The Global Enteric Multicenter Study (GEMS) of diarrheal disease in infants and young children in developing countries: epidemiologic and clinical methods of the case/control study

Characterization of a novel plasmid encoding F4-like fimbriae present in a Shiga-toxin producing enterotoxigenic Escherichia coli isolated during the investigation on a case of hemolytic-uremic syndrome

In February 2017 a case of Hemolytic-Uremic Syndrome (HUS) was reported to the National Registry of HUS in an adult living in Northern Italy. Stool specimens from the patient and his family contacts were collected and the analyses led to the isolation of a Locus of Enterocyte Effacement (LEE)-negative Shiga toxin 2 (Stx2)-producing Escherichia coli. The epidemiological investigations performed brought to collect fecal samples from the animals reared in a farm held by the case's family and a mixture of bovine and swine feces proved positive for Shiga toxin-producing E. coli (STEC) and yielded the isolation of a LEE-negative stx2-positive E. coli strain. Further characterization by whole genome sequencing led to identify the isolates as two identical O2:H27 hybrid Enterotoxigenic Shiga toxin-producing E. coli (ETEC-STEC). Sequencing of a high molecular weight plasmid present in the human isolate disclosed a peculiar plasmid harboring virulence genes characteristic for both pathotypes, including the enterohemolysin-coding gene and sta1, encoding the heat stable enterotoxin. Moreover, a complete fae locus encoding the ETEC F4 fimbriae could be identified, including a novel variant of faeG gene responsible for the production of the main structural subunit of the fimbriae. This novel faeG showed great diversity in the nucleotidic sequence when compared with the reference genes encoding the swine F4 allelic variants, whereas at the amino acid sequence level the predicted protein sequence showed some similarity with FaeG from E. coli strains of bovine origin. Further investigation on the plasmid region harboring the newly identified faeG allelic variant allowed to identify similar plasmids in NCBI sequence database, as part of the genome of other previously uncharacterized ETEC-STEC strains of bovine origin, suggesting that the novel F4-like fimbriae may play a role in bovine host specificity.

Co-administered Tag-Less Toxoid Fusion 3xSTaN12S-mnLTR192G/L211A and CFA/I/II/IV MEFA (Multiepitope Fusion Antigen) Induce Neutralizing Antibodies to 7 Adhesins (CFA/I, CS1-CS6) and Both Enterotoxins (LT, STa) of Enterotoxigenic Escherichia coli (ETEC)

Enterotoxigenic Escherichia coli (ETEC) bacteria remain a leading cause of children's diarrhea and travelers' diarrhea. Vaccines that induce antibodies to block ETEC bacterial adherence and to neutralize toxin enterotoxicity can be effective against ETEC-associated diarrhea. Recent studies showed that 6xHis-tagged CFA/I/II/IV multiepitope fusion antigen (MEFA) induced broad-spectrum antibodies to inhibit adherence of the seven most important ETEC adhesins (CFA/I, CS1 to CS6) (Ruan et al., 2014a) and 6xHis-tagged toxoid fusion antigen 3xSTaN12S-mnLTR192G/L211A (previously named as 3xSTaN12S-dmLT) elicited antibodies to neutralize both heat-labile toxin (LT) and heat-stable toxin (STa) produced by ETEC strains (Ruan et al., 2014b). In this study, we constructed two new genes to express tag-less toxoid fusion 3xSTaN12S-mnLTR192G/L211A and tag-less CFA/I/II/IV MEFA and then examined immunogenicity of each tag-less protein in mouse immunization. We further combined two tag-less proteins and investigated antigen co-administration in mice. Data showed that mice immunized with tag-less 3xSTaN12S-mnLTR192G/L211A or tag-less CFA/I/II/IV MEFA developed antigen-specific IgG antibody responses, and mice co-administered with two tag-less proteins induced neutralizing antibodies against seven adhesins and both toxins. These results indicated tag-less toxoid fusion 3xSTaN12S-mnLTR192G/L211A and tag-less CFA/I/II/IV MEFA administered individually or combined induced neutralizing antitoxin and/or anti-adhesin antibodies, and suggested the potential application of two tag-less proteins for ETEC vaccine development.

The role of HIV infection in the etiology and epidemiology of diarrheal disease among children aged 0-59 months in Manhiça District, Rural Mozambique

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HIV prevalence was higher among cases with moderate-to-severe diarrhea (MSD) than controls.

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Mortality was higher among HIV-infected children with diarrhea than HIV-uninfected ones.

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HIV-infected children were more likely to have MSD.

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Cryptosporidium was the most common pathogen in HIV-infected children with MSD.

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Escherichia coli producing heat-stable toxin (enterotoxigenic Escherichia coli, any sequence type) was the most common pathogen in HIV-infected children with less severe diarrhea.

Background

Diarrhea is an important health problem among HIV-infected patients. This study evaluated the role of HIV in the epidemiology, etiology, and severity of diarrheal disease among children.

Methods

The Global Enteric Multicenter Study enrolled children with moderate-to-severe diarrhea (MSD) and less-severe diarrhea (LSD) between December 2007 and November 2012. One to three controls for MSD cases and one per LSD case were enrolled and matched by age, sex, and neighborhood. All children were tested for HIV. Clinical data, anthropometric data, and stool samples were collected. Follow-up was performed at 60 days.

Results

Two hundred and fourteen MSD cases and 418 controls, together with 349 LSD cases and 214 controls were tested. HIV prevalence was 25% among MSD cases (4% for matched controls) and 6% among LSD cases (6% among matched controls). HIV-infected children were more likely to have MSD (odds ratio 5.6, p < 0.0001).

Mortality rates were higher among HIV-infected children than among the uninfected (34 vs. 5 per 1000 child-weeks at risk; p = 0.0039). Cryptosporidium, Giardia, and enteroaggregative Escherichia coli (aatA only) were more prevalent among HIV-infected MSD cases than among uninfected ones.

Conclusion

HIV is an important risk factor for MSD. The high mortality rate implies that children with MSD should be screened for HIV and managed accordingly.

Pneumonia mortality and healthcare utilization in young children in rural Bangladesh: a prospective verbal autopsy study

Background

The present study aimed to examine the risk factors for death due to pneumonia in young children and healthcare behaviors of the guardians for children in rural Bangladesh. A prospective autopsy study was conducted among guardians of children aged 4 weeks to 59 months in Mirzapur, Bangladesh, from 2008 to 2012.

Results

Pneumonia was the primary cause of death, accounting for 26.4% (n = 81) of all 307 deaths. Of the pneumonia deaths, 58% (n = 47) deaths occurred in younger infants (aged 4 weeks to < 6 months) and 24.7% (n = 20) in older infants (aged 6–11 months). The median duration of illness before pneumonia death was 8 days (interquartile range [IQR] 3–20 days). Prior to death, 91.4% (n = 74) children with pneumonia sought treatment, and of those who sought treatment, 52.7% (n = 39) sought treatment ≥ 2 days after the onset of disease. Younger infants of 4 weeks to < 6 months old were at 5.5-time (95% confidence interval [CI] 2.5, 12.0) and older infants aged 6–11 months were at 3-time (1.2, 7.5) greater risk of dying from pneumonia than older children aged 12–59 months. Children with a prolonged duration of illness (2–10 days) prior to death were at more risk for death by pneumonia than those who died from other causes (5.8 [2.1, 16.1]). Children who died from pneumonia sought treatment 3.4-time more than children who died from other causes. Delayed treatment seeking (≥ 2 days) behavior was 4.9-time more common in children who died from pneumonia than those who died from other causes. Children who died from pneumonia more often had access to care from multiple sources (5.7-time) than children who died from other causes.

Conclusions

Delay in seeking appropriate care and access to multiple sources for treatment are the underlying risk factors for pneumonia death in young children in Bangladesh. These results indicate the perplexity in guardians’ decisions to secure appropriate treatment for children with pneumonia. Therefore, it further underscores the importance of focusing on mass media coverage that can outline the benefits of seeking care early in the progression of pneumonia and the potential negative consequences of seeking care late.

Electronic supplementary material

The online version of this article (10.1186/s41182-018-0099-4) contains supplementary material, which is available to authorized users.

Burden and Risk Factors of Antimicrobial Use in Children Less Than 5 Years of Age with Diarrheal Illness in Rural Bangladesh

Antimicrobial overuse contributes to antimicrobial resistance. Empiric use of antimicrobials for diarrheal illness is warranted only in a minority of cases, because of its self-limiting nature and multifactorial etiology. This study aims to describe the factors contributing to antimicrobial overuse for diarrheal disease among children less than 5 years of age in rural Bangladesh. A total of 3,570 children less than 5 years of age presenting with diarrhea in a tertiary level hospital were enrolled in the study. The rate of antimicrobial use at home was 1,395 (39%), compared with 2,084 (89%) during a hospital visit. In a multivariate analysis, factors associated with antimicrobial use at home included residence located more than 5 miles from a hospital; use of zinc and oral rehydration salts at home; vomiting; greater than 10 stools per 24 hours; diarrheal duration greater than 3 days; and rotavirus diarrhea (P < 0.05 for all). Characteristics of children more likely to be given antimicrobials in a health-care setting included greater than 10 stools per 24 hours; duration of diarrhea greater than 3 days; use of antimicrobials before hospital presentation; fever (≥ 37.8°C); rectal straining; and Shigella infection (P < 0.05 for all). The most commonly used drugs in rotavirus diarrhea were azithromycin and erythromycin, both before hospital presentation and during hospital admission. Our study underscores the importance of diligent vigilance on the rationale use of antimicrobials both at home and in health-care facilities with a special concern for children less than 5 years of age living in rural Bangladesh.

Comparison of current methods used to detect Cryptosporidium oocysts in stools

In this review all of the methods that are currently in use for the investigation of Cryptosporidium in stool material are highlighted and critically discussed. It appears that more qualifications and background knowledge in this field regarding the diagnosis of the Cryptosporidium parasite is required. Furthermore, there is no standardization for the protocols that are commonly used to either detect oocysts in faeces or to diagnose the Cryptosporidium infection. It is therefore necessary to initiate further education and research that will assist in improving the accuracy of the diagnosis of Cryptosporidium oocysts in the faecal micro-cosmos. Where ambient concentrations of oocysts are low in stool material, detection becomes a formidable task. Procedures for ring tests and the standardization of multi-laboratory testing are recommended. It is also necessary to enhance the routine surveillance capacity of cryptosporidiosis and to improve the safety against it, considering the fact that this disease is under diagnosed and under reported. This review is intended to stimulate research that could lead to future improvements and further developments in monitoring the diagnostic methodologies that will assist in harmonizing Cryptosporidium oocysts in stool diagnosis.

Geographic coverage of demographic surveillance systems for characterising the drivers of childhood mortality in sub-Saharan Africa

A major focus of international health and development goals is the reduction of mortality rates in children under 5 years of age. Achieving this requires understanding the drivers of mortality and how they vary geographically to facilitate the targeting and prioritisation of appropriate interventions. Much of our knowledge on the causes of, and trends in, childhood mortality come from longitudinal demographic surveillance sites, with a renewed focus recently on the establishment and growth of networks of sites from which standardised outputs can facilitate broader understanding of processes. To ensure that the collective outputs from surveillance sites can be used to derive a comprehensive understanding and monitoring system for driving policy on tackling childhood mortality, confidence is needed that existing and planned networks of sites are providing a reliable and representative picture of the geographical variation in factors associated with mortality. Here, we assembled subnational data on childhood mortality as well as key factors known to be associated with it from household surveys in 27 sub-Saharan African countries. We then mapped the locations of existing longitudinal demographic surveillance sites to assess the extent of current coverage of the range of factors, identifying where gaps exist. The results highlight regions with unique combinations of factors associated with childhood mortality that are poorly represented by the current distribution of sites, such as southern Mali, central Nigeria and southern Zambia. Finally, we determined where the establishment of new surveillance systems could improve coverage.

Lateral Flow Loop-Mediated Isothermal Amplification Test with Stem Primers: Detection of Cryptosporidium Species in Kenyan Children Presenting with Diarrhea

Background. Cryptosporidium is a protozoan parasite and a major cause of diarrhea in children and immunocompromised patients. Current diagnostic methods for cryptosporidiosis such as microscopy have low sensitivity while techniques such as PCR indicate higher sensitivity levels but are seldom used in developing countries due to their associated cost. A loop-mediated isothermal amplification (LAMP) technique, a method with shorter time to result and with equal or higher sensitivity compared to PCR, has been developed and applied in the detection of Cryptosporidium species. The test has a detection limit of 10 pg/µl (~100 oocysts/ml) indicating a need for more sensitive diagnostic tools. This study developed a more sensitive lateral flow dipstick (LFD) LAMP test based on SAM-1 gene and with the addition of a second set of reaction accelerating primers (stem primers). Results. The stem LFD LAMP test showed analytical sensitivity of 10 oocysts/ml compared to 100 oocysts/ml (10 pg/ul) for each of the SAM-1 LAMP test and nested PCR. The stem LFD LAMP and nested PCR detected 29/39 and 25/39 positive samples of previously identified C. parvum and C. hominis DNA, respectively. The SAM-1 LAMP detected 27/39. On detection of Cryptosporidium DNA in 67 clinical samples, the stem LFD LAMP detected 16 samples and SAM-2 LAMP 14 and nested PCR identified 11. Preheating the templates increased detection by stem LFD LAMP to 19 samples. Time to results from master mix preparation step took ~80 minutes. The test was specific, and no cross-amplification was recorded with nontarget DNA. Conclusion. The developed stem LFD LAMP test is an appropriate method for the detection of C. hominis, C. parvum, and C. meleagridis DNA in human stool samples. It can be used in algorithm with other diagnostic tests and may offer promise as an effective diagnostic tool in the control of cryptosporidiosis.

Enterotoxigenic Escherichia coli Adhesin-Toxoid Multiepitope Fusion Antigen CFA/I/II/IV-3xSTaN12S-mnLTG192G/L211A-Derived Antibodies Inhibit Adherence of Seven Adhesins, Neutralize Enterotoxicity of LT and STa Toxins, and Protect Piglets against Diarrhea

Enterotoxigenic Escherichia coli (ETEC) strains are a leading cause of children's diarrhea and travelers' diarrhea. Vaccines inducing antibodies to broadly inhibit bacterial adherence and to neutralize toxin enterotoxicity are expected to be effective against ETEC-associated diarrhea. 6×His-tagged adhesin-toxoid fusion proteins were shown to induce neutralizing antibodies to several adhesins and LT and STa toxins (X. Ruan, D. A. Sack, W. Zhang, PLoS One 10:e0121623, 2015, https://doi.org/10.1371/journal.pone.0121623). However, antibodies derived from His-tagged CFA/I/II/IV-2xSTa_A14Q-dmLT or CFA/I/II/IV-2xSTa_N12S-dmLT protein were less effective in neutralizing STa enterotoxicity and were not evaluated in vivo for efficacy against ETEC diarrhea. Additionally, His-tagged proteins are considered less desirable for human vaccines. In this study, we produced a tagless adhesin-toxoid MEFA (multiepitope fusion antigen) protein, enhanced anti-STa immunogenicity by including a third copy of STa toxoid STa_N12S, and examined antigen immunogenicity in a murine model. Moreover, we immunized pregnant pigs with the tagless adhesin-toxoid MEFA protein and evaluated passive antibody protection against STa⁺ or LT⁺ ETEC infection in a pig challenge model. Results showed that tagless adhesin-toxoid MEFA CFA/I/II/IV-3xSTa_N12S-mnLT_R192G/L211A induced broad antiadhesin and antitoxin antibody responses in the intraperitoneally immunized mice and the intramuscularly immunized pigs. Mouse and pig serum antibodies significantly inhibited adherence of seven colonization factor antigen (CFA) adhesins (CFA/I and CS1 to CS6) and effectively neutralized both toxins. More importantly, suckling piglets born to the immunized mothers acquired antibodies and were protected against STa⁺ ETEC and LT⁺ ETEC diarrhea. These results indicated that tagless CFA/I/II/IV-3xSTa_N12S-mnLT_R192G/L211A induced broadly protective antiadhesin and antitoxin antibodies and demonstrate that this adhesin-toxoid MEFA is a potential antigen for developing broadly protective ETEC vaccines.

Antibiotic resistance and molecular characterization of shigella isolates recovered from children aged less than 5 years in Manhiça, Southern Mozambique

The objective of this study was to assess antibiotic resistance and the molecular epidemiology of shigella isolates from a case-control study of diarrhoea, conducted from 2007 to 2012 in children aged less than 5 years in Manhiça district, southern Mozambique. All isolates were tested for antimicrobial susceptibility using the disc diffusion method. Polymerase chain reaction was used to detect different molecular mechanisms of antibiotic resistance. Serotyping was performed using specific antisera. The clonal relationship of Shigella flexneri and Shigella sonnei was assessed by pulsed-field gel electrophoresis (PFGE). Of the 67 shigella isolates analysed, 59 were diarrhoeal cases and eight were controls. S. flexneri (70.1%; 47/67) was the most common species, followed by S. sonnei (23.9%; 16/67). The most prevalent S. flexneri serotypes were 2a (38.3%; 18/47), 6 (19.2%; 9/47) and 1b (14.9%; 7/47). High rates of antimicrobial resistance were observed for trimethoprim-sulfametoxazole (92.5%; 62/67), tetracycline (68.7%; 46/67), chloramphenicol (53.7%; 36/67) and ampicillin (50.7%; 34/67). Multi-drug resistance (MDR) was present in 55.2% (37/67) of the isolates and was associated with a case fatality rate of 8.1% (3/37). PFGE revealed 22 clones (16 S. flexneri and 6 S. sonnei), among which P1 (31.9%; 15/47), P9 (17%; 8/47) and P2 (10.6%; 5/47) were the most prevalent clones of S. flexneri. In conclusion, S. flexneri was the most prevalent species, with MDR isolates mainly belonging to three specific clones (P1, P9 and P2). The case fatality rate observed among MDR isolates is a matter of concern, indicating the need for appropriate treatment.

Reporting of ethics in peer-reviewed verbal autopsy studies: a systematic review

Introduction

Verbal autopsy (VA) is a method that determines the cause of death by interviewing a relative of the deceased about the events occurring before the death, in regions where medical certification of cause of death is incomplete. This paper aims to review the ethical standards reported in peer-reviewed VA studies.

Methods

A systematic review of Medline and Ovid was conducted by two independent researchers. Data were extracted and analysed for articles based on three key areas: Institutional Review Board (IRB) clearance and consenting process; data collection and management procedures, including: time between death and interview; training and education of interviewer, confidentiality of data and data security; and declarations of funding and conflict of interest.

Results

The review identified 802 articles, of which 288 were included. The review found that 48% all the studies reported having IRB clearance or obtaining consent of participants. The interviewer training and education levels were reported in 62% and 21% of the articles, respectively. Confidentiality of data was reported for 14% of all studies, 18% did not report the type of respondent interviewed and 51% reported time between death and the interview for the VA. Data security was reported in 8% of all studies. Funding was declared in 63% of all studies and conflict of interest in 42%. Reporting of all these variables increased over time.

Conclusions

The results of this systematic review show that although there has been an increase in ethical reporting for VA studies, there still remains a large gap in reporting.

Molecular characterization of diarrheagenic Escherichia coli pathotypes: Association of virulent genes, serogroups, and antibiotic resistance among moderate-to-severe diarrhea patients

BACKGROUND

Diarrheagenic Escherichia coli (DEC) signifies as an important etiological agent of moderate-to-severe diarrhea. This study was primarily focused on molecular identification of DEC pathotypes; their association with serogroups and estimates of resistance profiles against different antibiotics regime.

METHODS

Five hundred seventy-two stool specimens from diarrhea patients were investigated for DEC pathotypes. Molecular pathotypes were identified by amplification of virulence genes associated with distinct pathotypes followed by sequencing. Diarrhea is a self-limiting disease, however, severity and persistence of infection suggest antibiotic use. Therefore, AST and MIC were determined against common antibiotic regimen. Correlations between molecular pathotypes and serogroups were analyzed by somatic "O" antigen serotyping.

RESULTS

The present findings reveal incidence of DEC as an etiological agent up to a level of 21% among all diarrheal age groups. DEC infection rate was higher in children. Enteropathogenic E. coliEPEC, a molecular pathotype of DEC, was found as a predominant pathotype with highest frequency of 13.7%. Two other molecular pathotypes enterotoxigenic E. coli (ETEC) and enteroaggregative E. coli (EAEC) accounted for 5.7% and 1.3%, respectively for all diarrhea incidences. Serological analysis deciphered somatic antigens O26, O2, and O3 as major serogroups identified among EPEC, ETEC, and EAEC pathotypes, respectively. All DEC pathotypes exhibited high levels of antibiotic resistance except for cotrimoxazole and norfloxacin.

CONCLUSION

Comprehensive molecular characterization of DEC pathotypes, their incidence estimates, and antibiogram patterns will help in ascertaining better diagnostic and therapeutic measures in management of diarrheal diseases.

Neutralizing Anti-Heat-Stable Toxin (STa) Antibodies Derived from Enterotoxigenic Escherichia coli Toxoid Fusions with STa Proteins Containing N12S, L9A/N12S, or N12S/A14T Mutations Show Little Cross-Reactivity with Guanylin or Uroguanylin

Heat-stable toxin (STa)-producing enterotoxigenic Escherichia coli (ETEC) strains are a top cause of moderate-to-severe diarrhea in children from developing countries and a common cause of travelers' diarrhea. Recent progress in using STa toxoids and toxoid fusions to induce neutralizing anti-STa antibodies has accelerated ETEC vaccine development. However, concern remains regarding whether the derived anti-STa antibodies cross-react with STa-like guanylin and uroguanylin, two guanylate cyclase C (GC-C) ligands regulating fluid and electrolyte transportation in human intestinal and renal epithelial cells. To further divert STa from guanylin and uroguanylin structurally and antigenically and to eliminate anti-STa antibody cross-reactivity with guanylin and uroguanylin, we mutated STa at the 9th (leucine), 12th (asparagine), and 14th (alanine) residues for the double and triple mutants STa_L9A/N12S, STa_L9A/A14H, STa_N12S/A14T, and STa_{L9A/N12S/A14H} We then fused each STa mutant (three copies) to a monomeric heat-labile toxin (LT) mutant (mnLT_R192G/L211A) for the toxoid fusions 3×STa_L9A/N12S-mnLT_R192G/L211A, 3×STa_L9A/A14H-mnLT_R192G/L211A, 3×STa_N12S/A14T-mnLT_R192G/L211A, and 3×STa_{L9A/N12S/A14H}-mnLT_R192G/L211A; examined each fusion for anti-STa immunogenicity; and assessed the derived antibodies for in vitro neutralization activity against STa toxicity and for cross-reactivity with guanylin and uroguanylin. Mice subcutaneously immunized with each fusion protein developed anti-STa antibodies, and the antibodies derived from 3×STa_N12S-mnLT_R192G/L211A, 3×STa_L9A/N12S-mnLT_R192G/L211A, or 3×STa_N12S/A14T-mnLT_R192G/L211A prevented STa from the stimulation of intracellular cGMP in T-84 cells. Competitive enzyme-linked immunosorbent assays (ELISAs) showed that guanylin and uroguanylin hardly blocked the binding of anti-STa antibodies to the coated STa-ovalbumin conjugate. These results indicated that antibodies derived from 3×STa_N12S-mnLT_R192G/L211A, 3×STa_L9A/N12S-mnLT_R192G/L211A, or 3×STa_N12S/A14T-mnLT_R192G/L211A neutralized STa and had little cross-reactivity with guanylin and uroguanylin, suggesting that these toxoid fusions are suitable antigens for ETEC vaccines.IMPORTANCE Enterotoxigenic Escherichia coli (ETEC) strains are a leading cause of children's diarrhea and travelers' diarrhea. Currently, there is no licensed vaccine against ETEC diarrhea. One key challenge is to identify safe antigens to induce antibodies neutralizing the key STa without cross-reacting with guanylin and uroguanylin, two important ligands controlling homeostasis in human intestinal and renal epithelial cells. In this study, we generated nontoxic fusion antigens that induced antibodies that neutralize STa enterotoxicity in vitro and do not cross-react with guanylin or uroguanylin. These fusions have become the preferred antigens for the development of ETEC vaccines to potentially prevent the deaths of hundreds of thousands of young children and hundreds of millions of diarrheal cases each year.

Capsular genotype and lipooligosaccharide locus class distribution in Campylobacter jejuni from young children with diarrhea and asymptomatic carriers in Bangladesh

Campylobacter jejuni-related diarrheal diseases is one of the major health issues among young children (0-59 months old) in low-income countries. Monitoring of the capsular (capsule polysaccharide, CPS) types of virulent C. jejuni strains in regions where the disease is endemic is of great importance for the development of a customized capsule-based multivalent vaccine. Therefore, we aimed to determine the prevalence of CPS genotypes among C. jejuni strains isolated from young children with enteritis (n = 152) and asymptomatic carriers matched by age, sex, and residence defined as the control group (n = 215) in Bangladesh. CPS genotyping was performed using a newly established multiplex polymerase chain reaction (PCR) method and lipooligosaccharide (LOS) locus classes (A-E) were characterized using PCR as well. We identified 24 different CPS genotypes among the 367 isolates. Four prevalent capsular types, HS5/31 complex (n = 27, 18%), HS3 (n = 26, 17%), HS4A (n = 10, 7%), and HS8/17 (n = 10, 7%) covered almost 50% of the strains from enteritis patients and 43% of the isolates from controls. In combination, the CPS genotype and LOS class was not discriminative between cases and controls. Dominant capsular types previously identified in C. jejuni strains isolated from patients with Guillain-Barré syndrome in Bangladesh were rarely detected in strains isolated from the young children. A similar distribution was evident among enteritis- and control-related strains when comparison was done between CPS types and LOS classes. This is the first systematic study presenting the distribution of CPS genotypes of C. jejuni strains isolated in Bangladesh from children with diarrhea and controls, with capsular genotypes HS5/31 complex, HS3, HS4A, and HS8/17 being prevalent in both. In conclusion, systematic studies are required to develop a multivalent capsule-based vaccine for children in low-income countries.

Enteric Infections in Young Children are Associated with Environmental Enteropathy and Impaired Growth

OBJECTIVE

To investigate the relationship between faecal contamination in child play spaces, enteric infections, environmental enteropathy (EE) and impaired growth among young children.

METHODS

A prospective cohort study was conducted of 203 children 6-30 months of age in rural Bangladesh. Stool samples were analysed by quantitative PCR for Shigella, Enterotoxigenic Escherichia coli (ETEC), Campylobacter jejuni, Giardia intestinalis and Cryptosporidium spp. Four faecal markers of intestinal inflammation were also measured: alpha-1-antitrypsin, myeloperoxidase, neopterin and calprotectin. Child growth was measured at baseline and 9 months after enrolment. E. coli was measured in soil in child play spaces.

RESULTS

Forty-seven percent of study children had three or more enteric pathogens in their stool. Thirty five percent (71/203) of children had Shigella, 30% (61/203) had ETEC, 73% (148/203) had C. jejuni, 79% (160/203) had Giardia intestinalis and none had Cryptosporidium. Children with ETEC had significantly higher calprotectin concentrations (Coefficient: 1.35, 95% Confidence Interval [CI]: 1.005, 1.82). Children with Shigella had a significantly higher odds of being stunted at our 9-month follow-up (OR: 2.01, 95% CI: 1.02, 3.93). Children with Giardia intestinalis had significantly higher E.coli counts in the soil collected from their play spaces (OR: 1.23, 95% CI: 1.02, 1.48).

CONCLUSION

Enteric infections were significantly associated with EE and impaired growth in rural Bangladesh. These findings provide further evidence to support the hypothesis that contaminated soil in child play spaces can lead to enteric infections, many of which are likely subclinical, resulting in EE and impaired growth in young children.

A Hospital-based Case-control Study of Diarrhea in Children in Shanghai

BACKGROUND

Prevention and control of childhood diarrhea is a global priority. We conducted a case-control study of childhood diarrhea in Shanghai.

METHODS

We prospectively recruited diarrheal children in an outpatient setting. Nondiarrheal controls were individually matched to cases. Rotavirus, norovirus and bacterial pathogens were examined. Clinical and epidemiologic data were obtained at enrollment and follow-up.

RESULTS

Potential pathogens identified in 680 diarrheal cases and 680 controls were rotavirus (19.0% vs. 1.3%), norovirus (13.4% vs. 4.7%), nontyphoidal Salmonella (9.3% vs. 1.9%), enteropathogenic Escherichia coli (8.4% vs. 6.9%) and enteroaggregative Escherichia coli (7.2% vs. 6.2%) and Campylobacter (5.1% vs. 1.2%), enterotoxigenic Escherichia coli (1.2% vs. 0.6%), enterohemorrhagic Escherichia coli (0.3% vs. 0%) and Shigella (0.15% vs. 0%), respectively. The specificity and sensitivity of fecal leukocytes >5 per high-power field for the diagnosis of bacterial diarrhea were 94.2% and 22.8%. Salmonella were susceptible to ciprofloxacin, ceftriaxone and amoxicillin-clavulanate and showed low frequency of resistance to azithromycin. Campylobacter showed low frequency of resistance to azithromycin and high frequency of resistance to ciprofloxacin. Diarrheagenic Escherichia coli was highly susceptible to ciprofloxacin and amoxicillin-clavulanate. Contact with diarrheal patients was a risk factor for rotavirus [adjusted odds ratio (aOR): 11.7], norovirus (aOR: 7.5) and Campylobacter (aOR: 27.1) infections. Mother's education was positively associated with Salmonella infection (aOR: 2.1). Good hand hygiene was protective against rotavirus (aOR: 0.6), norovirus (aOR: 0.5) and Salmonella (aOR: 0.3) infections.

CONCLUSIONS

Rotavirus, norovirus, nontyphoidal Salmonella and Campylobacter are significantly associated with diarrhea in Chinese children. Fecal leukocytes >5 per high-power field can predict bacterial diarrhea. Target prevention and appropriate treatment of diarrhea should consider the potential pathogen and resistance pattern.

Genetic fusion protein 3×STa-ovalbumin is an effective coating antigen in ELISA to titrate anti-STa antibodies

Heat-stable toxin type I (STa)-ovalbumin chemical conjugates are currently used as the only coating antigen in ELISA to titrate anti-STa antibodies for ETEC vaccine candidates. STa-ovalbumin chemical conjugation requires STa toxin purification, a process that can be carried out by only a couple of laboratories and often with a low yield. Alternative ELISA coating antigens are needed for anti-STa antibody titration for ETEC vaccine development. In the present study, we genetically fused STa toxin gene (three copies) to a modified chicken ovalbumin gene for genetic fusion 3×STa-ovalbumin, and examined application of this fusion protein as an alternative coating antigen of anti-STa antibody titration ELISA. Data showed fusion protein 3×STa-ovalbumin was effectively expressed and extracted, and anti-STa antibody titration ELISA using this recombinant protein (25 ng per well) or STa-ovalbumin chemical conjugates (10 ng/well) showed the same levels of sensitivity and specificity. Furthermore, mice immunized with this fusion protein developed anti-STa antibodies; induced antibodies showed in vitro neutralization activity against STa toxin. These results indicate that recombinant fusion protein 3×STa-ovalbumin is an effective ELISA coating antigen for anti-STa antibody titration, enabling a reliable reagent supply to make standardization of STa antibody titration assay feasible and to accelerate ETEC vaccine development.

Clonality, virulence and antimicrobial resistance of enteroaggregative Escherichia coli from Mirzapur, Bangladesh

Purpose

This study investigates the virulence and antimicrobial resistance in association with common clonal complexes (CCs) of enteroaggregative Escherichia coli (EAEC) isolated from Bangladesh. The aim was to determine whether specific CCs were more likely to be associated with putative virulence genes and/or antimicrobial resistance.

Methodology

The presence of 15 virulence genes (by PCR) and susceptibility to 18 antibiotics were determined for 151 EAEC isolated from cases and controls during an intestinal infectious disease study carried out between 2007–2011 in the rural setting of Mirzapur, Bangladesh (Kotloff KL, Blackwelder WC, Nasrin D, Nataro JP, Farag TH et al.Clin Infect Dis 2012;55:S232–S245). These data were then analysed in the context of previously determined serotypes and clonal complexes defined by multi-locus sequence typing.

Results

Overall there was no association between the presence of virulence or antimicrobial resistance genes in isolates of EAEC from cases versus controls. However, when stratified by clonal complex (CC) one CC associated with cases harboured more virulence factors (CC40) and one CC harboured more resistance genes (CC38) than the average. There was no direct link between the virulence gene content and antibiotic resistance. Strains within a single CC had variable virulence and resistance gene content indicating independent and multiple gene acquisitions over time.

Conclusion

In Bangladesh, there are multiple clonal complexes of EAEC harbouring a variety of virulence and resistance genes. The emergence of two of the most successful clones appeared to be linked to either increased virulence (CC40) or antimicrobial resistance (CC38), but increased resistance and virulence were not found in the same clonal complexes.

Estimating global, regional and national rotavirus deaths in children aged <5 years: Current approaches, new analyses and proposed improvements

BACKGROUND

Rotavirus is a leading cause of diarrhoeal mortality in children but there is considerable disagreement about how many deaths occur each year.

METHODS AND FINDINGS

We compared CHERG, GBD and WHO/CDC estimates of age under 5 years (U5) rotavirus deaths at the global, regional and national level using a standard year (2013) and standard list of 186 countries. The global estimates were 157,398 (CHERG), 122,322 (GBD) and 215,757 (WHO/CDC). The three groups used different methods: (i) to select data points for rotavirus-positive proportions; (ii) to extrapolate data points to individual countries; (iii) to account for rotavirus vaccine coverage; (iv) to convert rotavirus-positive proportions to rotavirus attributable fractions; and (v) to calculate uncertainty ranges. We conducted new analyses to inform future estimates. We found that acute watery diarrhoea was associated with 87% (95% CI 83-90%) of U5 diarrhoea hospitalisations based on data from 84 hospital sites in 9 countries, and 65% (95% CI 57-74%) of U5 diarrhoea deaths based on verbal autopsy reports from 9 country sites. We reanalysed data from the Global Enteric Multicenter Study (GEMS) and found 44% (55% in Asia, and 32% in Africa) rotavirus-positivity among U5 acute watery diarrhoea hospitalisations, and 28% rotavirus-positivity among U5 acute watery diarrhoea deaths. 97% (95% CI 95-98%) of the U5 diarrhoea hospitalisations that tested positive for rotavirus were entirely attributable to rotavirus. For all clinical syndromes combined the rotavirus attributable fraction was 34% (95% CI 31-36%). This increased by a factor of 1.08 (95% CI 1.02-1.14) when the GEMS results were reanalysed using a more sensitive molecular test.

CONCLUSIONS

We developed consensus on seven proposals for improving the quality and transparency of future rotavirus mortality estimates.

Use of Serologic Responses against Enteropathogens to Assess the Impact of a Point-of-Use Water Filter: A Randomized Controlled Trial in Western Province, Rwanda

Diarrhea is a leading contributor to childhood morbidity and mortality in sub-Saharan Africa. Given the challenge of blinding most water, sanitation, and hygiene (WASH) interventions, diarrheal disease outcome measures in WASH intervention trials are subject to potential bias and misclassification. Using the platform of a cluster-randomized controlled trial of a household-based drinking water filter in western province, Rwanda, we assessed the impact of the drinking water filter on enteric seroconversion in young children as a health outcome and examined the association between serologic responses and caregiver-reported diarrhea. Among the 2,179 children enrolled in the trial, 189 children 6-12 months of age were enrolled in a nested serology study. These children had their blood drawn at baseline and 6-12 months after the intervention was distributed. Multiplex serologic assays for Giardia, Cryptosporidium, Entamoeba histolytica, norovirus, Campylobacter, enterotoxigenic Escherichia coli and Vibrio cholerae were performed. Despite imperfect uptake, receipt of the water filter was associated with a significant decrease in seroprevalence of IgG directed against Cryptosporidium parvum Cp17 and Cp23 (relative risk [RR]: 0.62, 95% confidence interval [CI]: 0.44-0.89). Serologic responses were positively associated with reported diarrhea in the previous 7 days for both Giardia intestinalis (RR: 1.94, 95% CI: 1.04-3.63) and C. parvum (RR: 2.21, 95% CI: 1.09-4.50). Serologic responses for all antigens generally increased in the follow-up round, rising sharply after 12 months of age. The water filter is associated with reduced serologic responses against C. parvum, a proxy for exposure and infection; therefore, serologic responses against protozoa may be a suitable health outcome measure for WASH trials among children with diarrhea.

MEFA (multiepitope fusion antigen)-Novel Technology for Structural Vaccinology, Proof from Computational and Empirical Immunogenicity Characterization of an Enterotoxigenic Escherichia coli (ETEC) Adhesin MEFA

Vaccine development often encounters the challenge of virulence heterogeneity. Enterotoxigenic Escherichia coli (ETEC) bacteria producing immunologically heterogeneous virulence factors are a leading cause of children's diarrhea and travelers' diarrhea. Currently, we do not have licensed vaccines against ETEC bacteria. While conventional methods continue to make progress but encounter challenge, new computational and structure-based approaches are explored to accelerate ETEC vaccine development. In this study, we applied a structural vaccinology concept to construct a structure-based multiepitope fusion antigen (MEFA) to carry representing epitopes of the seven most important ETEC adhesins [CFA/I, CFA/II (CS1-CS3), CFA/IV (CS4-CS6)], simulated antigenic structure of the CFA/I/II/IV MEFA with computational atomistic modeling and simulation, characterized immunogenicity in mouse immunization, and examined the potential of structure-informed vaccine design for ETEC vaccine development. A tag-less recombinant MEFA protein (CFA/I/II/IV MEFA) was effectively expressed and extracted. Molecular dynamics simulations indicated that this MEFA immunogen maintained a stable secondary structure and presented epitopes on the protein surface. Empirical data showed that mice immunized with the tagless CFA/I/II/IV MEFA developed strong antigen-specific antibody responses, and mouse serum antibodies significantly inhibited in vitro adherence of bacteria expressing these seven adhesins. These results revealed congruence of antigen immunogenicity between computational simulation and empirical mouse immunization and indicated this tag-less CFA/I/II/IV MEFA potentially an antigen for a broadly protective ETEC vaccine, suggesting a potential application of MEFA-based structural vaccinology for vaccine design against ETEC and likely other pathogens.

Identification of Subsets of Enteroaggregative Escherichia coli Associated with Diarrheal Disease among Under 5 Years of Age Children from Rural Gambia

Enteroaggregative Escherichia coli (EAEC) cause acute and persistent diarrhea, mostly in children worldwide. Outbreaks of diarrhea caused by EAEC have been described, including a large outbreak caused by a Shiga toxin expressing strain. This study investigated the association of EAEC virulence factors with diarrhea in children less than 5 years. We characterized 428 EAEC strains isolated from stool samples obtained from moderate-to-severe diarrhea cases (157) and healthy controls (217) children aged 0–59 months recruited over 3 years as part of the Global Enteric Multicenter Study (GEMS) in The Gambia. Four sets of multiplex polymerase chain reaction were applied to detect 21 EAEC-virulence genes from confirmed EAEC strains that target pCVD432 (aatA) and AAIC (aaiC). In addition, Kirby-Bauer disc diffusion antimicrobial susceptibility testing was performed on 88 EAEC strains following Clinical Laboratory Standard Institute guidelines. We observed that the plasmid-encoded enterotoxin [odds ratio (OR): 6.9, 95% confidence interval (CI): 2.06–29.20, P < 0.001], aggregative adherence fimbriae/I fimbriae (aggA) [OR: 2.2, 95% CI: 1.16–4.29, P = 0.008], and hexosyltransferase (capU) [OR: 1.9, 95% CI 1.02–3.51, P = 0.028] were associated with moderate-to-severe diarrhea among children < 12 months old but not in the older age strata (> 12 months). Our data suggest that some EAEC-virulent factors have age-specific associations with moderate-to-severe diarrhea in infants. Furthermore, our study showed that 85% and 72% of EAEC strains tested were resistant to sulphamethoxazole-trimethoprim and ampicillin, respectively. Sulphamethoxazole-trimethoprim and ampicillin are among the first-line antibiotics used for the treatment of diarrhea in The Gambia.

Intravenous rehydration of malnourished children with acute gastroenteritis and severe dehydration: A systematic review

Background: Rehydration strategies in children with severe acute malnutrition (SAM) and severe dehydration are extremely cautious. The World Health Organization (WHO) SAM guidelines advise strongly against intravenous fluids unless the child is shocked or severely dehydrated and unable to tolerate oral fluids. Otherwise, guidelines recommend oral or nasogastric rehydration using low sodium oral rehydration solutions. There is limited evidence to support these recommendations.

Methods: We conducted a systematic review of randomised controlled trials (RCTs) and observational studies on 15 ^th June 2017 comparing different strategies of rehydration therapy in children with acute gastroenteritis and severe dehydration, specifically relating to intravenous rehydration, using standard search terms. Two authors assessed papers for inclusion. The primary endpoint was evidence of fluid overload.

Results: Four studies were identified, all published in English, including 883 children, all of which were conducted in low resource settings. Two were randomised controlled trials and two observational cohort studies, one incorporated assessment of myocardial and haemodynamic function. There was no evidence of fluid overload or other fluid-related adverse events, including children managed on more liberal rehydration protocols. Mortality was high overall, and particularly in children with shock managed on WHO recommendations (day-28 mortality 82%). There was no difference in safety outcomes when different rates of intravenous rehydration were compared.

Conclusions: The current ‘strong recommendations’ for conservative rehydration of children with SAM are not based on emerging evidence. We found no clinical trials providing a direct assessment of the current WHO guidelines, and those that were available suggested that these children have a high mortality and remain fluid depleted on current therapy. Recent studies have reported no evidence of fluid overload or heart failure with more liberal rehydration regimens. Clinical trials are urgently required to inform guidelines on routes and rates of intravenous rehydration therapy for dehydration in children with SAM.

Clinical features and molecular epidemiology of diarrheagenic Escherichia coli pathotypes identified by fecal gastrointestinal multiplex nucleic acid amplification in patients with cancer and diarrhea

Diarrheagenic Escherichia coli (DEC) pathotypes with differing epidemiology and clinical features, are known causes of disease with worldwide occurrence. At a major cancer center in the U.S., we studied patients with cancer and diarrhea for whom a GI Biofire FilmArray multiplex GI panel (BFM) was performed. An enteropathogen was identified in 382 of 2017 (19%) samples distributed across 311 patients. Of these, 60/311(19%) were positive for DEC. Patients receiving hematopoietic stem cell transplants (HSCT) 29/60 (48%) or with a hematologic malignancy 17/60 (28%) accounted for the majority of DEC cases. Enteropathogenic E. coli (EPEC, n=35 [58%]), enteroaggregative E. coli (EAEC, n=10 [17%]) and Shiga toxin producing E. coli (STEC, n=3 [5%]) were the most common DEC identified and peaked in the summer months. Stool cultures confirmed infections in 6/10 (60%) EAEC (five typical AggR⁺), and EPEC was recovered in 8/35 (22%) samples (all atypical eaeA⁺, bfp^-). DEC was identified in 22 cases (37%) that developed diarrhea >48hours after admission suggesting health care acquisition. Chronic infections were found in 2 EPEC and 1 EAEC cases that were tested at 1month or beyond with shedding that ranged from 58 to >125days. Two patients that underwent hematopoietic stem cell transplantation carried EAEC strains resistant to multiple antibiotics including fluoroquinolones and expressed extended spectrum beta lactamases. While in some instances BFM results were not verified in culture and could represent false positives, DEC pathotypes, especially EPEC and EAEC, caused chronic infections with antimicrobial-resistant strains in a subset of immunosuppressed cancer patients.

Gastroenteritis Aggressive Versus Slow Treatment For Rehydration (GASTRO). A pilot rehydration study for severe dehydration: WHO plan C versus slower rehydration

Background: The World Health Organization (WHO) rehydration management guidelines (Plan C) for children with acute gastroenteritis (AGE) and severe dehydration are widely practiced in resource-poor settings, yet have never been formally evaluated in a clinical trial. A recent audit of outcome of AGE at Kilifi County Hospital, Kenya noted that 10% of children required high dependency care (20% mortality) and a number developed fluid-related complications. The fluid resuscitation trial, FEAST, conducted in African children with severe febrile illness, demonstrated higher mortality with fluid bolus therapy and raised concerns regarding the safety of rapid intravenous rehydration therapy. Those findings warrant a detailed physiological study of children’s responses to rehydration therapy incorporating quantification of myocardial performance and haemodynamic changes. 

Methods: GASTRO is a multi-centre, unblinded Phase II randomised controlled trial of 120 children aged 2 months to 12 years admitted to hospital with severe dehydration secondary to AGE. Children with severe malnutrition, chronic diarrhoea and congenital/rheumatic heart disease are excluded. Children will be enrolled over 18 months in 3 centres in Kenya and Uganda and followed until 7 days post-discharge. The trial will randomise children 1:1 to standard rapid rehydration using Ringers Lactate  (WHO plan ‘C’ – 100mls/kg over 3-6 hours according to age, plus additional 0.9% saline boluses for children presenting in shock) or to a slower rehydration regimen (100mls/kg given over 8 hours and without the addition of fluid boluses). Enrolment started in November 2016 and is on-going. Primary outcome is frequency of adverse events, particularly related to cardiovascular compromise and neurological sequelae.  Secondary outcomes focus on clinical, biochemical, and physiological measures related to assessment of severity of dehydration, and response to treatment by intravenous rehydration.

Discussion: Results from this pilot will contribute to generating robust definitions of outcomes (in particular for non-mortality endpoints) for a larger Phase III trial.

Animal-related factors associated with moderate-to-severe diarrhea in children younger than five years in western Kenya: A matched case-control study

BACKGROUND

Diarrheal disease remains among the leading causes of global mortality in children younger than 5 years. Exposure to domestic animals may be a risk factor for diarrheal disease. The objectives of this study were to identify animal-related exposures associated with cases of moderate-to-severe diarrhea (MSD) in children in rural western Kenya, and to identify the major zoonotic enteric pathogens present in domestic animals residing in the homesteads of case and control children.

METHODOLOGY/PRINCIPAL FINDINGS

We characterized animal-related exposures in a subset of case and control children (n = 73 pairs matched on age, sex and location) with reported animal presence at home enrolled in the Global Enteric Multicenter Study in western Kenya, and analysed these for an association with MSD. We identified potentially zoonotic enteric pathogens in pooled fecal specimens collected from domestic animals resident at children's homesteads. Variables that were associated with decreased risk of MSD were washing hands after animal contact (matched odds ratio [MOR] = 0.2; 95% CI 0.08-0.7), and presence of adult sheep that were not confined in a pen overnight (MOR = 0.1; 0.02-0.5). Variables that were associated with increased risk of MSD were increasing number of sheep owned (MOR = 1.2; 1.0-1.5), frequent observation of fresh rodent excreta (feces/urine) outside the house (MOR = 7.5; 1.5-37.2), and participation of the child in providing water to chickens (MOR = 3.8; 1.2-12.2). Of 691 pooled specimens collected from 2,174 domestic animals, 159 pools (23%) tested positive for one or more potentially zoonotic enteric pathogens (Campylobacter jejuni, C. coli, non-typhoidal Salmonella, diarrheagenic E. coli, Giardia, Cryptosporidium, or rotavirus). We did not find any association between the presence of particular pathogens in household animals, and MSD in children.

CONCLUSIONS AND SIGNIFICANCE

Public health agencies should continue to promote frequent hand washing, including after animal contact, to reduce the risk of MSD. Future studies should address specific causal relations of MSD with sheep and chicken husbandry practices, and with the presence of rodents.

The Burden and Etiology of Diarrheal Illness in Developing Countries

Reductions in mortality from diarrheal diseases among young children have occurred in recent decades; however, approximately 500,000 children continue to die each year. Moreover, similar reductions in disease incidence have not been seen, episodes that impact the growth and development of young children. Two recent studies, MAL-ED and GEMS, have more clearly defined the burden and cause of diarrhea among young children, identifying four leading pathogens: rotavirus, CryptosporidiumShigella, and heat stable toxin-producing enterotoxigenic Escherichia coli. Global introduction of rotavirus vaccine is poised to substantially reduce the incidence of rotavirus infection. Interventions are needed to reduce the burden that remains.

Factors Associated with the Duration of Moderate-to-Severe Diarrhea among Children in Rural Western Kenya Enrolled in the Global Enteric Multicenter Study, 2008-2012

Diarrheal disease is a leading cause of death among young children worldwide. As rates of acute diarrhea (AD; 1-6 days duration) have decreased, persistent diarrhea (PD; > 14 days duration) accounts for a greater proportion of the diarrheal disease burden. We describe factors associated with the duration of moderate-to-severe diarrhea in Kenyan children < 5 years old enrolled in the Global Enteric Multicenter Study. We found 587 (58%) children experienced AD, 360 (35%) had prolonged acute diarrhea (ProAD; 7-13 days duration), and 73 (7%) had PD. We constructed a Cox proportional hazards model to identify factors associated with diarrheal duration. Risk factors independently associated with longer diarrheal duration included infection with Cryptosporidium (hazard ratio [HR]: 0.868, P = 0.035), using an unimproved drinking water source (HR: 0.87, P = 0.035), and being stunted at enrollment (HR: 0.026, P < 0.0001). Diarrheal illness of extended duration appears to be multifactorial; given its association with adverse health and development outcomes, effective strategies should be implemented to reduce the duration and severity of diarrheal illness. Effective treatments for Cryptosporidium should be identified, interventions to improve drinking water are imperative, and nutrition should be improved through exclusive breastfeeding in infants ≤ 6 months and appropriate continued feeding practices for ill children.

Global burden of diarrheal diseases among children in developing countries: Incidence, etiology, and insights from new molecular diagnostic techniques

The Global Enteric Multicenter Study (GEMS) demonstrated that Shigella and enterotoxigenic Escherichia coli (ETEC) producing heat stable toxin (ST) (either alone or in combination with heat labile toxin) are among the most important pathogens associated with moderate-to-severe diarrhea (MSD) in children younger than 5years of age living in developing countries. To inform the design of vaccines and other interventions, we reviewed published data and new results from GEMS characterizing the burden of Shigella and ST-ETEC infections. Clinical parameters were assessed to examine the value of various case definitions as indicators of MSD associated with Shigella and ST-ETEC for use in clinical trials. We discussed advantages and disadvantages of culture-based and culture-independent molecular diagnostics for detecting clinically and epidemiologically relevant disease. Shigella serotyping data from GEMS were examined to identify desirable components of Shigella and ETEC vaccines likely to confer broad protection. These findings can inform the development and implementation of vaccines to prevent these important infections among infants and children in developing countries.

Transcriptional Variation of Diverse Enteropathogenic Escherichia coli Isolates under Virulence-Inducing Conditions

Enteropathogenic Escherichia coli (EPEC) bacteria are a diverse group of pathogens that cause moderate to severe diarrhea in young children in developing countries. EPEC isolates can be further subclassified as typical EPEC (tEPEC) isolates that contain the bundle-forming pilus (BFP) or as atypical EPEC (aEPEC) isolates that do not contain BFP. Comparative genomics studies have recently highlighted the considerable genomic diversity among EPEC isolates. In the current study, we used RNA sequencing (RNA-Seq) to characterize the global transcriptomes of eight tEPEC isolates representing the identified genomic diversity, as well as one aEPEC isolate. The global transcriptomes were determined for the EPEC isolates under conditions of laboratory growth that are known to induce expression of virulence-associated genes. The findings demonstrate that unique genes of EPEC isolates from diverse phylogenomic lineages contribute to variation in their global transcriptomes. There were also phylogroup-specific differences in the global transcriptomes, including genes involved in iron acquisition, which had significant differential expression in the EPEC isolates belonging to phylogroup B2. Also, three EPEC isolates from the same phylogenomic lineage (EPEC8) had greater levels of similarity in their genomic content and exhibited greater similarities in their global transcriptomes than EPEC from other lineages; however, even among closely related isolates there were isolate-specific differences among their transcriptomes. These findings highlight the transcriptional variability that correlates with the previously unappreciated genomic diversity of EPEC. IMPORTANCE Recent studies have demonstrated that there is considerable genomic diversity among EPEC isolates; however, it is unknown if this genomic diversity leads to differences in their global transcription. This study used RNA-Seq to compare the global transcriptomes of EPEC isolates from diverse phylogenomic lineages. We demonstrate that there are lineage- and isolate-specific differences in the transcriptomes of genomically diverse EPEC isolates during growth under in vitro virulence-inducing conditions. This study addressed biological variation among isolates of a single pathovar in an effort to demonstrate that while each of these isolates is considered an EPEC isolate, there is significant transcriptional diversity among members of this pathovar. Future studies should consider whether this previously undescribed transcriptional variation may play a significant role in isolate-specific variability of EPEC clinical presentations.

Shigella depends on SepA to destabilize the intestinal epithelial integrity via cofilin activation

Shigella is unique among enteric pathogens, as it invades colonic epithelia through the basolateral pole. Therefore, it has evolved the ability to breach the intestinal epithelial barrier to deploy an arsenal of effector proteins, which permits bacterial invasion and leads to a severe inflammatory response. However, the mechanisms used by Shigella to regulate epithelial barrier permeability remain unknown. To address this question, we used both an intestinal polarized model and a human ex-vivo model to further characterize the early events of host-bacteria interactions. Our results showed that secreted Serine Protease A (SepA), which belongs to the serine protease autotransporter of Enterobacteriaceae family, is responsible for critically disrupting the intestinal epithelial barrier. Such disruption facilitates bacterial transit to the basolateral pole of the epithelium, ultimately fostering the hallmarks of the disease pathology. SepA was found to cause a decrease in active LIM Kinase 1 (LIMK1) levels, a negative inhibitor of actin-remodeling proteins, namely cofilin. Correspondingly, we observed increased activation of cofilin, a major actin-polymerization factor known to control opening of tight junctions at the epithelial barrier. Furthermore, we resolved the crystal structure of SepA to elucidate its role on actin-dynamics and barrier disruption. The serine protease activity of SepA was found to be required for the regulatory effects on LIMK1 and cofilin, resulting in the disruption of the epithelial barrier during infection. Altogether, we demonstrate that SepA is indispensable for barrier disruption, ultimately facilitating Shigella transit to the basolateral pole where it effectively invades the epithelium.

Comparative genomics and transcriptomics of Escherichia coli isolates carrying virulence factors of both enteropathogenic and enterotoxigenic E. coli

Escherichia coli that are capable of causing human disease are often classified into pathogenic variants (pathovars) based on their virulence gene content. However, disease-associated hybrid E. coli, containing unique combinations of multiple canonical virulence factors have also been described. Such was the case of the E. coli O104:H4 outbreak in 2011, which caused significant morbidity and mortality. Among the pathovars of diarrheagenic E. coli that cause significant human disease are the enteropathogenic E. coli (EPEC) and enterotoxigenic E. coli (ETEC). In the current study we use comparative genomics, transcriptomics, and functional studies to characterize isolates that contain virulence factors of both EPEC and ETEC. Based on phylogenomic analysis, these hybrid isolates are more genomically-related to EPEC, but appear to have acquired ETEC virulence genes. Global transcriptional analysis using RNA sequencing, demonstrated that the EPEC and ETEC virulence genes of these hybrid isolates were differentially-expressed under virulence-inducing laboratory conditions, similar to reference isolates. Immunoblot assays further verified that the virulence gene products were produced and that the T3SS effector EspB of EPEC, and heat-labile toxin of ETEC were secreted. These findings document the existence and virulence potential of an E. coli pathovar hybrid that blurs the distinction between E. coli pathovars.

Development of live attenuated bacterial vaccines targeting Escherichia coli heat-labile and heat-stable enterotoxins

Enterotoxigenic Escherichia coli (ETEC), defined by the production of heat labile (LT) and/or heat stable (ST) toxins, are major causes of diarrhea in animals, children in developing countries and to travelers. No broadly protective ETEC vaccine is available, largely because of the difficulty in inducing immunity to the small ST molecule. To take advantage of the demonstration (Liu et al., 2011; Zhang et al., 2013, 2010) that genetically produced fusions of mutant ST with LT subunits can induce effective immunity against both toxins, we engineered a live attenuated vaccine vector strain of E. coli (ZCR533), expressing the immunogenic LT-ST fusions. To present the LT-ST fusions to the mucosal immune system, we used restriction-free cloning to incorporate them into the passenger domain of the autotransporter protein (EspP) expressed on a medium copy number plasmid. This versatile system permits expression of incorporated antigens in either surface-bound or secreted forms by the ZCR533 vector, for delivery to the mucosal inductive sites. Incorporation of the fusions into EspP plasmids was confirmed by PCR and DNA sequencing. Protein expression was confirmed by Western blot of whole cell lysates and culture supernatents using polyclonal antisera to LT. Expression of the surface-targeted fusion on the surface of ZCR533 was confirmed by immuno-fluorescent staining. These studies show that antigenic LT-ST fusions can be surface-expressed or secreted, by our attenuated E. coli ZCR533 vaccine vector via the EspP autotransporter. These constructs could serve as broadly protective vaccine candidates to protect against both LT- and ST-producing ETEC.

Predictors of diarrheal mortality and patterns of caregiver health seeking behavior in in Karachi, Pakistan

Background

Pakistan is unfortunately among the five countries that contributed to the most deaths due to diarrhea and pneumonia in 2010. To explore factors associated with diarrheal deaths we assessed care–seeking behavior and other predictors of diarrhea–related mortality in children in selected low–income peri–urban communities of Karachi, Pakistan.

Methods

A mixed methods study (qualitative and quantitative) using matched case–control design and focus group discussions with parents of children with moderate to severe diarrhea (MSD) was undertaken. Cases were children  <5 years of age who died within 60 days of developing an episode of MSD. Controls were age–matched children who survived after 60 days of an episode of MSD. Demographic, clinical, and care–related behavioral predictors of mortality were assessed. Conditional logistic regression was performed, matched adjusted odds ratios (mOR) are reported.

Results

Parents of 77 cases and 154 controls were interviewed. Cases were less likely to receive appropriate care compared to controls (mOR = 0.2, 95% confidence interval (CI) 0.05–0.91). Refusal for hospital admission (OR = 8.9, 95% CI 2.6–30.8), and delays in reaching the health facility (OR = 3.6, 95% CI 1.0–12.9) were significant independent predictors of mortality. We found strong beliefs in traditional and spiritual healing in the population; use of both modern and traditional/spiritual treatments concurrently was common.

Conclusion

Appropriate care seeking behavior predicts survival in children with diarrhea in Pakistan. There is a complex belief system relating to traditional and standard therapies. Health education for appropriate health care seeking should be implemented in order to achieve a substantial decline in diarrheal disease mortality in Pakistan.

Multiple etiologies of infectious diarrhea and concurrent infections in a pediatric outpatient-based screening study in Odisha, India

BACKGROUND

There are multiple etiologies responsible for infectious gastroenteritis causing acute diarrhea which are often under diagnosed. Also acute diarrhea is one of the major causes of morbidity and mortality among children less than 5 years of age.

METHODS

In our study, fecal samples (n = 130) were collected from children (<5 years) presenting with symptoms of acute diarrhea. Samples were screened for viral, bacterial, and parasitic etiologies. Rotavirus and Adenovirus were screened by immunochromatographic tests. Diarrheagenic Escherichia coli (EPEC, EHEC, STEC, EAEC, O157, O111), Shigella spp., Salmonella spp., Vibrio cholera, Cryptosporidium spp., and Giardia spp. were detected by gene-specific polymerase chain reaction.

RESULTS

Escherichia coli was detected to be the major etiological agent (30.07%) followed by Rotavirus (26.15%), Shigella (23.84%), Adenovirus (4.61%), Cryptosporidium (3.07%), and Giardia (0.77%). Concurrent infections with two or more pathogens were observed in 44 of 130 (33.84%) cases with a predominant incidence particularly in <2-year-old children (65.90%) compared to children of 2-5 years age group (34.09%). An overall result showed significantly higher detection rates among children with diarrhea in both combinations of two as well as three infections concurrently (p = 0.004915 and 0.03917, respectively).

CONCLUSION

Suspecting possible multiple infectious etiologies and diagnosis of the right causative agent(s) can aid in a better pharmacological management of acute childhood diarrhea. It is hypothesized that in cases with concurrent infections the etiological agents might be complementing each other's strategies of pathogenesis resulting in severe diarrhea that could be studied better in experimental infections.

Typical & atypical enteropathogenic Escherichia coli in diarrhoea & their role as carrier in children under five

BACKGROUND & OBJECTIVES

Multidrug-resistant enteropathogenic Escherichia coli (EPEC) is responsible for a large number of cases of infantile diarrhoea in developing countries, causing failure in treatment with consequent health burden and resulting in a large number of deaths every year. This study was undertaken to determine the proportion of typical and atypical EPEC in under five children with diarrhoea and controls, their function as a carriage and to identify virulent genes associated with them.

METHODS

During the study period, 120 stool samples including 80 from controls children were collected and analyzed for the presence of EPEC using standard bacteriological methods. Isolates were subjected to antimicrobial testing by disc diffusion method. Isolates confirmed as E. coli by phenotypic method were further tested for the presence of attaching and effacing (eae) and bundle-forming pilus (bfpA) genes by real-time SYBR Green-based polymerase chain reaction.

RESULTS

All isolates were tested for the presence of EPEC. The frequency of typical EPEC was 20 and 16.25 per cent whereas the frequency of atypical EPEC strains was 5 and 23.75 per cent in patients and controls, respectively (PbfpA was seen in 45 and 18.75 per cent isolates of diarrhoeal patients and controls, respectively.

INTERPRETATION & CONCLUSIONS

Our results showed that typical EPEC was a common cause of diarrhoea, but at the same time, atypical EPEC was emerging as colonizers in the intestine of children with and without diarrhoea in and around Delhi. Children can be considered asymptomatic carriers of these pathogens and can transmit them to other susceptible children. Adequate steps need to be taken to stop these strains from developing and spreading further.

Passive antibodies derived from intramuscularly immunized toxoid fusion 3xSTaN12S-dmLT protect against STa+ enterotoxigenic Escherichia coli (ETEC) diarrhea in a pig model

Enterotoxigenic Escherichia coli (ETEC) strains are among the most common causes of children's diarrhea and travelers' diarrhea. Developing effective vaccines against ETEC associated diarrhea becomes a top priority. ETEC heat-labile toxin (LT) and heat-stable toxin (STa) toxoid fusion 3xSTa_N12S-dmLT was demonstrated recently to induce neutralizing antitoxin antibodies in intraperitoneally or subcutaneously immunized mice. However, whether antibodies derived from this toxoid fusion are protective against ETEC diarrhea has not been examined. In this study, we intramuscularly immunized pregnant gilts with toxoid fusion 3xSTa_N12S-dmLT, challenged suckling piglets with a STa-positive ETEC strain, and assessed protective efficacy of passive acquire antitoxin antibodies against ETEC diarrhea. Data showed all three immunized gilts developed anti-STa IgG and IgA antibodies, and piglets born to the immunized dams acquired anti-STa and anti-LT antibodies. When challenged with a STa+ ETEC strain, none of the piglets born to the immunized dams developed watery diarrhea, with 20 piglets remained normal and the other 8 piglets developed mild diarrhea indicated with stained butt. In contrast, the control dams and born piglets had no anti-STa or anti-LT antibodies detected, and 26 out 32 piglets developed watery diarrhea after challenge of the STa+ ETEC strain. These results indicated that passive acquired anti-STa antibodies are protective against ETEC diarrhea, and suggested potential application of toxoid fusion 3xSTa_N12S-dmLT in ETEC vaccine development.

Cryptosporidiosis Risk in New Zealand Children Under 5 Years Old is Greatest in Areas with High Dairy Cattle Densities

The public health risks associated with dairy farming intensification are an emerging concern. We examine the association between dairy cattle density and cryptosporidiosis risk in children <5 years old in New Zealand from 1997 to 2008, a period of rapid intensification of the dairy industry. Multi-level Poisson regression was used to model reported cryptosporidiosis (N = 3869 cases) incidence in relation to dairy cattle densities across urban and rural areas separately, after controlling for microbiological quality of public drinking water supplies and neighbourhood socio-economic factors using the Census Area Unit of residence. Within urban areas, the risk of cryptosporidiosis in children less than 5 years old was significantly, positively associated with medium and high dairy cattle density IRR 1.3 (95% CI 1.2, 1.5) and 1.5 (95% CI 1.2, 1.9) respectively, when compared to areas with no dairy cattle. Within rural areas, the incidence risk of cryptosporidiosis in children less than 5 years old were significantly, positively associated with medium and high dairy cattle density: IRR 1.7 (95% CI 1.3, 2.3) and 2.0 (95% CI 1.5, 2.8) respectively, when compared to areas with no dairy cattle. These results have public health implications for children living on and in proximity to intensively stocked dairy cattle farms.

Prevalence, seasonal variation, and antibiotic resistance pattern of enteric bacterial pathogens among hospitalized diarrheic children in suburban regions of central Kenya

Background

The epidemiology of enteric pathogens has not been well studied in Kenya because of wide disparities in health status across the country. Therefore, the present study describes the prevalence of enteropathogenic bacteria, their seasonal variation, and antibiotic resistance profiles among hospitalized diarrheic children in a suburban region of central Kenya.

Methods

Fecal samples were collected between July 2009 and December 2013 from a total of 1410 children younger than 5 years, hospitalized with acute diarrhea in Kiambu County Hospital, Kenya. Conventional culture, biochemical, and molecular methods were conducted to identify causative bacterial pathogens and their virulence factors. Antimicrobial susceptibility tests were performed using E-test strips and VITEK-2 advanced expert system (AES) to evaluate the drug-resistance pattern of the isolates.

Results

Of the 1410 isolates, bacterial infections were identified in 474 cases. Diarrheagenic Escherichia coli (DEC) was the most frequently isolated pathogen (86.5%). Other pathogens such as Aeromonas (5.5%), Shigella (4%), Salmonella (3.4%), Providencia (3.2%), Vibrio spp. (1.1%), Yersinia enterocolitica (1.1%), and Plesiomonas shigelloides (0.2%) were also identified. Mixed bacterial infection was observed among 11.1% of the cases. The highest infection rate was found during the dry season (59.3%, p = 0.04). Most of the DEC was found to be multidrug resistant to trimethoprim/sulfamethoxazole 97.6%, amoxicillin 97.6%, erythromycin 96.9%, ampicillin 96.6%, and streptomycin 89%.

Conclusions

This study suggests that DEC is the leading diarrhea-causing bacterial pathogen circulating in central Kenya, and seasonality has a significant effect on its transmission. Proper antibiotic prescription and susceptibility testing is important to guide appropriate antimicrobial therapy.

Enterotoxigenic Escherichia coli heat-stable toxin and heat-labile toxin toxoid fusion 3xSTaN12S-dmLT induces neutralizing anti-STa antibodies in subcutaneously immunized mice

Enterotoxigenic Escherichia coli (ETEC) bacteria producing heat-stable toxin (STa) and/or heat-labile toxin (LT) are among top causes of children's diarrhea and travelers' diarrhea. Currently no vaccines are available for ETEC associated diarrhea. A major challenge in developing ETEC vaccines is the inability to stimulate protective antibodies against the key STa toxin that is potently toxic and also poorly immunogenic. A recent study suggested toxoid fusion 3xSTaN12S-dmLT, which consists of a monomer LT toxoid (LTR192G/L211A) and three copies of STa toxoid STaN12S, may represent an optimal immunogen inducing neutralizing antibodies against STa toxin [IAI 2014, 82(5):1823-32]. In this study, we immunized mice with this fusion protein following a different parenteral route and using different adjuvants to further characterize immunogenicity of this toxoid fusion. Data from this study showed that 3xSTaN12S-dmLT toxoid fusion induced neutralizing anti-STa antibodies in the mice following subcutaneous immunization, as effectively as in the mice under intraperitoneal route. Data also indicated that double mutant LT (dmLT) can be an effective adjuvant for this toxoid fusion in mice subcutaneous immunization. Results from this study affirmed that toxoid fusion 3xSTaN12S-dmLT induces neutralizing antibodies against STa toxin, suggesting this toxoid fusion is potentially a promising immunogen for ETEC vaccine development.

A Comparison of Diarrheal Severity Scores in the MAL-ED Multisite Community-Based Cohort Study

OBJECTIVES

There is a lack of consensus on how to measure diarrheal severity. Within the context of a multisite, prospective cohort study, we evaluated the performance of a modified Vesikari score (MAL-ED), 2 previously published scores (Clark and CODA [a diarrheal severity score (Community DiarrheA) published by Lee et al]), and a modified definition of moderate-to-severe diarrhea (MSD) based on dysentery and health care worker diagnosed dehydration.

METHODS

Scores were built using maternally reported symptoms or fieldworker-reported clinical signs obtained during the first 7 days of a diarrheal episode. The association between these and the risk of hospitalization were tested using receiver operating characteristic analysis. Severity scores were also related to illness etiology, and the likelihood of the episode subsequently becoming prolonged or persistent.

RESULTS

Of 10,159 episodes from 1681 children, 143 (4.0%) resulted in hospitalization. The area under the curve of each score as a predictor of hospitalization was 0.84 (95% confidence interval: 0.81, 0.87) (Clark), 0.85 (0.82, 0.88) (MAL-ED), and 0.87 (0.84, 0.89) (CODA). Severity was also associated with etiology and episode duration. Although families were more likely to seek care for severe diarrhea, approximately half of severe cases never reached the health system.

CONCLUSIONS

Community-based diarrheal severity scores are predictive of relevant child health outcomes. Because they require no assumptions about health care access or utilization, they are useful in refining estimates of the burden of diarrheal disease, in estimating the effect of disease control interventions, and in triaging children for referral in low- and middle-income countries in which the rates of morbidity and mortality after diarrhea remain high.

Use of quantitative molecular diagnostic methods to identify causes of diarrhoea in children: a reanalysis of the GEMS case-control study

BACKGROUND

Diarrhoea is the second leading cause of mortality in children worldwide, but establishing the cause can be complicated by diverse diagnostic approaches and varying test characteristics. We used quantitative molecular diagnostic methods to reassess causes of diarrhoea in the Global Enteric Multicenter Study (GEMS).

METHODS

GEMS was a study of moderate to severe diarrhoea in children younger than 5 years in Africa and Asia. We used quantitative real-time PCR (qPCR) to test for 32 enteropathogens in stool samples from cases and matched asymptomatic controls from GEMS, and compared pathogen-specific attributable incidences with those found with the original GEMS microbiological methods, including culture, EIA, and reverse-transcriptase PCR. We calculated revised pathogen-specific burdens of disease and assessed causes in individual children.

FINDINGS

We analysed 5304 sample pairs. For most pathogens, incidence was greater with qPCR than with the original methods, particularly for adenovirus 40/41 (around five times), Shigella spp or enteroinvasive Escherichia coli (EIEC) and Campylobactor jejuni o C coli (around two times), and heat-stable enterotoxin-producing E coli ([ST-ETEC] around 1·5 times). The six most attributable pathogens became, in descending order, Shigella spp, rotavirus, adenovirus 40/41, ST-ETEC, Cryptosporidium spp, and Campylobacter spp. Pathogen-attributable diarrhoeal burden was 89·3% (95% CI 83·2-96·0) at the population level, compared with 51·5% (48·0-55·0) in the original GEMS analysis. The top six pathogens accounted for 77·8% (74·6-80·9) of all attributable diarrhoea. With use of model-derived quantitative cutoffs to assess individual diarrhoeal cases, 2254 (42·5%) of 5304 cases had one diarrhoea-associated pathogen detected and 2063 (38·9%) had two or more, with Shigella spp and rotavirus being the pathogens most strongly associated with diarrhoea in children with mixed infections.

INTERPRETATION

A quantitative molecular diagnostic approach improved population-level and case-level characterisation of the causes of diarrhoea and indicated a high burden of disease associated with six pathogens, for which targeted treatment should be prioritised.

FUNDING

Bill & Melinda Gates Foundation.

Aeromonas-Associated Diarrhea in Children Under 5 Years: The GEMS Experience

We report the clinical findings, epidemiology, and risk factors for moderate-to-severe diarrhea (MSD) associated with Aeromonas species in children 0-59 months of age, from the Global Enteric Multicenter Study, conducted at three sites in south Asia and four sites in sub-Saharan Africa. Children with MSD were enrolled along with controls matched for age, gender, and neighborhood. Pooled, age-stratified conditional logistic regression models were applied to evaluate the association of Aeromonas infection controlling for coinfecting pathogens and sociodemographic variables. A pooled, age-stratified, multivariate logistic regression analysis was done to identify risk factors associated with Aeromonas positivity in MSD cases. A total of 12,110 cases and 17,291 matched controls were enrolled over a period of 48 months. Aeromonas was identified as a significant pathogen in 736 cases of MSD in Pakistan and Bangladesh (22.2%). Aeromonas remained a significant pathogen even after adjustment for the presence of other pathogens and sociodemographic factors. Odds ratio (OR) for Aeromonas were higher in the presence of Shigella (matched OR: 6.2, 95% confidence interval [CI]: 1.9-20.2). Cases of Aeromonas were likely to present with dysentery, particularly in the 0-11 months (OR: 1.4, 95% CI 1.0-2.0) and 12-23 months (OR: 1.8, 95% CI: 1.3-2.5) age group. The odds of Aeromonas increased with increasing degree of stunting, being highest for severe stunting (OR: 10.1, 95% CI: 3.6-28.9). Aeromonas is a significant pathogen for MSD in Pakistan and Bangladesh. Presence of dysentery and co-occurrence with other pathogens, notably Shigella spp. are significant features of Aeromonas-associated diarrhea.

Epidemiology, Seasonality and Factors Associated with Rotavirus Infection among Children with Moderate-to-Severe Diarrhea in Rural Western Kenya, 2008-2012: The Global Enteric Multicenter Study (GEMS)

Objective

To evaluate factors associated with rotavirus diarrhea and to describe severity of illness among children <5 years old with non-dysenteric, moderate-to-severe diarrhea (MSD) in rural western Kenya.

Methods

We analyzed data from children <5 years old with non-dysenteric MSD enrolled as cases in the Global Enteric Multicenter Study (GEMS) in Kenya. A non-dysenteric MSD case was defined as a child with ≥3 loose stools in 24 hrs. and one or more of the following: sunken eyes, skin tenting, intravenous rehydration, or hospitalization, who sought care at a sentinel health center within 7 days of illness onset. Rotavirus antigens in stool samples were detected by ELISA. Demographic and clinical information was collected at enrollment and during a single follow-up home visit at approximately 60 days. We analyzed diarrhea severity using a GEMS 17 point numerical scoring system adapted from the Vesikari score. We used logistic regression to evaluate factors associated with rotavirus infection.

Results

From January 31, 2008 to September 30, 2012, among 1,637 (92%) non-dysenteric MSD cases, rotavirus was detected in stools of 245 (15.0%). Rotavirus-positive compared with negative cases were: younger (median age, 8 vs. 13 months; p<0.0001), had more severe illness (median severity score, 9 vs 8; p<0.0001) and had to be hospitalized more frequently (37/245 [15.1%] vs. 134/1,392 [9.6%]), p <0.013). Independent factors associated with rotavirus infection included age 0–11 months old (aOR = 5.29, 95% CI 3.14–8.89) and presenting with vomiting ≥3 times/24hrs (aOR = 2.58, 95% CI [1.91–3.48]). Rotavirus was detected more commonly in warm and dry months than in the cool and rainy months (142/691 [20%] vs 70/673 [10%]) p<0.0001).

Conclusions

Diarrhea caused by rotavirus is associated with severe symptoms leading to hospitalization. Consistent with other settings, infants had the greatest burden of disease.

Characteristics of bacterial pathogens associated with acute diarrhea in children under 5 years of age: a hospital-based cross-sectional study

Background

Acute diarrhea is a leading cause of morbidity and mortality in children, particularly in those under the age of 5 years. Rotavirus is recognized as the leading cause of acute diarrhea in children, however, the contribution of bacterial pathogens as causative agents varies throughout the world. Here we report a hospital-based prospective study to analyze the characteristics of bacterial pathogens associated with acute diarrhea in children under 5 years of age.

Methods

Stool samples were collected from 508 patients with acute diarrhea under 5 years of age who presented at our hospital. Nine pathogens were isolated and identified by culturing, serology or PCR, these included Salmonella spp., Shigella spp., Vibrio cholerae, diarrheagenic Escherichia coli (DEC), Aeromonas spp., Plesiomonas spp., Vibrio parahaemolyticus, Campylobacter spp. and Yersinia enterocolitica. Antimicrobial sensitivity tests of these pathogens were conducted. The most commonly detected pathogen, Salmonella spp., was further investigated by PCR and sequencing of antibiotic resistance-related genes.

Results

Pathogens were identified in 20.1 % of the 508 samples. The most commonly detected pathogens were Salmonella spp. (8.5 %), followed by DEC (4.7 %), Campylobacter jejuni (3.0 %) and Aeromonas spp. (2.0 %). The resistance rates to ampicillin and tetracycline in Salmonella spp. were >60 %, but were <30 % to cephalosporins and quinolones. More than 50 % of DEC strains displayed resistance to ampicillin, cefotaxime and tetracycline, and 60 % of C. jejuni strains were resistant to ciprofloxacin but highly sensitive to the other antibiotics. Among 12 cephalosporin-resistant Salmonella isolates, TEM-1 and CTX-M-14 determinants were present in two (16.7 %) isolates. PCR screening for plasmid-mediated quinolone resistance genes revealed gyrA mutations in one of three highly quinolone resistant isolates.

Conclusions

Salmonella spp., DEC, Campylobacter spp. and Aeromonas spp. were the most commonly detected bacterial pathogens in children under the age of 5 years with acute diarrhea. Our findings indicate that ampicillin and tetracycline are not suitable as first line therapeutic drugs against Salmonella spp. Resistance to third generation cephalosporins and quinolones was also detected. TEM-1 and CTX-M-14 genetic determinants, and gyrA mutations, were the major mechanisms associated with high levels of cephalosporin and quinolone resistance, respectively, in Salmonella isolates.

First report of predation of Giardia sp. cysts by ciliated protozoa and confirmation of predation of Cryptosporidium spp. oocysts by ciliate species

Ciliated protozoa are important components of the microbial food web in various habitats, especially aquatic environments. These organisms are useful bioindicators for both environmental quality assessment and the wastewater purification process. The pathogenic parasitic protozoan species Giardia and Cryptosporidium represent a significant concern for human health, being responsible for numerous disease outbreaks worldwide. The predation of cysts and oocysts in 15 ciliate species from water and sewage samples collected in Campinas, São Paulo, Brazil were verified under laboratory conditions. The ciliated protozoan species were selected based on their mode of nutrition, and only bacterivorous and suspension-feeders were considered for the experiments. The species Blepharisma sinuosum, Euplotes aediculatus, Sterkiella cavicola, Oxytricha granulifera, Vorticella infusionum, Spirostomum minus, and Stentor coeruleus ingested cysts and oocysts, the resistance forms of Giardia spp. and Cryptosporidium spp., respectively. This is the first time that the ingestion of Giardia cysts by ciliated protozoa has been reported. These findings may contribute to a better understanding of the biological removal of these pathogens from aquatic environments.