23 episodes. Before attending hospitals, 162/587 (27.6%) children had been given antibiotics. Overall, more children got diarrhea in (i) poor families; (ii) families where piped water and a latrine were lacking; (iii) families where mothers washed their hands less often before feeding the children; (iv) families where mothers had a low level of education; (v) families where information on health and sanitation less often reached their households.

CONCLUSIONS

Group A rotavirus, diarrheagenic Escherichia coli, Shigella spp, and enterotoxigenic Bacteroides fragilis play an important role in causing diarrhea in children in Hanoi, Vietnam. Epidemiological factors such as lack of fresh water supply, unhygienic septic tank, low family income, lack of health information, and low educational level of parents could contribute to the morbidity of diarrhea in children.

Etiology of diarrheal infections in children of Porto Velho (Rondonia, Western Amazon region, Brazil)

In the present study, 470 children less than 72 months of age and presenting acute diarrhea were examined to identify associated enteropathogenic agents. Viruses were the pathogens most frequently found in stools of infants with diarrhea, including 111 cases of rotavirus (23.6% of the total diarrhea cases) and 30 cases of adenovirus (6.3%). The second group was diarrheogenic Escherichia coli (86 cases, 18.2%), followed by Salmonella sp (44 cases, 9.3%) and Shigella sp (24 cases, 5.1%). Using the PCR technique to differentiate the pathogenic categories of E. coli, it was possible to identify 29 cases (6.1%) of enteropathogenic E. coli (EPEC). Of these, 10 (2.1%) were typical EPEC and 19 (4.0%) atypical EPEC. In addition, there were 26 cases (5.5%) of enteroaggregative E. coli, 21 cases (4.4%) of enterotoxigenic E. coli, 7 cases (1.4%) of enteroinvasive E. coli (EIEC), and 3 cases (0.6%) of enterohemorrhagic E. coli. When comparing the frequencies of diarrheogenic E. coli, EPEC was the only category for which significant differences were found between diarrhea and control groups. A low frequency of EIEC was found, thus EIEC cannot be considered to be a potential etiology agent of diarrhea. Simultaneous infections with two pathogens were found in 39 diarrhea cases but not in controls, suggesting associations among potential enteropathogens in the etiology of diarrhea. The frequent association of diarrheogenic E. coli strains was significantly higher than the probability of their random association, suggesting the presence of facilitating factor(s).

Slot blot immunoassay as a tool for plasmid-encoded toxin detection in enteroaggregative Escherichia coli culture supernatants

Plasmid-encoded toxin (Pet) is a heat-labile enterotoxin encoded in the enteroaggregative Escherichia coli (EAEC) virulence plasmid. Several evidence support the role of this 108-kDa secreted protein in the pathogenesis of EAEC diarrhea. In this study, we standardized a slot blot immunoassay for Pet detection. EAEC culture supernatants were applied onto a polyvinylidene difluoride membrane, and, using rabbit polyclonal Pet antisera, the expression of the toxin by slot blot immunoassay was observed in 9.5% of the isolates studied. In addition, no negative control reacted with Pet antiserum in this assay. This assay is a rapid, specific, reproducible, and low-cost methodology, therefore demonstrating its potential in diagnosing Pet expression. Moreover, we describe for the first time that expression of Pet can be directly detected from EAEC culture supernatants and may be used in clinical laboratorial routine instead of polymerase chain reaction detection of the pet gene, especially in developing countries where the EAEC pathotype has been considered an emerging pathogen.

Enteroaggregative Escherichia coli: An emerging pathogen in children

Enteroaggregative Escherichia coli (EAEC) is an emerging pathogen that causes enteric and food-borne infectious diseases. Children throughout the world appear to be susceptible to EAEC infection. EAEC pathogenesis involves the following three stages: 1) adherence to the intestinal mucosa; 2) increased production and deposition of a mucus biofilm; and 3) mucosal toxicity due to inflammation and cytokine release. The HEp-2 cell adherent assay allows identification of EAECs characteristic aggregative or "stacked brick" adherence pattern. Antimicrobial treatment of children who develop an EAEC infection should be individually based. All children with EAEC diarrhea should receive adequate oral fluid hydration. For children who have persistent diarrhea and severe dehydrating illness despite having received adequate oral rehydration, antimicrobials may be initiated. Azithromycin and rifaximin have been shown to shorten the course of EAEC diarrhea in adults and probably represent the recommended antimicrobials of choice for children with severe or persistent illness. The objective of this review is to increase awareness of this important emerging pathogen and to discuss the epidemiology, pathogenesis, and pathogen and host factors associated with EAEC infection in children.

Reduced etiological role for enteropathogenic Escherichia coli in cases of diarrhea in Brazilian infants

Previously common in Brazil, enteropathogenic Escherichia coli (EPEC) strains of serogroups O55, O111, and O119 are now rare, while enteroadherent strains other than EPEC, belonging to serogroups such as O125, were prevalent among 126 diarrheic infants less than 1 year old who were surveyed. None of these strains had the EPEC bundle-forming pilus (bfpA) gene.