Infectious diarrhoea contributes to high morbidity and mortality in young children from sub-Saharan Africa. The aim of this study was to assess the prevalence of single and multiple diarrhoeal-causing pathogen combinations in children suffering from diarrhoea from rural and peri-urban communities in South Africa. A total of 275 diarrhoea stool specimens were collected between 2014 and 2016 from Hospitals and Primary Health Care clinics. The BioFire® FilmArray® Gastrointestinal panel was used to simultaneously detect 22 diarrhoea pathogens (viruses, bacteria, parasites) known to cause diarrhoea. A total of 82% (226/275) enteric pathogens were detected in the stool specimens. The two most detected bacterial, viral and parasitic pathogens each included: EAEC (42%), EPEC (32%), Adenovirus F40/41 (19%), Norovirus (15%), Giardia (8%) and Cryptosporidium (6%), respectively. Single enteric pathogen infections were recorded in 24% (65/275) specimens with EAEC, and Norovirus was found in 26% (17/65) and 14% (9/65) of the specimens, respectively. Multiple enteric pathogen combinations were recorded in 59% (161/275) of the stool specimens with 53% (85/161) containing two pathogens, 22% (35/161) containing three pathogens and 25% (41/161) containing four or more pathogens. The results from this study demonstrated the complex nature of pathogen co-infections in diarrhoeal episodes which could have an impact on treatment effectiveness.

Bundle-forming pili (BFP) are implicated in the virulence of typical enteropathogenic E. coli (EPEC), resulting in enhanced colonization and mild to severe disease outcomes; hence, non-functional BFP may have a major influence on disease outcomes in vivo. Weaned antibiotic pre-treated C57BL/6 mice were orally infected with EPEC strain UMD901 (E2348/69 bfpA C129S); mice were monitored daily for body weight; stool specimens were collected daily; and intestinal tissues were collected at the termination of the experiment on day 3 post-infection. Real-time PCR was used to quantify fecal shedding and tissue burden. Intestinal inflammatory biomarkers lipocalin-2 (LCN-2) and myeloperoxidase (MPO) were also assessed. Infection caused substantial body weight loss, bloody diarrhea, and intestinal colonization with fecal and intestinal tissue inflammatory biomarkers that were comparable to those previously published with the wild-type typical EPEC strain. Here we further report on the evaluation of an EPEC infection model, showing how disruption of bfp function does not impair, and may even worsen diarrhea, colonization, and intestinal disruption and inflammation. More research is needed to understand the role of bfp in pathogenicity of EPEC infections in vivo.

The involvement of the enteric nervous system, which is a source of S100B, in Clostridioides difficile (C. difficile) infection (CDI) is poorly understood although intestinal motility dysfunctions are known to occur following infection. Here, we investigated the role of S100B in CDI and examined the S100B signaling pathways activated in C. difficile toxin A (TcdA)- and B (TcdB)-induced enteric glial cell (EGC) inflammatory response. The expression of S100B was measured in colon tissues and fecal samples of patients with and without CDI, as well as in colon tissues from C. difficile-infected mice. To investigate the role of S100B signaling in IL-6 expression induced by TcdA and TcdB, rat EGCs were used. Increased S100B was found in colonic biopsies from patients with CDI and colon tissues from C. difficile-infected mice. Patients with CDI-promoted diarrhea exhibited higher levels of fecal S100B compared to non-CDI cases. Inhibition of S100B by pentamidine reduced the synthesis of IL-1β, IL-18, IL-6, GMCSF, TNF-α, IL-17, IL-23, and IL-2 and downregulated a variety of NFκB-related genes, increased the transcription (SOCS2 and Bcl-2) of protective mediators, reduced neutrophil recruitment, and ameliorated intestinal damage and diarrhea severity in mice. In EGCs, TcdA and TcdB upregulated S100B-mediated IL-6 expression via activation of RAGE/PI3K/NFκB. Thus, CDI appears to upregulate colonic S100B signaling in EGCs, which in turn augment inflammatory response. Inhibition of S100B activity attenuates the intestinal injury and diarrhea caused by C. difficile toxins. Our findings provide new insight into the role of S100B in CDI pathogenesis and opens novel avenues for therapeutic interventions.

Enteropathogenic E. coli (EPEC) are recognized as one of the leading bacterial causes of infantile diarrhea worldwide. Weaned C57BL/6 mice pretreated with antibiotics were challenged orally with wild-type EPEC or escN mutant (lacking type 3 secretion system) to determine colonization, inflammatory responses and clinical outcomes during infection. Antibiotic disruption of intestinal microbiota enabled efficient colonization by wild-type EPEC resulting in growth impairment and diarrhea. Increase in inflammatory biomarkers, chemokines, cellular recruitment and pro-inflammatory cytokines were observed in intestinal tissues. Metabolomic changes were also observed in EPEC infected mice with changes in tricarboxylic acid (TCA) cycle intermediates, increased creatine excretion and shifts in gut microbial metabolite levels. In addition, by 7 days after infection, although weights were recovering, EPEC-infected mice had increased intestinal permeability and decreased colonic claudin-1 levels. The escN mutant colonized the mice with no weight loss or increased inflammatory biomarkers, showing the importance of the T3SS in EPEC virulence in this model. In conclusion, a murine infection model treated with antibiotics has been developed to mimic clinical outcomes seen in children with EPEC infection and to examine potential roles of selected virulence traits. This model can help in further understanding mechanisms involved in the pathogenesis of EPEC infections and potential outcomes and thus assist in the development of potential preventive or therapeutic interventions.

Vaccine studies for Shigella flexneri and enterotoxigenic Escherichia coli have been impaired by the lack of optimal animal models. We used two murine models to show that a S. flexneri 2a bivalent vaccine (CVD 1208S-122) expressing enterotoxigenic Escherichia coli colonization factor antigen-I (CFA/I) and the binding subunits A2 and B of heat labile-enterotoxin (LTb) is immunogenic and protects against weight loss and diarrhea. These findings document the immunogenicity and pre-clinical efficacy effects of CVD 1208S-122 vaccine and suggest that further work can help elucidate relevant immune responses and ultimately its clinical efficacy in humans.

Background: Young children exhibit a high susceptibility to several diarrhoea-causing bacterial microorganisms. In this study, the prevalence of fecal contamination on children’s toys was determined using total coliform and E. coli as bacterial fecal indicators. The prevalence of diarrhoeagenic E. coli strains were used as an indication of the potential health risks. Materials and Methods: A cross-sectional descriptive study was carried out for 3 months in rural communities in the Vhembe district, Limpopo province of South Africa. Nonporous plastic toys (n = 137) used by children under 5 years of age in households and day care centres (DCCs) from rural villages were collected for assessment. New toys (n = 109) were provided to the households and DCCs and collected again after 4 weeks. Microbiological assessment was carried out using the Colilert® Quanti-Tray/2000 system. Diarrhoeagenic E. coli strains were identified using a published multiplex PCR protocol. Results: Water, sanitation and hygiene (WASH) conditions of the children in the households and DCCs were assessed. Statistical analysis was used to identify the relationship between fecal contamination of the existing and introduced toys. All the existing and introduced toy samples, both from DCCs and households, tested positive for total coliform counts and 61 existing and introduced toy samples tested positive for E. coli counts. Diarrhoeagenic E. coli strains identified included EHEC, ETEC, EPEC, EIEC and EAEC. Conclusions: The results indicated that water, sanitation and hygiene conditions could be responsible in the contamination of children’s toys and the transmission of diarrhoea to young children.

Shigella is one of the major enteric pathogens worldwide. We present a murine model of S. flexneri infection and investigate the role of zinc deficiency (ZD). C57BL/6 mice fed either standard chow (HC) or ZD diets were pretreated with an antibiotic cocktail and received S. flexneri strain 2457T orally. Antibiotic pre-treated ZD mice showed higher S. flexneri colonization than non-treated mice. ZD mice showed persistent colonization for at least 50 days post-infection (pi). S. flexneri-infected mice showed significant weight loss, diarrhea and increased levels of fecal MPO and LCN in both HC and ZD fed mice. S. flexneri preferentially colonized the colon, caused epithelial disruption and inflammatory cell infiltrate, and promoted cytokine production which correlated with weight loss and histopathological changes. Infection with S. flexneri Delta mxiG (critical for type 3 secretion system) did not cause weight loss or diarrhea, and had decreased stool shedding duration and tissue burden. Several biochemical changes related to energy, inflammation and gut-microbial metabolism were observed. Zinc supplementation increased weight gains and reduced intestinal inflammation and stool shedding in ZD infected mice. In conclusion, young antibiotic-treated mice provide a new model of oral S. flexneri infection, with ZD promoting prolonged infection outcomes.

Campylobacter infections are among the leading bacterial causes of diarrhea and of 'environmental enteropathy' (EE) and growth failure worldwide. However, the lack of an inexpensive small animal model of enteric disease with Campylobacter has been a major limitation for understanding its pathogenesis, interventions or vaccine development. We describe a robust standard mouse model that can exhibit reproducible bloody diarrhea or growth failure, depending on the zinc or protein deficient diet and on antibiotic alteration of normal microbiota prior to infection. Zinc deficiency and the use of antibiotics create a niche for Campylobacter infection to establish by narrowing the metabolic flexibility of these mice for pathogen clearance and by promoting intestinal and systemic inflammation. Several biomarkers and intestinal pathology in this model also mimic those seen in human disease. This model provides a novel tool to test specific hypotheses regarding disease pathogenesis as well as vaccine development that is currently in progress.

Background Human Bocavirus (HBoV) is an emerging virus discovered in 2005 from individuals suffering gastroenteritis and respiratory tract infections. Numerous studies related to the epidemiology and pathogenesis of HBoV have been conducted worldwide. This review reports on HBoV studies in individuals with acute gastroenteritis, with and without respiratory tract infections in Africa between 2005 and 2016. Material and Method The search engines of PubMed, Google Scholar, and Embase database for published articles of HBoV were used to obtain data between 2005 and 2016. The search words included were as follows: studies performed in Africa or/other developing countries or/worldwide; studies for the detection of HBoV in patients with/without diarrhea and respiratory tract infection; studies using standardized laboratory techniques for detection. Results The search yielded a total of 756 publications with 70 studies meeting the inclusion criteria. Studies included children and individuals of all age groups. HBoV prevalence in Africa was 13% in individuals suffering gastroenteritis with/without respiratory tract infection. Conclusion Reports suggest that HBoV infections are increasingly being recognized worldwide. Therefore, surveillance of individuals suffering from infections in Africa is required to monitor the prevalence of HBoV and help understand the role of HBoV in individuals suffering from gastroenteritis with/without respiratory tract infection.