Diarrhea in American infants and young children in the community setting: incidence, clinical presentation and microbiology

Molecular characterization of Clostridium perfringens isolates from a tertiary children's hospital in Guangzhou, China, establishing an association between bacterial colonization and food allergies in infants

BACKGROUND

Cow's milk protein allergy (CMPA) is one of the most common types of food allergy in infants. Faecal pathogen cultures showed that the positive rate of Clostridium perfringens was more than 30%, which was significantly higher than that for other bacteria. Therefore, it is speculated that Clostridium perfringens colonization may be one of the pathogenetic factors for CMPA in infants. We conducted a real-world evidence study. Infants aged 0-6 months with diarrhoea and mucoid and/or bloody stools were recruited from a large tertiary hospital in China. Faecal pathogen cultures for the detection of Clostridium perfringens were confirmed by flight mass spectrometry, and potential toxin genes were identified using PCR. After 12 months of follow-up, the diagnoses of CMPA and food allergy were recorded. The correlation was assessed by Pearson correlation analysis.

RESULTS

In this study, 358 infants aged 0-6 months with gastrointestinal symptoms and faecal pathogen cultures were recruited. A total of 270 (44.07% girls; mean age, 2.78 ± 2.84 months) infants were followed up for 12 months. Overall, the rate of positivity for Clostridium perfringens in faecal pathogen cultures was 35.75% (128/358) in infants aged ≤ 6 months. The earliest Clostridium perfringens colonization was detected within 2 days after birth. The majority of Clostridium perfringens isolates were classified as type C in 85 stool samples. In the Clostridium perfringens-positive group, 48.21% (54/112) of infants were clinically diagnosed with food allergies after 12 months, including 37.5% (42/112) with CMPA, which was significantly higher than that of the negative group, with 7.59% (12/158) exhibiting food allergies and 5.06% (8/158) presenting CMPA (P < 0.0001). Faecal Clostridium perfringens positivity was significantly correlated with CMPA, food allergy, faecal occult blood, faecal white blood cells, antibiotic use, increased peripheral blood platelet counts, and decreased haemoglobin levels (P < 0.0001).

CONCLUSIONS

This study demonstrates that intestinal colonization by Clostridium perfringens is common in infants. The majority of Clostridium perfringens isolates are classified as type C. Colonization of the intestine by Clostridium perfringens is associated with the development of CMPA and food allergy in infants.

Worldwide prevalence and genotype distribution of human astrovirus in gastroenteritis patients: A systematic review and meta-analysis

AIM

Human astrovirus (HAstV) is an important causative agent of gastroenteritis in humans, which mainly infects young children and the elderly. The goal of this study was to conduct a meta-analytic review of the prevalence of HAstV amongst patients with gastroenteritis, and to shed light on the connection between HAstV infection and gastroenteritis.

METHODS

Systematic literature searches were conducted to identify all potentially relevant studies recorded up to April 8th, 2022. For study weighting, the inverse variance method was employed and the random-effects model was applied to evaluate data. For case-control studies, the pooled odds ratio (OR) and 95% confidence interval (CI) were calculated to establish the relationship between HAstV infection and gastroenteritis.

RESULTS

Among 302423 gastroenteritis patients from 69 different countries, the overall pooled prevalence of HAstV infection was 3.48% (95% CI: 3.11%-3.89%). Case-control approach was used in 39 investigations, and the overall prevalence of HAstV infection among the 11342 healthy controls was 2.01% (95% CI: 1.40%-2.89%). Gastroenteritis and HAstV infection were associated with a pooled OR of 2.16 (95% CI: 1.72-2.71; P < 0.0001; I² = 33.7%). The most commonly found HAstV genotypes in gastroenteritis patients were HAstV1 (62.18%), HAstV7 (33.33%), and HAstV-MLB1 (17.43%).

CONCLUSION

The frequency of HAstV infection was the highest in children under the age of five, and in developing countries. The prevalence rate of HAstV was not influenced by gender. Semi-nested and nested RT-PCR were highly sensitive assays for detecting HAstV infections.

Clinical Metagenomics Is Increasingly Accurate and Affordable to Detect Enteric Bacterial Pathogens in Stool

Stool culture is the gold standard method to diagnose enteric bacterial infections; however, many clinical laboratories are transitioning to syndromic multiplex PCR panels. PCR is rapid, accurate, and affordable, yet does not yield subtyping information critical for foodborne disease surveillance. A metagenomics-based stool testing approach could simultaneously provide diagnostic and public health information. Here, we evaluated shotgun metagenomics to assess the detection of common enteric bacterial pathogens in stool. We sequenced 304 stool specimens from 285 patients alongside routine diagnostic testing for Salmonella spp., Campylobacter spp., Shigella spp., and shiga-toxin producing Escherichia coli. Five analytical approaches were assessed for pathogen detection: microbiome profiling, Kraken2, MetaPhlAn, SRST2, and KAT-SECT. Among analysis tools and databases compared, KAT-SECT analysis provided the best sensitivity and specificity for all pathogens tested compared to culture (91.2% and 96.2%, respectively). Where metagenomics detected a pathogen in culture-negative specimens, standard PCR was positive 85% of the time. The cost of metagenomics is approaching the current combined cost of PCR, reflex culture, and whole genome sequencing for pathogen detection and subtyping. As cost, speed, and analytics for single-approach metagenomics improve, it may be more routinely applied in clinical and public health laboratories.

Global Prevalence of Yersinia enterocolitica in Cases of Gastroenteritis: A Systematic Review and Meta-Analysis

The prevalence of Yersinia enterocolitica in gastroenteritis is often underestimated. It relates considerably to morbidity and medical expenses around the world. Understanding the cause of gastroenteritis leads to making the appropriate treatment decisions. We systematically searched PubMed, Science Direct, Embase, and Scopus to identify all published studies between Jan. 1, 2000, and Dec. 31, 2019, to assess the prevalence of Y. enterocolitica in gastroenteritis patients. A total of 5039 articles were identified that lead to the extraction of data from 47 of them. The pooled prevalence of Y. enterocolitica in cases of gastroenteritis was estimated as 1.97% (1.32–2.74%) in the culture method and 2.41% (1.07–4.22%) in the molecular method. Among the biotypes of Y. enterocolitica, 1A (62.48%) and 1B (2.14%) had the most and least prevalence, respectively. Serotype O3 Y. enterocolitica with 39.46% had the highest and O5,27 with 0.0% had the least prevalence in gastroenteritis cases. In conclusion, the findings of this systematic review show that Y. enterocolitica is prevalent in gastroenteritis in all age groups. Serotypes O3 and O9 of Y. enterocolitica had the highest prevalence and O5,27 had the least prevalence in diarrheal patients. The prevalence of Y. enterocolitica was similar in both gender and different seasons. It should be noted that to determine the role of the organism, more studies are needed especially in food-borne diseases.

Comparative Genomics of Atypical Enteropathogenic Escherichia coli from Kittens and Children Identifies Bacterial Factors Associated with Virulence in Kittens

Typical enteropathogenic Escherichia coli (tEPEC) is a leading cause of diarrhea and associated death in children worldwide. Atypical EPEC (aEPEC) lacks the plasmid encoding bundle-forming pili and is considered less virulent, but the molecular mechanism of virulence is poorly understood. We recently identified kittens as a host for aEPEC where intestinal epithelial colonization was associated with diarrheal disease and death. The purposes of this study were to (i) determine the genomic similarity between kitten aEPEC and human aEPEC isolates and (ii) identify genotypic or phenotypic traits associated with virulence in kitten aEPEC. We observed no differences between kitten and human aEPEC in core genome content or gene cluster sequence identities, and no distinguishing genomic content was observed between aEPEC isolates from kittens with nonclinical colonization (NC) versus those with lethal infection (LI). Variation in adherence patterns and ability to aggregate actin in cultured cells mirrored descriptions of human aEPEC. The aEPEC isolated from kittens with LI were significantly more motile than isolates from kittens with NC. Kittens may serve as a reservoir for aEPEC that is indistinguishable from human aEPEC isolates and may provide a needed comparative animal model for the study of aEPEC pathogenesis. Motility seems to be an important factor in pathogenesis of LI associated with aEPEC in kittens.

Diagnostic Accuracy of Nucleic Acid Amplification-Based Assays for Clostridium perfringens-Associated Diseases: a Systematic Review and Meta-analysis

Timely and accurate methods for detecting Clostridium perfringens-associated diseases (CPAD) are crucial to improve patient care. A number of studies have evaluated the accuracy of nucleic acid amplification tests (NAAT) in detecting CPAD, but decisive results about their effectiveness have not been reported. We conducted a meta-analysis to evaluate the diagnostic performance of NAAT for detecting C. perfringens in clinical diarrheal samples. Five databases including PubMed, Embase, Scopus, Web of Science, and the Cochrane library were systematically probed for studies published before 6 December 2019. From 2,632 citations, we identified five eligible studies comprising 817 samples. Three studies (n = 695 samples) compared NAAT with a microbiological culture while the other three studies (n = 322 samples) compared NAAT with an immunoassay. NAAT revealed higher diagnostic accuracy against immunoassay (sensitivity, 0.53 [95% confidence interval [CI], 0.35 to 0.7]; specificity, 0.97 [95% CI, 0.95 to 0.99]; positive likelihood ratio [PLR], 23.2 [95% CI, 3.49 to 153.98]; negative likelihood ratio [NLR], 0.25 [95% CI, 0 to 245.28]; diagnostic odds ratio [DOR], 74.11 [95% CI, 2.11 to 2,593.7]) than microbiological culture (sensitivity, 0.31 [95% CI, 0.22 to 0.41]; specificity, 0.95 [95% CI, 0.93 to 0.97]; PLR, 11.56 [95% CI, 3.87 to 34.6]; NLR, 0.57 [95% CI, 0.27 to 1.21]; DOR, 18.1 [95% CI, 4.83 to 67.8]). NAAT pooled specificity was consistently ≥95% against that of applied reference standards. A meta-regression and subgroup analysis of sample condition, gene target, study design, and reference standards could not explain the heterogeneity (P > 0.05) in the diagnostic efficiency. The analysis has demonstrated that the diagnostic accuracy of NAAT is relatively insufficient to replace traditional reference standards as a single diagnostic test. NAAT can be applied in combination with microbiological culture because of the advantage of time to result and in scenarios where traditional tests are not feasible. Further investigations in this direction with larger sample sizes are still warranted to support our findings.

Whole genome sequencing and metagenomics for outbreak investigation, source attribution and risk assessment of food-borne microorganisms

This Opinion considers the application of whole genome sequencing (WGS) and metagenomics for outbreak investigation, source attribution and risk assessment of food‐borne pathogens. WGS offers the highest level of bacterial strain discrimination for food‐borne outbreak investigation and source‐attribution as well as potential for more precise hazard identification, thereby facilitating more targeted risk assessment and risk management. WGS improves linking of sporadic cases associated with different food products and geographical regions to a point source outbreak and can facilitate epidemiological investigations, allowing also the use of previously sequenced genomes. Source attribution may be favoured by improved identification of transmission pathways, through the integration of spatial‐temporal factors and the detection of multidirectional transmission and pathogen–host interactions. Metagenomics has potential, especially in relation to the detection and characterisation of non‐culturable, difficult‐to‐culture or slow‐growing microorganisms, for tracking of hazard‐related genetic determinants and the dynamic evaluation of the composition and functionality of complex microbial communities. A SWOT analysis is provided on the use of WGS and metagenomics for Salmonella and Shigatoxin‐producing Escherichia coli (STEC) serotyping and the identification of antimicrobial resistance determinants in bacteria. Close agreement between phenotypic and WGS‐based genotyping data has been observed. WGS provides additional information on the nature and localisation of antimicrobial resistance determinants and on their dissemination potential by horizontal gene transfer, as well as on genes relating to virulence and biological fitness. Interoperable data will play a major role in the future use of WGS and metagenomic data. Capacity building based on harmonised, quality controlled operational systems within European laboratories and worldwide is essential for the investigation of cross‐border outbreaks and for the development of international standardised risk assessments of food‐borne microorganisms.

Giardia: an under-reported foodborne parasite

Foodborne zoonotic pathogens are a serious public health issue and result in significant global economic losses. Despite their importance to public health, epidemiological data on foodborne diseases including giardiasis caused by the enteric parasite, Giardia duodenalis, are lacking. This parasite is estimated to cause ∼28.2 million cases of diarrhoea each year due to contamination of food, but very few foodborne outbreaks have been documented due to the limitations of current detection as well as surveillance methods. The current method for the recovery of Giardia cysts from food matrices using immunomagnetic separation requires further standardisation and cost reduction before it can be widely used. It also should incorporate downstream molecular procedures for genotyping, and traceback and viability analyses. Foodborne giardiasis can be potentially controlled through improvements in national disease surveillance systems and the establishment of Hazard Analysis and Critical Control Point interventions across the food chain. Studies are needed to assess the true prevalence and public health impact of foodborne giardiasis.

Detection of Uncommon Enteric Bacterial Pathogens from Acute Diarrheal Specimens Using SYBR-Green Real Time PCR

Acute diarrheal disease is a major health problem, and the second most common cause of death in children under 5 years of age. Conventional diagnostic methods are laborious, time consuming, and occasionally inaccurate. We used SYBR-Green real-time PCR for the detection of 10 uncommon bacterial pathogens using fecal specimens from acute diarrheal patients. In the SYBR-Green real-time PCR assay, the products formed were identified based on a melting point temperature curve analysis, and the assay was validated with the respective reference strain. In a retrospective study, we tested 1,184 stool specimens previously examined using conventional culture methods. Enterotoxigenic Bacteriodes fragilis was detected in 6.7% of the samples followed by enterotoxigenic Bacillus cereus (5.1%), Clostridium perfringens (3.9%), and Aeromonas hydrophila (3.8%). In the prospective study, A. hydrophila, Staphylococcus aureus, and C. perfringens were predominantly detected in 11 > 5 years of age, using real-time PCR. The real-time PCR assay is comprehensive, rapid, accurate, and well suited for surveillance or diagnostic purposes to detect uncommon bacterial pathogens, and should be useful in initiating appropriate care and thereby reducing patient risk.

Serum procalcitonin levels can be used to differentiate between inflammatory and non-inflammatory diarrhea in acute infectious diarrhea

In this study, we assess the possibility of using procalcitonin levels to differentiate between inflammatory diarrhea and non-inflammatory diarrhea in acute infectious diarrhea.We reviewed the records of 1176 patients who had symptoms of diarrhea, fever (≥37.8 °C), and abdominal pain between March 2011 and May 2015. After applying exclusion criteria, a sample of 514 patients was considered for study. The patient sample was divided into Group A and Group B for inflammatory diarrhea and non-inflammatory diarrhea, respectively. The assessment involved comparing the laboratory characteristics with the clinical characteristics of the groups.The characteristics of Group A, such as white blood cell (WBC), C-reactive protein (CRP), absolute neutrophil count (ANC), and procalcitonin levels, were relatively higher than those of Group B (P < .001 for Group A). A receiver operator characteristic (ROC) analysis revealed that the highest area-under-the-curve (AUC) value of procalcitonin (0.797; 95% confidence interval [CI] [0.760, 0.831]; P < .001), could be used to differentiate between the 2 groups. Procalcitonin exhibited a sensitivity and a specificity of 87.03% and 68.75%, respectively, at a 0.08 ng/mL cut-off level.Procalcitonin was a good candidate biomarker of inflammatory diarrhea than other inflammatory markers.

Urbanization and the gut microbiota in health and inflammatory bowel disease

In the 21st century, urbanization represents a major demographic shift in developed and developing countries. Rapid urbanization in the developing world has been associated with an increasing incidence of several autoimmune diseases, including IBD. Patients with IBD exhibit a decrease in the diversity and richness of the gut microbiota, while urbanization attenuates the gut microbial diversity and might have a role in the pathogenesis of IBD. Environmental exposures during urbanization, including Westernization of diet, increased antibiotic use, pollution, improved hygiene status and early-life microbial exposure, have been shown to affect the gut microbiota. The disparate patterns of the gut microbiota composition in rural and urban areas offer an opportunity to understand the contribution of a 'rural microbiome' in potentially protecting against the development of IBD. This Perspective discusses the effect of urbanization and its surrogates on the gut microbiome (bacteriome, virome, mycobiome and helminths) in both human health and IBD and how such changes might be associated with the development of IBD.

Surveillance of Foodborne Pathogens: Towards Diagnostic Metagenomics of Fecal Samples

Diagnostic metagenomics is a rapidly evolving laboratory tool for culture-independent tracing of foodborne pathogens. The method has the potential to become a generic platform for detection of most pathogens and many sample types. Today, however, it is still at an early and experimental stage. Studies show that metagenomic methods, from sample storage and DNA extraction to library preparation and shotgun sequencing, have a great influence on data output. To construct protocols that extract the complete metagenome but with minimal bias is an ongoing challenge. Many different software strategies for data analysis are being developed, and several studies applying diagnostic metagenomics to human clinical samples have been published, detecting, and sometimes, typing bacterial infections. It is possible to obtain a draft genome of the pathogen and to develop methods that can theoretically be applied in real-time. Finally, diagnostic metagenomics can theoretically be better geared than conventional methods to detect co-infections. The present review focuses on the current state of test development, as well as practical implementation of diagnostic metagenomics to trace foodborne bacterial infections in fecal samples from animals and humans.

Recent Issues in Pediatric Clostridium difficile Infection

PURPOSE OF REVIEW

We focus on two recent aspects of Clostridium difficile infection (CDI) in children, namely the emergence of community-associated CDI (CA-CDI) and the incidence and prevention of recurrent CDI.

RECENT FINDINGS

Current surveys suggest that a large proportion of all pediatric CDI is acquired in the community. Risk factors and frequency estimates of pediatric CA-CDI, however, are confounded in babies and toddlers by a high rate of asymptomatic excretion, whose detection likely is exaggerated by the wide use of highly sensitive nucleic acid amplification tests. Recurrent diarrhea occurs in up to 25% of children with CDI. Preventative strategies for recurrent CDI in adults, namely pulse and taper antibiotic dosing, use of anti-CDI drugs with mild effect on the colonic microbiome, fecal microbiota transplantation, and passive immune therapy, currently are being tested in children. Future studies are required to better characterize community acquisition of CDI in children and to define the safety and effectiveness of preventative strategies for recurrent CDI.

Association of Atypical Enteropathogenic Escherichia coli with Diarrhea and Related Mortality in Kittens

Diarrhea is responsible for the death of approximately 900,000 children per year worldwide. In children, typical enteropathogenic Escherichia coli (EPEC) is a common cause of diarrhea and is associated with a higher hazard of death. Typical EPEC infection is rare in animals and poorly reproduced in experimental animal models. In contrast, atypical EPEC (aEPEC) infection is common in both children and animals, but its role in diarrhea is uncertain. Mortality in kittens is often attributed to diarrhea, and we previously identified enteroadherent EPEC in the intestines of deceased kittens. The purpose of this study was to determine the prevalence and type of EPEC in kittens and whether infection was associated with diarrhea, diarrhea-related mortality, gastrointestinal pathology, or other risk factors. Kittens with and without diarrhea were obtained from two shelter facilities and determined to shed atypical EPEC at a culture-based prevalence of 18%. In contrast, quantitative PCR detected the presence of the gene for intimin (eae) in feces from 42% of kittens. aEPEC was isolated from kittens with and without diarrhea. However, kittens with diarrhea harbored significantly larger quantities of aEPEC than kittens without diarrhea. Kittens with aEPEC had a significantly greater severity of small intestinal and colonic lesions and were significantly more likely to have required subcutaneous fluid administration. These findings identify aEPEC to be prevalent in kittens and a significant primary or contributing cause of intestinal inflammation, diarrhea, dehydration, and associated mortality in kittens.

Genetic Virulence Profile of Enteroaggregative Escherichia coli Strains Isolated from Danish Children with Either Acute or Persistent Diarrhea

Enteroaggregative Escherichia coli (EAEC) is frequently found in diarrheal stools worldwide. It has been associated with persistent diarrhea, weight loss, and failure to thrive in children living in developing countries. A number of important EAEC virulence genes are identified; however, their roles in acute and persistent diarrhea have not been previously investigated. The aim of this study was to identify specific EAEC virulence genes associated with duration and type of diarrhea in Danish children. We aimed to improve the current diagnostics of EAEC and enable targeting of strains with an expected severe disease course. Questionnaires answered by parents provided information regarding duration of diarrhea and presence of blood or mucus. A total of 295 EAEC strains were collected from children with acute (≤7 days) and persistent diarrhea (≥14 days) and were compared by using multiplex PCR targeting the genes sat, sepA, pic, sigA, pet, astA, aatA, aggR, aaiC, aap, agg3/4C, ORF3, aafA, aggA, agg3A, agg4A, and agg5A. Furthermore, the distribution of EAEC genes in strains collected from cases of bloody, mucoid, and watery diarrhea was investigated. The classification and regression tree analysis (CART) was applied to investigate the relationship between EAEC virulence genes and diarrheal duration and type. Persistent diarrhea was associated with strains lacking the pic gene (p = 0.002) and with the combination of the genes pic, sat, and absence of the aggA gene (p = 0.05). Prolonged diarrhea was associated with the combination of the genes aatA and astA (p = 0.03). Non-mucoid diarrhea was associated with strains lacking the aatA gene (p = 0.004). Acute diarrhea was associated with the genes aggR, aap, and aggA by individual odds ratios. Resistance toward gentamicin and ciprofloxacin was observed in 7.5 and 3% of strains, respectively. Multi-drug resistance was observed in 38% of strains. Genetic host factors have been associated with an increased risk of EAEC-associated disease. Therefore, we investigated a panel of risk factors in two groups of children—EAEC-positive and EAEC-negative—to identify additional factors predisposing to disease. The duration of breastfeeding was positively correlated with the likelihood of belonging to the EAEC-negative group of children.

Evaluating next-generation sequencing for direct clinical diagnostics in diarrhoeal disease

The accurate microbiological diagnosis of diarrhoea involves numerous laboratory tests and, often, the pathogen is not identified in time to guide clinical management. With next-generation sequencing (NGS) becoming cheaper, it has huge potential in routine diagnostics. The aim of this study was to evaluate the potential of NGS-based diagnostics through direct sequencing of faecal samples. Fifty-eight clinical faecal samples were obtained from patients with diarrhoea as part of the routine diagnostics at Hvidovre University Hospital, Denmark. Ten samples from healthy individuals were also included. DNA was extracted from faecal samples and sequenced on the Illumina MiSeq system. Species distribution was determined with MGmapper and NGS-based diagnostic prediction was performed based on the relative abundance of pathogenic bacteria and Giardia and detection of pathogen-specific virulence genes. NGS-based diagnostic results were compared to conventional findings for 55 of the diarrhoeal samples; 38 conventionally positive for bacterial pathogens, two positive for Giardia, four positive for virus and 11 conventionally negative. The NGS-based approach enabled detection of the same bacterial pathogens as the classical approach in 34 of the 38 conventionally positive bacterial samples and predicted the responsible pathogens in five of the 11 conventionally negative samples. Overall, the NGS-based approach enabled pathogen detection comparable to conventional diagnostics and the approach has potential to be extended for the detection of all pathogens. At present, however, this approach is too expensive and time-consuming for routine diagnostics.

Disparities in Breastfeeding: Impact on Maternal and Child Health Outcomes and Costs

OBJECTIVE

To estimate the disease burden and associated costs attributable to suboptimal breastfeeding rates among non-Hispanic blacks (NHBs), Hispanics, and non-Hispanic whites (NHWs).

STUDY DESIGN

Using current literature on associations between breastfeeding and health outcomes for 8 pediatric and 5 maternal diseases, we used Monte Carlo simulations to evaluate 2 hypothetical cohorts of US women followed from age 15 to 70 years and their infants followed from birth to age 20 years. Accounting for differences in parity, maternal age, and birth weights by race/ethnicity, we examined disease outcomes and costs using 2012 breastfeeding rates by race/ethnicity and outcomes that would be expected if 90% of infants were breastfed according to recommendations for exclusive and continued breastfeeding duration.

RESULTS

Suboptimal breastfeeding is associated with a greater burden of disease among NHB and Hispanic populations. Compared with a NHW population, a NHB population had 1.7 times the number of excess cases of acute otitis media attributable to suboptimal breastfeeding (95% CI 1.7-1.7), 3.3 times the number of excess cases of necrotizing enterocolitis (95% CI 2.9-3.7), and 2.2 times the number of excess child deaths (95% CI 1.6-2.8). Compared with a NHW population, a Hispanic population had 1.4 times the number of excess cases of gastrointestinal infection (95% CI 1.4-1.4) and 1.5 times the number of excess child deaths (95% CI 1.2-1.9).

CONCLUSIONS

Racial/ethnic disparities in breastfeeding have important social, economic, and health implications, assuming a causal relationship between breastfeeding and health outcomes.

xMAP Technology: Applications in Detection of Pathogens

xMAP technology is applicable for high-throughput, multiplex and simultaneous detection of different analytes within a single complex sample. xMAP multiplex assays are currently available in various nucleic acid and immunoassay formats, enabling simultaneous detection and typing of pathogenic viruses, bacteria, parasites and fungi and also antigen or antibody interception. As an open architecture platform, the xMAP technology is beneficial to end users and therefore it is used in various pharmaceutical, clinical and research laboratories. The main aim of this review is to summarize the latest findings and applications in the field of pathogen detection using microsphere-based multiplex assays.

Linking the Microbiota, Chronic Disease, and the Immune System

Chronic inflammatory diseases (CIDs) are the most important causes of mortality in the world today and are on the rise. We now know that immune-driven inflammation is critical in the etiology of these diseases, though the environmental triggers and cellular mechanisms that lead to their development are still mysterious. Many CIDs are associated with significant shifts in the microbiota toward inflammatory configurations, which can affect the host both by inducing local and systemic inflammation and by alterations in microbiota-derived metabolites. This review discusses recent findings suggesting that shifts in the microbiota may contribute to chronic disease via effects on the immune system.

Tropheryma whipplei associated with diarrhoea in young children

Tropheryma whipplei was detected in preliminary studies in faeces of young children with diarrhoea and also in faeces of asymptomatic persons, not only in Europe but also in Africa. In this study, the link between this bacterium and the presence of acute diarrhoea was evaluated in a large group of children. From December 2009 to January 2013, rectal swabs collected from 3796 children in the emergency departments of university hospitals in Marseille, France, were analysed: 555 children (245 female and 310 male, from 6 days to 6 years old) with acute diarrhoea defined as at least three loose stools per day for <1 week and 3241 children (1444 female and 1797 male, from 22 days to 6 years old) without diarrhoea. Specific quantitative real-time PCR was performed to detect the presence of T. whipplei and of two enteric pathogens Clostridium difficile and Giardia duodenalis. Tropheryma whipplei was significantly more common in children with diarrhoea (22/555, 4%) than without (56/3241, 1.7%; p 0.001). Neither C. difficile nor G. duodenalis showed this association. For C. difficile, 39 of 531 (7.3%) children with diarrhoea were positive versus 184 of 3119 (5.9%) of children without diarrhoea (p 0.25). For G. duodenalis, 2 of 529 (0.37%) children with diarrhoea were positive versus 5 of 3119 (0.16%) children without diarrhoea (p 0.26). Tropheryma whipplei was found more commonly in autumn. Tropheryma whipplei is significantly associated with diarrhoea in children, suggesting that the bacterium may be a cause of acute diarrhoea.

Hospital acquired Clostridium difficile infection in pediatric wards: a retrospective case-control study

Background

Clostridium difficile is a major cause of antibiotic-associated diarrhea and frequently results in healthcare-associated infections. The aim of this study was to determine the incidence and potential risk factors for C. difficile infection (CDI) in hospitalized children who developed diarrhea. A retrospective study was performed at a university hospital in İstanbul over a three-year period (2012–2014).

Results

During the study period 12,196 children were hospitalized, among them 986 (8 %) children with diarrhea were investigated for CDI and 100 (0.8 %) children were diagnosed with CDI. The incidence of CDI in hospitalized children was 4/1000, 9/1000 and 9/1000 patients per year in year 2012, 2013 and 2014, respectively (p = 0.008, p < 0.01). The mean age of children with CDI (2.6 ± 2.6 months) was lower than children without CDI (57.5 ± 63.5 months) [p = 0.001]. In the multivariate analysis, the presence of underlying chronic diseases [presence of malnutrition (OR 7, 95 % CI 1.33–36.7, p = 0.021), presence of solid organ tumors (OR 6, 95 % CI 2.4–15.7, p < 0.00), presence of congenital heart diseases (OR 4.6, 95 % CI 1.13–18.7, p = 0.03), hospitalization in PICU (OR 15.6, 95 % CI 3.2–75.8, p = 0.001) and hospitalization in hematology and oncology ward (OR 7.8, 95 % CI 2–29.9, p = 0.002)] were found to be independent risk factors for CDI.

Conclusion

This is the first description of the incidence and associated risk factors of CDI in Turkish children. One of the most important risk factor was prior antibiotic exposure which emphasizes the importance of antibiotic stewardship programs.

The role of Clostridium difficile in the paediatric and neonatal gut - a narrative review

Clostridium difficile is an important nosocomial pathogen in adults. Its significance in children is less well defined, but cases of C. difficile infection (CDI) appear to be increasingly prevalent in paediatric patients. This review aims to summarize reported Clostridium difficile carriage rates across children of different age groups, appraise the relationship between CDI and factors such as method of delivery, type of infant feed, antibiotic use, and co-morbidities, and review factors affecting the gut microbiome in children and the host immune response to C. difficile. Searches of PubMed and Google Scholar using the terms 'Clostridium difficile neonates' and 'Clostridium difficile children' were completed, and reference lists of retrieved publications screened for further papers. In total, 88 papers containing relevant data were included. There was large inter-study variation in reported C. difficile carriage rates. There was an association between CDI and recent antibiotic use, and co-morbidities such as immunosuppression and inflammatory bowel disease. C. difficile was also found in stools of children with diarrhoea attributed to other pathogens (e.g. rotavirus). The role of C. difficile in the paediatric gut remains unclear; is it an innocent bystander in diarrhoeal disease caused by other organisms, or a pathogen causing subclinical to severe symptoms? Further investigation of the development of serological and local host response to C. difficile carriage may shed new light on disease mechanisms. Work is underway on defining a framework for diagnosis and management of paediatric CDI.

The trend of enteropathogenic Escherichia coli towards atypical multidrug resistant genotypes

The aim of this study was to investigate the prevalence of multidrug resistance (MDR) in atypical enteropathogenic Escherichia coli (EPEC) genotypes among 547 diarrheal children. All E. coli isolates with eae⁺stx1^-stx2^- genotypes included in this study and atypical property of EPEC was characterized by the absence of Bundle-forming pili (bfpA gene). Bacterial pathogens were detected in 70 patients (12.8%) among which atypical EPEC (5.3%) were the most common. The higher resistance rate was seen to tetracycline (70%), cotrimoxazole (60%) and nalidixic acid (53.3%) related to MDR phenotype in 63.3% of isolates. The presence of class 1 and 2 integrons was 30% and 6.6% with the dominance of dfrA, aadA gene cassettes among the isolates. Eleven out of 21 phenotypically tetracycline-resistant isolates (52.38%) harboured one or two tetracycline resistance genes (A-D) which shows the incapability of known data to reasonable tetracycline resistance phenotypes among EPEC isolates. A high level of genotypic diversity was seen among the isolates by Pulsed-field gel electrophoresis method which ranged from 89.7 to 29% and no clear correlation was obtained between tetracycline resistance or integron carriage and specific pulsotypes. In conclusion, the data presented here add to knowledge about the heterogeneous nature of MDR EPEC population in Iran which has a growing tendency towards atypical genotypes. The distribution of integrons among EPEC isolates in Iran is decreasing; although, the resistance gene content is almost stable through years.

Pathotypic and Phylogenetic Study of Diarrheagenic Escherichia coli and Uropathogenic E. coli Using Multiplex Polymerase Chain Reaction

BACKGROUND

Acute diarrheal disease and urinary tract infection are leading causes of childhood morbidity and mortality in the developing world. Diarrheagenic Escherichia coli (DEC) has been identified as a major etiologic agent of diarrhea worldwide, and urinary tract infection (UTI) caused by uropathogenic Escherichia coli (UPEC) is one of the most common bacterial infections among human beings. Quick and precise detection of these bacteria help provide more effective intervention and management of infection.

OBJECTIVES

In this study we present a precise and sensitive typing and phylogenetic study of UPEC and DEC using multiplex PCR in order to simplify and improve the intervention and management of diarrheal and UT infections.

MATERIALS AND METHODS

In total, 100 urinary tract infection samples (UTI) and 200 specimens from children with diarrhea, which had been diagnosed with E. coli as the underlying agent by differential diagnosis using MacConkey's agar and biochemical study, were submitted for molecular detection. Pathotyping of E. coli pathotypes causing urinary tract infection and diarrhea were examined using a two set multiplex PCR, targeting six specific genes. Phylogenetic typing was done by targeting three genes, including ChuA, YjaA and TspE4C2.

RESULTS

Overall, 88% of DEC and 54% of UTI isolates were positive for one or more of the six genes encoding virulence factors. Prevalence of the genes encoding virulence factors for DEC were 62%, 25%, 24%, 13%, 7% and 5% for ST (ETEC), LT (ETEC), aggR (EAggEC), daaD (DAEC), invE (EIEC) and eae (EPEC), respectively; whereas, the prevalence rates for the UTI samples were 23%, 14%, 6%, 6% and 4% for aggR (EAggEC), LT (ETEC), daaD (DAEC), invE (EIEC) and ST (ETEC), respectively. No coding virulence factors were detected for eae (EPEC). Group B2 was the most prevalent phylogroup and ST was the most frequently detected pathotype in all phylogroups.

CONCLUSIONS

ETEC and EAggEC were the most detected E. coli among stool and UTI samples, emphasizing the need to dedicate more health care attention to this group. In addition, our phylogenetic study may be helpful in figuring out the infection origin and for epidemiological studies. Nonetheless, more research studies with larger sample sizes are suggested for confirming our results.

Microbiota-Dependent Sequelae of Acute Infection Compromise Tissue-Specific Immunity

Infections have been proposed as initiating factors for inflammatory disorders; however, identifying associations between defined infectious agents and the initiation of chronic disease has remained elusive. Here, we report that a single acute infection can have dramatic and long-term consequences for tissue-specific immunity. Following clearance of Yersinia pseudotuberculosis, sustained inflammation and associated lymphatic leakage in the mesenteric adipose tissue deviates migratory dendritic cells to the adipose compartment, thereby preventing their accumulation in the mesenteric lymph node. As a consequence, canonical mucosal immune functions, including tolerance and protective immunity, are persistently compromised. Post-resolution of infection, signals derived from the microbiota maintain inflammatory mesentery remodeling and consequently, transient ablation of the microbiota restores mucosal immunity. Our results indicate that persistent disruption of communication between tissues and the immune system following clearance of an acute infection represents an inflection point beyond which tissue homeostasis and immunity is compromised for the long-term. VIDEO ABSTRACT.

Molecular Epidemiology of Enteric Adenovirus Gastroenteritis in under-Five-Year-Old Children in Iran

Background. Acute gastroenteritis is one of the major sources of morbidity and mortality among young children in developed and developing countries. The aim of this study was to determine the prevalence of human adenovirus- (HAdV-) 40 and HAdV-41 in children hospitalized with gastroenteritis in five different health centers of Iran. Methods. In a cross-sectional epidemiological study, we studied 2682 fecal specimens that were collected from children under the age of 5 years in five educational and therapeutic pediatric centers in Iran from February 2012 to February 2013. Samples were tested for HAdV-40 and HAdV-41, using a specific pair of primers in polymerase chain reaction (PCR) method. Results. HAdV-40 and HAdV-41 were detected in 132 (5.18%) of the patients with diarrhea. A significantly higher prevalence of HAdV-40 and HAdV-41 (58.3%) was observed in children under 12 months of age, compared to other age groups. The male to female ratio was 1.7. Conclusion. The results of this study demonstrated that HAdV-40 and HAdV-41 could be considered etiological agents for acute gastroenteritis among children in Iran. The PCR as a rapid test may increase the chance for a relatively mild course of the disease followed by a complete recovery and avoiding administration of unnecessary antibiotics.

Pitfalls in Diagnosis of Pediatric Clostridium difficile Infection

The incidence of Clostridium difficile infection (CDI) has risen among children and C difficile is increasingly recognized as an important cause of healthcare-associated diarrhea among pediatric patients. Still, increased identification of CDI in healthy children in the community and increased testing among infants requires cautious interpretation, given the high prevalence of asymptomatic colonization in young infants and frequent detection of viruses and other co-pathogens in stool specimens in these age groups. The significance of CDI among infants and the implications of positive C difficile testing among healthy children in the community are areas in need of further study.

Co-infection as a confounder for the role of Clostridium difficile infection in children with diarrhoea: a summary of the literature

Although Clostridium difficile is a major cause of antibiotic-associated diarrhoea in adults, the incidence and severity of C. difficile infection (CDI) in children is unclear. One complicating factor in assessing the role of CDI in children is the possibility of co-infection with other gastrointestinal pathogens. In this review, we summarise the literature concerning C. difficile co-infections in young children, in an attempt to discuss the rate of co-infections and their potential role in the severity of CDI clinical presentation. We identified 31 studies where co-infections were analysed, comprising 1,718 patients with positive C. difficile tests. The pooled percentage of reported co-infections was 20.7% (range 0-100%). Viral co-infections were most commonly reported (46%), with bacteria and parasites accounting for 14.9% and 0.01% of cases, respectively. However, the panel of co-infections tested for varied considerably among studies and 38% of stated co-infections did not have a pathogen reported. Substantial variation in how and when tests for gastrointestinal co-infections are carried out, small sample sizes and a lack of clear CDI case definitions preclude meaningful conclusions on the true rate of co-infections in this patient population. This review suggests that co-infections may be common in children with diarrhoea who tested positive for C. difficile. Given a lack of CDI case definitions, especially in young children under the age of 5 years, a broad panel of pathogens should be tested for to exclude other microbiological causes. However, the summarised poor quality of the available literature on this subject highlights a need for further studies.

The burden of different pathogens in acute diarrhoeal episodes among a cohort of Egyptian children less than five years old

Introduction

Diarrhoea continues to cause significant morbidity in Egypt.

Aim

To determine the frequency and distribution of different enteropathogens in acute diarrhoeal episodes, utilising an expanded testing regimen, and to correlate clinical signs and symptoms associated with the detected pathogens.

Material and methods

The case-control study enrolled 356 patients < 5 years old with acute diarrhoea and 356 age and sex-matched healthy controls. Both cases and controls underwent a full history and physical examination, and provided two rectal swab specimens and a stool sample. Laboratory analysis included stool culture, microscopy, and indirect methods.

Results

Rotavirus was detected in 11% of patients. Enterotoxigenic Escherichia coli (ETEC), Campylobacter, Shigella, and Salmonella were detected in 7%, 3.7%, 1.1%, and 1.4% of patients, respectively; and in 11.1%, 3.1%, 0.6%, and 0.6% of controls, respectively, with no significant statistical difference. Cryptosporidium was detected in 3.9% of cases. Mixed infection was detected in 5.9% of cases and 0.9% of controls, with a significant difference (p < 0.001). No pathogen was detected in 66.3% of cases and in 83.5% of controls. Rotavirus infection was associated with recurrent vomiting, dehydration, and hospitalisation. Bacterial diarrhoea was associated with vomiting (52%) in ETEC infections, fever (80%) in Salmonella infections, mucus (100%) and blood (50%) in stools of Shigella infections, and convulsions (15%) in Campylobacter infections.

Conclusions

Rotavirus is a prominent cause of diarrhoea among Egyptian children. Despite utilising an expanded testing regimen, more work is still needed for identification of other enteropathogens that constitute other causative agents of diarrhoea.

Epidemiology and clinical manifestations of enteroaggregative Escherichia coli

Enteroaggregative Escherichia coli (EAEC) represents a heterogeneous group of E. coli strains. The pathogenicity and clinical relevance of these bacteria are still controversial. In this review, we describe the clinical significance of EAEC regarding patterns of infection in humans, transmission, reservoirs, and symptoms. Manifestations associated with EAEC infection include watery diarrhea, mucoid diarrhea, low-grade fever, nausea, tenesmus, and borborygmi. In early studies, EAEC was considered to be an opportunistic pathogen associated with diarrhea in HIV patients and in malnourished children in developing countries. In recent studies, associations with traveler's diarrhea, the occurrence of diarrhea cases in industrialized countries, and outbreaks of diarrhea in Europe and Asia have been reported. In the spring of 2011, a large outbreak of hemolytic-uremic syndrome (HUS) and hemorrhagic colitis occurred in Germany due to an EAEC O104:H4 strain, causing 54 deaths and 855 cases of HUS. This strain produces the potent Shiga toxin along with the aggregative fimbriae. An outbreak of urinary tract infection associated with EAEC in Copenhagen, Denmark, occurred in 1991; this involved extensive production of biofilm, an important characteristic of the pathogenicity of EAEC. However, the heterogeneity of EAEC continues to complicate diagnostics and also our understanding of pathogenicity.

High Incidence of Staphylococcus aureus and Norovirus Gastroenteritis in Infancy: A Single-Center, 1-Year Experience

PURPOSE

The etiology of acute gastroenteritis (AGE) has changed since the introduction of the rotavirus vaccination. The aim of this study was to clarify which common pathogens, both bacterial and viral, are currently causing AGE in infants.

METHODS

Infants with acute diarrhea were enrolled. We tested for 10 bacterial pathogens and five viral pathogens in stool specimens collected from infants with AGE. The clinical symptoms such as vomiting, mucoid or bloody diarrhea, dehydration, irritability, and poor oral intake were recorded, and laboratory data such as white blood cell count and C-reactive protein were collected. The clinical and laboratory data for the cases with bacterial pathogens and the cases with viral pathogens were compared.

RESULTS

Of 41 total infants, 21 (51.2%) were positive for at least one pathogen. Seventeen cases (41.5%) were positive for bacterial pathogens and seven cases (17.1%) were positive for viral pathogens. Staphylococcus aureus (13 cases, 31.7%) and Clostridium perfringens (four cases, 9.8%) were common bacterial pathogens. Norovirus (five cases, 12.2%) was the most common viral pathogen. Fever and respiratory symptoms were common in the isolated viral infection group (p=0.023 and 0.044, respectively), whereas other clinical and laboratory data were indistinguishable between the groups.

CONCLUSION

In our study, S. aureus (41.5%) and norovirus (12.2%) were the most common bacterial and viral pathogens, respectively, among infants with AGE.

T cells and intestinal commensal bacteria--ignorance, rejection, and acceptance

Trillions of commensal bacteria cohabit our bodies to mutual benefit. In the past several years, it has become clear that the adaptive immune system is not ignorant of intestinal commensal bacteria, but is constantly interacting with them. For T cells, the response to commensal bacteria does not appear uniform, as certain commensal bacterial species appear to trigger effector T cells to reject and control them, whereas other species elicit Foxp3(+) regulatory T (Treg) cells to accept and be tolerant of them. Here, we review our current knowledge of T cell differentiation in response to commensal bacteria, and how this process leads to immune homeostasis in the intestine.

Role of the microbiota in immunity and inflammation

The microbiota plays a fundamental role on the induction, training, and function of the host immune system. In return, the immune system has largely evolved as a means to maintain the symbiotic relationship of the host with these highly diverse and evolving microbes. When operating optimally, this immune system-microbiota alliance allows the induction of protective responses to pathogens and the maintenance of regulatory pathways involved in the maintenance of tolerance to innocuous antigens. However, in high-income countries, overuse of antibiotics, changes in diet, and elimination of constitutive partners, such as nematodes, may have selected for a microbiota that lack the resilience and diversity required to establish balanced immune responses. This phenomenon is proposed to account for some of the dramatic rise in autoimmune and inflammatory disorders in parts of the world where our symbiotic relationship with the microbiota has been the most affected.

Impact of emergency department probiotic treatment of pediatric gastroenteritis: study protocol for the PROGUT (Probiotic Regimen for Outpatient Gastroenteritis Utility of Treatment) randomized controlled trial

Background

The burden of acute gastroenteritis on children and their families continues to be enormous. Probiotics, defined as viable microbial preparations that have a beneficial effect on the health of the host, represent a rapidly expanding field. Although clinical trials in children with gastroenteritis have been performed, most have significant flaws, and guidelines do not consistently endorse their use.

Methods/Design

PROGUT is a randomized, placebo-controlled, double-blind, five-center, Canadian, emergency department trial. Children aged 3 months to 48 months who present between November 2013 and June 2017 with <72 hours of gastroenteritis symptoms will be assessed for eligibility. A total of 886 children will be randomized (1:1 allocation via an internet based, third party, randomization service) to receive 5 days of a combination probiotic agent (Lactobacillus rhamnosus and L. helveticus) or placebo. All participants, caregivers, and outcome assessors will be blinded to group assignment. The study includes three key outcomes: 1) clinical - the development of moderate to severe disease following an emergency department (ED) evaluation that employs a validated clinical score (Modified Vesikari Scale); 2) safety - side effect; and 3) mechanism - fecal secretory immunoglobulin A levels.

Discussion

Definitive data are lacking to guide the clinical use of probiotics in children with acute gastroenteritis. Hence, probiotics are rarely prescribed by North American physicians. However, the following current trends obligate an urgent assessment: 1) probiotics are sold as food supplements, and manufacturers can encourage their use while their relevance has yet to be established; 2) North American and European government agencies remain concerned about their value and safety; 3) some institutions are now recommending the routine use of probiotics; and 4) parents of affected children are often providing probiotics. With probiotic consumption increasing in the absence of solid evidence, there is a need to conduct this definitive trial to overcome the limitations of prior work in this field.

Trial registration

ClinicalTrials.gov: NCT01853124; first registered 9 May 2013.

Frequency and antimicrobial resistance of diarrhoeagenic Escherichia coli from young children in Iran

Diarrhoea continues to be one of the most common causes of morbidity and mortality among infants and children in developing countries. Diarrhoeagenic Escherichia coli (DEC) is an emerging agent among pathogens that cause diarrhoea. Between March 2011 and January 2012, a total of 600 stool specimens from children younger than 5 years of age (450 with and 150 without diarrhoea) were investigated for enteroaggregative E. coli (EAEC), enterohaemorrhagic E. coli (EHEC), enteropathogenic E. coli (EPEC) and enterotoxigenic E. coli (ETEC) using PCR. Antimicrobial susceptibility testing was performed following Clinical and Laboratory Standards Institute guidelines. The prevalence of DEC pathotypes was 30.4 % (137 patients) and 12 % (18 patients) in the diarrhoea group and the control group, respectively. The most frequently isolated pathotype in diarrhoeal children was ETEC. This pathotype was detected significantly more often in children with diarrhoea (14.4 %) than in children without diarrhoea (5.3 %). EAEC and EPEC were detected with slightly higher frequencies in children with (8 and 4.2 %, respectively) than in children without (4.6 and 2 %, respectively) (P>0.05) diarrhoea. EHEC was only detected in children with diarrhoea (3.8 %). Of the children from the diarrhoea group, 10 % were colonized with more than one DEC pathotype. The DEC isolates exhibited high-level resistance to erythromycin (100 %), azteronam (80.7 %), amoxicillin (74.4 %) and tetracycline (69.3 %), and 86.4 % of isolates were multidrug resistant. In conclusion, ETEC continues to be an important agent associated with diarrhoea in children from Tabriz, Iran.

Multi-drug-resistant enterotoxigenic and enterohemorrhagic Escherichia coli isolated from children with diarrhea

Multi-drug-resistant (MDR) diarrheagenic Escherichia coli (DEC) has rapidly spread worldwide and represents the most serious threat to the management of diarrhea in developing countries. During the period from March 2011 to January 2012, a total of 450 stool samples of diarrheal children aged 0-60 months were studied. In order to detect enterotoxigenic E. coli (ETEC) and enterohemorrhagic E. coli (EHEC) simultaneously, a mixture of four primer pairs specific for eltB, estA, vt1, and vt2 genes was used in a multiplex PCR. Antimicrobial susceptibility testing was performed as the Clinical and Laboratory Standards Institute (CLSI) guidelines. A total of 140 (31·1%) DEC were isolated from 450 stool samples. Diarrheagenic E. coli exhibited high-level resistance to aztreonam (80·7%), amoxicillin (74·4%), and tetracycline (69·3%). Also, 86·4% of E. coli isolates were resistant to at least three different classes of antimicrobial agents and considered as MDR. The frequency of ETEC and EHEC pathotypes was 46·4 and 12·1%, respectively and all of these isolates were MDR. In conclusion, MDR ETEC continues to be an important agent associated with diarrhea in children from Tabriz, Iran.

Viral co-infections are common and are associated with higher bacterial burden in children with clostridium difficile infection

Clostridium difficile infections in children are increasing. In this cohort study, we enrolled 62 children with diarrhea and C difficile. We performed polymerase chain reaction assays to detect viral agents of gastroenteritis and quantify C difficile burden. Fifteen (24%) children diagnosed as having C difficile infection had a concomitant viral co-infection. These patients tended to be younger and had a higher C difficile bacterial burden than children with no viral co-infections (median difference = 565,957 cfu/mL; P = 0.011), but were clinically indistinguishable. The contribution of viral co-infection to C difficile disease in children warrants future investigation.

Everolimus in tuberous sclerosis patients with intractable epilepsy: a treatment option?

BACKGROUND

Tuberous Sclerosis Complex (TSC) is an often severe neurodevelopmental disorder caused by overactivation of the mTOR pathway due to mutations in either the TSC1 or TSC2 genes. Seizures are the primary cause of neurologic morbidity and often refractory. The mTOR inhibitor everolimus was recently approved for the treatment of giant cell astrocytomas and renal angiomyolipomas in TSC. Whether everolimus has any direct effect on epilepsy in TSC is not known.

METHODS

Within the framework of a compassionate use trial, we evaluated the safety and efficacy of everolimus in seven patients with TSC and intractable epilepsy. We evaluated seizure frequency, seizure-free days and adverse effects including standard laboratory parameters. Seizure frequency was analysed in each patient using a non-parametric test for trend and using a Generalized Estimating Equations Model in the total patient group. The observation period was continued for nine months.

RESULTS

One patient discontinued the medication at the beginning of the observation period due to side effects (flushing). In the remaining 6 patients, we observed a reduction of seizures in 4/6 patients with a reduction of 25-100%. In addition, the percentage of seizure-free days increased in 3/4 of these patients. In 2/6 patients, no alteration of seizure frequency was noted. We observed an increase of mild infections and an increase of triglycerides and various liver function tests. We did not encounter life-threatening infections or other side effects of everolimus.

INTERPRETATION

In some patients with TSC, everolimus may have an anticonvulsant effect with a reduction in seizure frequency and increase of seizure-free days. Everolimus was well tolerated, with adverse effects similar to those reported in previous studies.

Clostridium difficile infection in children: a comprehensive review

OBJECTIVE

To provide a comprehensive review of the literature relating to Clostridium difficile (C. difficile) infection (CDI) in the pediatric population.

METHODS

Two investigators conducted independent searches of PubMed, Web of Science, and Scopus until March 31st, 2013. All databases were searched using the terms 'Clostridium difficile infection', 'Clostridium difficile associated diarrhea' 'antibiotic associated diarrhea', 'C. difficile', in combination with 'pediatric' and 'paediatric'. Articles which discussed pediatric CDI were reviewed and relevant cross references also read and evaluated for inclusion. Selection bias could be a possible limitation of this approach.

FINDINGS

There is strong evidence for an increased incidence of pediatric CDI. Increasingly, the infection is being acquired from the community, often without a preceding history of antibiotic use. The severity of the disease has remained unchanged. Several medical conditions may be associated with the development of pediatric CDI. Infection prevention and control with antimicrobial stewardship are of paramount importance. It is important to consider the age of the child while testing for CDI. Traditional therapy with metronidazole or vancomycin remains the mainstay of treatment. Newer antibiotics such as fidaxomicin appear promising especially for the treatment of recurrent infection. Conservative surgical options may be a life-saving measure in severe or fulminant cases.

CONCLUSIONS

Pediatric providers should be cognizant of the increased incidence of CDI in children. Early and judicious testing coupled with the timely institution of therapy will help to secure better outcomes for this disease.

Effector and memory T cell responses to commensal bacteria

Barrier surfaces are home to a vast population of commensal organisms that together encode millions of proteins; each of them possessing several potential foreign antigens. Regulation of immune responses to this enormous antigenic load represents a tremendous challenge for the immune system. Tissues exposed to commensals have developed elaborate systems of regulation including specialized populations of resident lymphocytes that maintain barrier function and limit potential responses to commensal antigens. However, in settings of infection and inflammation these regulatory mechanisms are compromised and specific effector responses against commensal bacteria can develop. This review discusses the circumstances controlling the fate of commensal specific T cells and how dysregulation of these responses could lead to severe pathological outcomes.

Simultaneous detection of gastrointestinal pathogens with a multiplex Luminex-based molecular assay in stool samples from diarrhoeic patients

We have evaluated the multiplex molecular method xTAG(®) Gastrointestinal Panel (GPP) for detecting pathogens in stool samples of diarrhoeic patients. We collected 440 samples from 329 patients (male:female ratio of 1.2:1), including 102 immunosuppressed adults, 50 immunosuppressed children, 56 children attending the neonatal unit and 121 children attending the emergency unit. Of these, 176 samples from 162 patients were xTAG(®) GPP positive (102 viruses, 61 bacteria and 13 parasites) and the assay was more sensitive than the conventional test for detecting rotavirus (p <0.01), noroviruses (p <0.0001), Salmonella spp. (p <0.001), Campylobacter spp. (p <0.001) and toxigenic Clostridium difficile (p 0.005). The predominant pathogens were viruses (23.2%), with rotavirus (15.9%) being the most common. Bacterial agents were detected in 13.9%; the most common was Salmonella spp. (4.8%). Parasites were detected in 2.9%; Cryptosporidium spp. (2%) was the most common. There were 31 co-infections (7% of samples), involving two pathogens in 23 (5.2%) and three pathogens in eight (1.8%) samples. There were 113 (92.6%) positive samples from the children attending the emergency unit, 25 (17%) positive samples from immunosuppressed adults, 22 (25.3%) positive samples from immunosuppressed children and 16 (19%) positive samples from children attending the neonatal unit. The low turnaround time and technical hands-on time make this multiplex technique convenient for routine use. Nevertheless, conventional bacterial culture and parasitological stool examination are still required to detect other pathogens in specific cases and to determine susceptibility to antibiotics.

Estimates of illnesses, hospitalizations and deaths caused by major bacterial enteric pathogens in young children in the United States

BACKGROUND

Many enteric pathogens disproportionately affect young children. However, higher incidences of laboratory-confirmed illness may be explained, at least in part, by higher rates of medical care-seeking and stool sample submission in this age group. We estimated the overall number of bacterial enteric illnesses among children <5 years old in the United States caused by Campylobacter, Escherichia coli O157, nontyphoidal Salmonella, Shigella and Yersinia enterocolitica.

MATERIALS AND METHODS

We used a statistical model that scaled counts of laboratory-confirmed illnesses from the Foodborne Diseases Active Surveillance Network up to an estimated number of illnesses in the United States, adjusting for the surveillance steps needed for an illness to be laboratory diagnosed (medical care sought, stool sample submitted, bacterial culture performed, laboratory tested for pathogen, laboratory test sensitivity).

RESULTS

We estimated that 5 bacterial enteric pathogens caused 291,162 illnesses each year among children <5 years old, resulting in 102,746 physician visits, 7830 hospitalizations and 64 deaths. Nontyphoidal Salmonella caused most illnesses (42%), followed by Campylobacter (28%), Shigella (21%), Y. enterocolitica (5%) and E. coli O157 (3%). The estimated annual number of physician visits ranged from 3763 for E. coli O157 to 44,369 for nontyphoidal Salmonella. Nontyphoidal Salmonella was estimated to cause most hospitalizations (4670) and deaths (38).

CONCLUSIONS

Bacterial enteric infections cause many illnesses in US children. Compared with the general population, enteric illnesses among children <5 years old are more likely to be diagnosed. However, overall rates of illness remain higher in children after adjusting for underdiagnosis in both groups.

Norovirus diversity in diarrheic children from an African-descendant settlement in Belém, Northern Brazil

Norovirus (NoV), sapovirus (SaV) and human astrovirus (HAstV) are viral pathogens that are associated with outbreaks and sporadic cases of gastroenteritis. However, little is known about the occurrence of these pathogens in relatively isolated communities, such as the remnants of African-descendant villages ("Quilombola"). The objective of this study was the frequency determination of these viruses in children under 10 years, with and without gastroenteritis, from a "Quilombola" Community, Northern Brazil. A total of 159 stool samples were obtained from April/2008 to July/2010 and tested by an enzyme immunoassay (EIA) and reverse transcription-polymerase chain reaction (RT-PCR) to detect NoV, SaV and HAstV, and further molecular characterization was performed. These viruses were detected only in the diarrheic group. NoV was the most frequent viral agent detected (19.7%-16/81), followed by SaV (2.5%-2/81) and HAstV (1.2%-1/81). Of the 16 NoV-positive samples, 14 were sequenced with primers targeting the B region of the polymerase (ORF1) and the D region of the capsid (ORF2). The results showed a broad genetic diversity of NoV, with 12 strains being classified as GII-4 (5-41.7%), GII-6 (3-25%), GII-7 (2-16.7%), GII-17 (1-8.3%) and GI-2 (1-8.3%), as based on the polymerase region; 12 samples were classified, based on the capsid region, as GII-4 (6-50%, being 3-2006b variant and 3-2010 variant), GII-6 (3-25%), GII-17 (2-16.7%) and GII-20 (1-8.3%). One NoV-strain showed dual genotype specificity, based on the polymerase and capsid region (GII-7/GII-20). This study provides, for the first time, epidemiological and molecular information on the circulation of NoV, SaV and HAstV in African-descendant communities in Northern Brazil and identifies NoV genotypes that were different from those detected previously in studies conducted in the urban area of Belém. It remains to be determined why a broader NoV diversity was observed in such a semi-isolated community.

Serum C-reactive protein (CRP) levels in young adults can be used to discriminate between inflammatory and non-inflammatory diarrhea

OBJECTIVE

To determine if the level of serum C-reactive protein (CRP) can be used to differentiate between inflammatory diarrhea and non-inflammatory diarrhea in patients with acute infectious diarrhea or acute gastrointestinal infection.

METHODS

This was a retrospective study based on medical records from a single military hospital located in Daejeon, Republic of Korea. The records of 1,085 patients who presented with abdominal pain, fever (≥ 37.8 °C), and diarrhea between May 2008 and May 2011 were reviewed, and 538 patients were selected. The eligible patients had undergone abdominal contrast tomography (CT) or colonoscopy within 3 days and blood sampling on the day of admission. The selected patients were divided into two groups on the basis of their abdominal CT or colonoscopy findings: group A, the inflammatory diarrhea group (n = 234), and group B, the non-inflammatory diarrhea group (n = 304). We then compared the clinical and laboratory characteristics of these two groups.

RESULTS

Erythrocyte sedimentation rate and CRP levels were significantly higher in group A (inflammatory diarrhea) patients than group B (non-inflammatory diarrhea) patients (16.47 ± 5.46 vs. 15.29 ± 5.72 (P < 0.05), respectively, and 4.92 ± 2.49 vs. 1.79 ± 0.95 (P < 0.05), respectively). Multivariate analysis revealed that CRP level on admission was the most important predictor of inflammatory diarrhea (OR 7.39, P < 0.05). Receiver operating characteristic analysis results also showed that CRP had the highest area-under-the-curve value (0.91; 95 % confidence interval 0.88-0.93; P < 0.05) for distinguishing inflammatory diarrhea from non-inflammatory diarrhea. At a cut-off level of 3.08 mg/dL, CRP had a sensitivity of 82 % and a specificity of 85 %.

CONCLUSIONS

CRP as a diagnostic marker of inflammatory diarrhea was superior to the other inflammatory markers and clinical characteristics we evaluated in this study. A patient's CRP level on admission may aid clinical decision-making, for example initiating empiric antibiotics therapy and/or performing additional clinical tests.

Funktions- und Laboruntersuchungen

Zur Analyse abgeatmeter Gase muss endexspiratorische Luft gewonnen werden, ohne Vermischung mit frühexspiratorischer Luft (sonst Korrektur mit Messung des CO2-Partialdrucks, s. unten). Ältere Kinder blasen nach Anhalten der Atmung über 15 s durch tiefe Ausatmung über einen Strohhalm endexspiratorische Luft in ein Glasröhrchen, das dann luftdicht verschlossen wird (Vacutainer), oder über ein Mundstück oder eine Maske direkt in ein H2-Messgerät oder in Beutel. Bei Säuglingen und Kleinkindern kann mit einer Maske oder einer Sonde, die bis zum nasopharyngealen Übergang vorgeschoben wird, mit einer Spritze atemsynchron exspiratorische Luft abgesaugt und in Vacutainer oder direkt in das Messgerät eingegeben werden. In Vacutainern sind Proben über mehr als 30 Tage stabil und können auch zur Analyse verschickt werden.