Probiotics for the prevention of Clostridium difficile-associated diarrhea in adults and children

Machine learning analysis to identify the association between risk factors and onset of nosocomial diarrhea: a retrospective cohort study

BACKGROUND

Although several risk factors for nosocomial diarrhea have been identified, the detail of association between these factors and onset of nosocomial diarrhea, such as degree of importance or temporal pattern of influence, remains unclear. We aimed to determine the association between risk factors and onset of nosocomial diarrhea using machine learning algorithms.

METHODS

We retrospectively collected data of patients with acute cerebral infarction. Seven variables, including age, sex, modified Rankin Scale (mRS) score, and number of days of antibiotics, tube feeding, proton pump inhibitors, and histamine 2-receptor antagonist use, were used in the analysis. We split the data into a training dataset and independant test dataset. Based on the training dataset, we developed a random forest, support vector machine (SVM), and radial basis function (RBF) network model. By calculating an area under the curve (AUC) of the receiver operating characteristic curve using 5-fold cross-validation, we performed feature selection and hyperparameter optimization in each model. According to their final performances, we selected the optimal model and also validated it in the independent test dataset. Based on the selected model, we visualized the variable importance and the association between each variable and the outcome using partial dependence plots.

RESULTS

Two-hundred and eighteen patients were included. In the cross-validation within the training dataset, the random forest model achieved an AUC of 0.944, which was higher than in the SVM and RBF network models. The random forest model also achieved an AUC of 0.832 in the independent test dataset. Tube feeding use days, mRS score, antibiotic use days, age and sex were strongly associated with the onset of nosocomial diarrhea, in this order. Tube feeding use had an inverse U-shaped association with the outcome. The mRS score and age had a convex downward and increasing association, while antibiotic use had a convex upward association with the outcome.

CONCLUSION

We revealed the degree of importance and temporal pattern of the influence of several risk factors for nosocomial diarrhea, which could help clinicians manage nosocomial diarrhea.

Metagenomics: aid to combat antimicrobial resistance in diarrhea

Antimicrobial resistance (AMR) has emerged as an obstacle in the supple administration of antimicrobial agents to critical diarrheal patients. Most diarrheal pathogens have developed resistance against the major classes of antibiotics commonly used for assuaging diarrheal symptoms. Antimicrobial resistance develops when pathogens acquire antimicrobial resistance genes (ARGs) through genetic recombination from commensals and pathogens. These are the constituents of the complex microbiota in all ecological niches. The recombination events may occur in the environment or in the gut. Containment of AMR can be achieved through a complete understanding of the complex and diverse structure and function of the microbiota. Its taxonomic entities serve as focal points for the dissemination of antimicrobial resistance genetic determinants. Molecular methods complemented with culture-based diagnostics have been historically implemented to document these natural events. However, the advent of next-generation sequencing has revolutionized the field of molecular epidemiology. It has revolutionized the method of addressing relevant problems like diagnosis and surveillance of infectious diseases and the issue of antimicrobial resistance. Metagenomics is one such next-generation technique that has proved to be a monumental advancement in the area of molecular taxonomy. Current understanding of structure, function and dysbiosis of microbiota associated with antimicrobial resistance was realized due to its conception. This review describes the major milestones achieved due to the advent and implementation of this new technique in the context of antimicrobial resistance. These achievements span a wide panorama from the discovery of novel microorganisms to invention of translational value.

Probiotics and prebiotics in intestinal health and disease: from biology to the clinic

Probiotics and prebiotics are microbiota-management tools for improving host health. They target gastrointestinal effects via the gut, although direct application to other sites such as the oral cavity, vaginal tract and skin is being explored. Here, we describe gut-derived effects in humans. In the past decade, research on the gut microbiome has rapidly accumulated and has been accompanied by increased interest in probiotics and prebiotics as a means to modulate the gut microbiota. Given the importance of these approaches for public health, it is timely to reiterate factual and supporting information on their clinical application and use. In this Review, we discuss scientific evidence on probiotics and prebiotics, including mechanistic insights into health effects. Strains of Lactobacillus, Bifidobacterium and Saccharomyces have a long history of safe and effective use as probiotics, but Roseburia spp., Akkermansia spp., Propionibacterium spp. and Faecalibacterium spp. show promise for the future. For prebiotics, glucans and fructans are well proven, and evidence is building on the prebiotic effects of other substances (for example, oligomers of mannose, glucose, xylose, pectin, starches, human milk and polyphenols).

Health Professionals' Knowledge of Probiotics: An International Survey

The objective of this study was to survey health professionals to investigate their knowledge of probiotics. An online survey was conducted to gather data on the knowledge of health professionals. The online survey was distributed via email and social media platforms using snowball sampling. A total of 1066 health professionals (859; 80.6% female) from 30 countries responded to the survey. Most of the respondents evaluated their knowledge of probiotics as medium (36.4%) or good (36.2%). Only 8.9% of the respondents rated it as excellent. No statistical difference in knowledge was found between male and female health professionals. Over 80% of pharmacists, allied health professionals, medical doctors and dentists, and other health professionals knew the correct definition of probiotics as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host”, whereas three quarters of registered nurses and midwives and less than two thirds of psychologists identified the correct definition. Statistically, more female than male health professionals knew the correct definition of probiotics. The most frequently recognized species of bacteria containing probiotic strains were Lactobacillus acidophilus (92%), Bifidobacterium bifidum (82%), and Lactobacillus rhamnosus (62%). The opinions on when it is best to take probiotics were different (χ² = 28.375; p < 0.001), with 90.2% of respondents identifying that probiotics have beneficial effects if taken during antibiotic therapy, 83.5% for diarrhea, 70.6% for constipation, 63.3% before traveling abroad, and 60.4% for treating allergies. Almost 79% of health professionals involved in this study have advised their patients to use probiotics and 57.5% of the respondents wanted to learn more about probiotics. All things considered, health professionals have a medium level of knowledge of probiotics, which could be improved by the implementation of targeted learning programs. As probiotics have many beneficial effects in a wide range of health areas, health professionals need to adopt the use of probiotics in clinical practice.

Relationship Between Dietary Fiber Intake and Short-Chain Fatty Acid-Producing Bacteria During Critical Illness: A Prospective Cohort Study

BACKGROUND

Dietary fiber increases short-chain fatty acid (SCFA)-producing bacteria yet is often withheld in the intensive care unit (ICU). This study evaluated the safety and effect of fiber in ICU patients with gut microbiome sampling.

METHODS

This was a retrospective study nested within a prospective cohort. Adults were included if newly admitted to the ICU and could receive oral nutrition, enteral feedings, or no nutrition. Rectal swabs were performed at admission and 72 hours later. The primary exposure was fiber intake over 72 hours, classified in tertiles and adjusted for energy intake. The primary outcome was the relative abundance (RA) of SCFA producers via 16S RNA sequencing and the tolerability of fiber.

RESULTS

In 129 patients, median fiber intake was 13.4 g (interquartile range 0-35.4 g) over 72 hours. The high-fiber group had less abdominal distension (11% high fiber vs 28% no fiber, P < .01) and no increase in diarrhea (15% high fiber vs 13% no fiber, P = .94) or other adverse events. The median RA of SCFA producers after 72 hours was 0.40%, 0.50%, and 1.8% for the no-, low-, and high-fiber groups (P = .05 for trend). After correcting for energy intake, the median RA of SCFA producers was 0.41%, 0.32%, and 2.35% in the no-, low-, and high-corrected-fiber categories (P < .01). These associations remained significant after adjusting for clinical factors including antibiotics.

CONCLUSIONS

During the 72 hours after ICU admission, fiber was well tolerated, and higher fiber intake was associated with more SCFA-producers.

A successful history: probiotics and their potential as antimicrobials

Introduction: Probiotics are living, non-pathogenic microorganisms (bacteria) that enter through diet in the human body, live during their passage through the gastrointestinal (GI) tract and are beneficial to health. They have become popular in recent years as a way of improving human health through nutrition. This review aims to discuss the efficacy of probiotics for the supportive therapy of certain clinical conditions, especially infectious diseases, as reported in a number of studies, even though some concerns about their safety still remain. Areas covered: This paper will review the history of probiotics, from ancient ages to date, and the evolution of their use in clinical practice. The study is based on both personal professional experience of the authors and a comprehensive literature analysis, including old documents from libraries, searching the related biological and clinical data on Scopus, Web of Science, PubMed, EMBASE, also using the 'cited by' and 'similar articles' options available in PubMed. Expert opinion: Not all researchers agree about the safety and real efficacy of probiotics in common conditions, especially infective diseases. However, the use of probiotics for clinical conditions that may be improved by consumption of these dietary supplements should be considered as a possible supportive therapy in select patients.

Gut Microbiome: Profound Implications for Diet and Disease

The gut microbiome plays an important role in human health and influences the development of chronic diseases ranging from metabolic disease to gastrointestinal disorders and colorectal cancer. Of increasing prevalence in Western societies, these conditions carry a high burden of care. Dietary patterns and environmental factors have a profound effect on shaping gut microbiota in real time. Diverse populations of intestinal bacteria mediate their beneficial effects through the fermentation of dietary fiber to produce short-chain fatty acids, endogenous signals with important roles in lipid homeostasis and reducing inflammation. Recent progress shows that an individual’s starting microbial profile is a key determinant in predicting their response to intervention with live probiotics. The gut microbiota is complex and challenging to characterize. Enterotypes have been proposed using metrics such as alpha species diversity, the ratio of Firmicutes to Bacteroidetes phyla, and the relative abundance of beneficial genera (e.g., Bifidobacterium, Akkermansia) versus facultative anaerobes (E. coli), pro-inflammatory Ruminococcus, or nonbacterial microbes. Microbiota composition and relative populations of bacterial species are linked to physiologic health along different axes. We review the role of diet quality, carbohydrate intake, fermentable FODMAPs, and prebiotic fiber in maintaining healthy gut flora. The implications are discussed for various conditions including obesity, diabetes, irritable bowel syndrome, inflammatory bowel disease, depression, and cardiovascular disease.

Probiotics and Clostridium Difficile: A Review of Dysbiosis and the Rehabilitation of Gut Microbiota

The basis of this paper is to address the use of probiotics as a novel approach to help treat the growing problem of antibiotic-associated diarrhea (AAD), particularly, Clostridium difficile-associated diarrhea (CDAD). Most of the available data regarding probiotics and their usefulness in treating Clostridium difficile infection (CDI) was collected and analyzed. Studies showed the effectiveness of probiotics in treating and also preventing CDI, as well as other gastrointestinal conditions such as Helicobacter pylori infection and inflammatory bowel disease. Probiotics also have, based on limited research, a comparatively minimal adverse effect profile and can aid in faster recovery from disease. Extensive research has been done on two organisms, Lactobacillus and Saccharomyces, but further research into other effective organisms are needed. More clinical trials also need to be conducted to better understand the side effect profile, optimal dosage, drug interactions, and long-term effects on gut microbiota.

The microbiome seeding debate - let's frame it around women-centred care

In a global culture that is increasingly interested in ecological interventions, probiotics, 'friendly bacteria', microbiome preservation/restoration and long-term health, there is growing awareness of the idea of seeding the vaginal microbiome in the new born after caesarean section. It is postulated as a way of restoring helpful missing microbes and preventing long term non-communicable diseases of babies delivered by caesarean section. Currently, there is a deluge of evidence being published on the human microbiome, which can be challenging to digest and absorb by scientists, clinicians and patients. The specific evidence base around this technique is at its early stages. This commentary discusses what advice is currently available from a feminist and a person-centred care perspective.

ABSTRAKT

Det er en voksende interesse internasjonalt for økologiske intervensjoner, probiotika, 'snille bakterier', bevaring/gjenoppretting av. mikrobiomet og helse i et langtidsperspektiv. I denne sammenhengen er det en økende interesse for tanken om å så det vaginale mikrobiomet (vaginal seeding) på den nyfødte etter et keisersnitt. Dette er postulert som en måte å gjenopprette manglende normalflora/mikrobiom og forebygge langvarige ikke-smittsomme sykdommer hos barn født med keisersnitt. For tiden publiseres det mye forskning om menneskets mikrobiom, noe som kan være utfordrende å fordøye og ta til seg for forskere, klinikere og pasienter. Forskningen på denne spesifikke metoden er i sin begynnelse. Denne kommentaren drøfter hvilke råd som for øyeblikket er tilgjengelige, fra et feministisk og personsentrert omsorgsperspektiv. POPULARISERT SAMMENDRAG På NORSK: Det menneskelige mikrobiomet er summen av alle bakteriene som dekker den menneskelige kroppen og det hjelper kroppen i å fungere optimalt. Når mikrobiomet forstyrres, vil kroppen kunne få betennelsesreaksjoner og allergier. I fødsel finnes de «gode» bakteriene i kvinnens vagina. (det vaginale mikrobiomet) som man tror vil være fordelaktig for babyens evne til å utvikle et sunt immunsystem. Babyer som er født med keisersnitt vil ikke bli eksponert for disse «gode» bakteriene og det kan påvirke barnets immunforsvar negativt og potensielt øke sjansen for allergier og betennelsesreaksjoner i kroppen på lang sikt. Vaginal seeding (et forsøk på å gjenopprette balansen og noen av de gode bakterier i spedbarnet gjennom å tilføre mors vaginale bakterier via en kompress som strykes over spedbarnets ansikt) Vaginal seeding er en metode som noen forskere sier muligens delvis gjenoppretter de manglende «gode» bakteriene etter et keisersnitt. Forskningen er på et tidlig stadium. Det har vært avisartikler og en film om emnet og mødre har funnet ut om vaginal seeding som en måte å gjenopprette denne delen av babyens mikrobiom. Foreldre ønsker å diskutere vaginal seeding, men på nåværende tidspunkt er helsevesenet avventende og helsepersonell er ikke godt nok informert. Denne artikkelen vil se på den pågående diskusjonen. RéSUMé: Dans une culture mondiale qui s'intéresse de plus en plus aux interventions écologiques, aux probiotiques, aux «bactéries amicales», à la préservation / restauration du microbiome et à la santé à long terme, on commence à prendre conscience de l'idée d'ensemencer le microbiome vaginal chez le nouveau-né après une césarienne. Il est postulé comme un moyen de restaurer les microbes manquants et d'aider à prévenir les maladies non transmissibles à long terme des bébés mis au monde par césarienne. Il existe actuellement un déluge de preuves sur le microbiome humain, qui peuvent être difficiles à digérer et à absorber par les scientifiques, les cliniciens et les patients. La base de preuves spécifique autour de cette technique en est à ses débuts. Ce commentaire discute des conseils actuellement disponibles dans une perspective de soins féministe et centrée sur la personne. RéSUMé SIMPLIFIé: Le microbiome humain est constitué de tous les microbes qui recouvrent le corps humain et qui aident le corps à bien fonctionner. Lorsque le microbiome est perturbé, le corps devient plus inflammatoire et est sujet aux allergies. Lors de l'accouchement, le vagin d'une mère (le microbiome vaginal) contient des "bactéries amicales" qui pourraient être bénéfiques pour l'enfant et aider le bébé à développer un système immunitaire en bonne santé. Les bébés nés par césarienne ne sont généralement pas exposés à ces «bactéries bénéfiques», ce qui pourrait affecter négativement le système immunitaire du bébé et potentiellement augmenter le risque d'allergies et d'inflammation à long terme. Selon certains scientifiques, l'ensemencement vaginal pourrait partiellement restaurer les «bactéries amies» manquantes après la césarienne. La recherche en est à ses débuts. Il y a eu des articles de journaux et un film à ce sujet, et les mères ont découvert l'existence d'un ensemencement vaginal (où une compresse placée dans le vagin de la mère pourrait être appliquée sur l'enfant après la césarienne) afin de restaurer une partie du microbiome du bébé. Les parents souhaitent discuter de l'ensemencement vaginal, mais à l'heure actuelle, les organisations médicales sont prudentes et les praticiens ne sont pas suffisamment informés. Cet article examine le débat en cours.

RESUMO

Numa cultura global que está cada vez mais interessada em intervenções ecológicas, probióticos, "bactérias amigáveis", preservação/restauração do microbioma e saúde a longo prazo, há uma crescente consciência sobre a ideia de semear o microbioma vaginal no recém-nascido após uma cirurgia cesariana. Isso está sendo postulado como uma forma de restaurar micróbios úteis que lhe faltariam e prevenir doenças não transmissíveis em longo prazo para bebês que nasceram pela via cirúrgica. Atualmente, há um aumento massivo de evidências sendo publicadas sobre o microbioma humano cuja absorção e digestão pode ser desafiadora para cientistas, clínicos e pacientes. A base específica da evidência que cerca essa técnica ainda está em estágios preliminares. Este comentário discute o aconselhamento atualmente disponível numa perspectiva feminista e centrada na pessoa. SíNTESE SIMPLIFICADA: O microbioma humano está composto por todos os micróbios que cobrem o corpo humano e que ajudam o corpo a funcionar bem. Quando o microbioma é perturbado, o corpo tem mais inflamações e maior propensão a desenvolver alergias. Ao nascimento, há "bactérias amigáveis" na vagina materna (o microbioma vaginal) que podem ser benéficas à criança e ajudar o bebê a desenvolver um sistema imunológico saudável. Bebês que nascem por cesariana usualmente não são expostos a essas "bactérias amigáveis" e isso poderá afetar negativamente o sistema imunológico do bebê, aumentando potencialmente a probabilidade de alegrias e inflamações no longo prazo. A semeadura de bactéria vaginais é um método que alguns cientistas afirmam que poderá restaurar parcialmente as "bactérias amigáveis" faltantes depois de uma cesariana. Essa pesquisa está em fase preliminar. Houve alguns artigos em jornais e um filme sobre isso, e as mães descobriram a possibilidade da semeadura vaginal (quando é feito um swab da vagina materna que é esfregado no bebê após a cesárea) para restaurar parte do microbioma do bebê. Pais desejam discutir a semeadura vaginal, mas, no momento, as organizações médicas têm sido cautelosas e os profissionais não estão adequadamente informados. Este artigo aborda o debate em andamento.

RESUMEN

En una cultura global que está cada vez más interesada en las intervenciones ecológicas, los probióticos, las "bacterias amigables", la conservación/restauración de microbiomas y la salud a largo plazo, hay una creciente conciencia de la idea de sembrar el microbioma vaginal en el recién nacido después de la cesárea. Se postula como una forma de restaurar los microbios útiles faltantes y prevenir las enfermedades no transmisibles a largo plazo de los bebés nacidos por cesárea. Actualmente, se está publicando una gran cantidad de pruebas sobre el microbioma humano, que pueden ser difíciles de digerir y absorber por parte de científicos, clínicos y pacientes. La base de la evidencia específica en torno a esta técnica se encuentra en sus primeras etapas. Este artículo analiza qué consejos están disponibles actualmente desde una perspectiva feminista y de atención centrada en la persona.

RESUMEN EN LENGUAJE SENCILLO

El microbioma humano está hecho de todos las bacterias que cubren el cuerpo humano y que ayudan al cuerpo a funcionar bien. Cuando se altera el microbioma, el cuerpo se inflama más y es propenso a las alergias. En el parto, hay "bacterias amigables" en la vagina de la madre (el microbioma vaginal) que podrían ser beneficiosas para el niño y ayudar al bebé a desarrollar un sistema inmunológico saludable. Los bebés que nacen por cesárea generalmente no se exponen a estas "bacterias amigables" y esto podría afectar negativamente el sistema inmunológico del bebé, lo que podría aumentar la probabilidad de alergias e inflamación a largo plazo. La siembra vaginal es un método que algunos científicos dicen que podría restaurar parcialmente las "bacterias amigables" que faltan después de la cesárea. La investigación se encuentra en sus primeras etapas. Han habido artículos periodísticos y una película sobre esto, y las madres se han enterado de la siembra vaginal (donde se puede frotar el niño con una torunda de la vagina de la madre después de la cesárea) para restaurar la parte del microbioma del bebé. Los padres quieren hablar sobre la siembra vaginal, pero en la actualidad las organizaciones médicas son cautelosas y los profesionales no están informados adecuadamente. Este artículo analiza el debate en curso.

Long-term durability and safety of fecal microbiota transplantation for recurrent or refractory Clostridioides difficile infection with or without antibiotic exposure

Fecal microbiota transplant (FMT) is a safe and effective treatment for recurrent or refractory Clostridioides (Clostridium) difficile infection (RCDI) in the short term. However, there are a paucity of data on long-term durability and safety of FMT. The aim of this study is to determine the long-term efficacy and safety of FMT for RCDI. Ninety-four patients underwent FMT via retention enema for RCDI between 2008 and 2012 and completed a follow-up questionnaire 4 to 8 years following the last FMT. Of these, 32 were unreachable and 37 were deceased; 23 of the remaining 25 participants completed the survey. No CDI recurrences were reported in patients treated with FMT; 12 of the 23 participants (52.2%) received at least one course of non-CDI antibiotic(s). Nine participants (40.9%) received probiotics and 4 (17.4%) received both non-CDI antibiotics and probiotics. All 23 participants rated their overall health compared with pre-FMT. Current health was considered "much better" in 17 patients (73.9%); "somewhat better" in 3 patients (13.0%); and "about the same" in 3 patients (13.0%). A total of 11 participants (47.8%) reported an increase in weight of more than 5 kg (kg) post-FMT and 9 participants (39.1%) reported no change in weight (± 5 kg). Four of the 23 participants (17.4%) reported improvement or resolution (undifferentiated colitis, n = 1; Crohn's disease, n = 2; ulcerative colitis, n = 1) of pre-existing gastrointestinal condition following FMT. Eight of 23 participants (34.8%) experienced new medical condition(s) post-FMT. The long-term efficacy (48-96 months) of FMT for RCDI appears to be durable even after non-CDI antibiotic use. Thirty percent had improvement of their pre-existing medical conditions following FMT; 73.9% reported "much better" overall health following FMT.

Growth Mode and Carbon Source Impact the Surfaceome Dynamics of Lactobacillus rhamnosus GG

Bacterial biofilms have clear implications in disease and in food applications involving probiotics. Here, we show that switching the carbohydrate source from glucose to fructose increased the biofilm formation and the total surface-antigenicity of a well-known probiotic, Lactobacillus rhamnosus GG. Surfaceomes (all cell surface-associated proteins) of GG cells grown with glucose and fructose in planktonic and biofilm cultures were identified and compared, which indicated carbohydrate source-dependent variations, especially during biofilm growth. The most distinctive differences under these conditions were detected with several surface adhesins (e.g., MBF, SpaC pilus protein and penicillin-binding proteins), enzymes (glycoside hydrolases, PrsA, PrtP, PrtR, and HtrA) and moonlighting proteins (glycolytic, transcription/translation and stress-associated proteins, r-proteins, tRNA synthetases, Clp family proteins, PepC, PepN, and PepA). The abundance of several known adhesins and candidate moonlighters, including enzymes acting on casein-derived peptides (ClpP, PepC, and PepN), increased in the biofilm cells grown on fructose, from which the surface-associated aminopeptidase activity mediated by PepC and PepN was further confirmed by an enzymatic assay. The mucus binding factor (MBF) was found most abundant in fructose grown biofilm cells whereas SpaC adhesin was identified specifically from planktonic cells growing on fructose. An additional indirect ELISA indicated both growth mode- and carbohydrate-dependent differences in abundance of SpaC, whereas the overall adherence of GG assessed with porcine mucus indicated that the carbon source and the growth mode affected mucus adhesion. The adherence of GG cells to mucus was almost completely inhibited by anti-SpaC antibodies regardless of growth mode and/or carbohydrate source, indicating the key role of the SpaCBA pilus in adherence under the tested conditions. Altogether, our results suggest that carbon source and growth mode coordinate mechanisms shaping the proteinaceous composition of GG cell surface, which potentially contributes to resistance, nutrient acquisition and cell-cell interactions under different conditions. In conclusion, the present study shows that different growth regimes and conditions can have a profound impact on the adherent and antigenic features of GG, thereby providing new information on how to gain additional benefits from this probiotic.

The Philosophy of Evidence-Based Principles and Practice in Nutrition

The practice of evidence-based nutrition involves using the best available nutrition evidence, together with clinical experience, to conscientiously work with patients' values and preferences to help them prevent (sometimes), resolve (sometimes), or cope with (often) problems related to their physical, mental, and social health. This article outlines the 3 fundamental principles of evidence-based practice as applied to the field of clinical nutrition. First, optimal clinical decision making requires awareness of the best available evidence, which ideally will come from unbiased systematic summaries of that evidence. Second, evidence-based nutrition provides guidance on how to decide which evidence is more or less trustworthy-that is, how certain can we be of our patients' prognosis, diagnosis, or of our therapeutic options? Third, evidence alone is never sufficient to make a clinical decision. Decision makers must always trade off the benefits with the risks, burden, and costs associated with alternative management strategies, and, in so doing, consider their patients' unique predicament, including their values and preferences.

Health Benefits of Heat-Killed (Tyndallized) Probiotics: An Overview

Nowadays, the oral use of probiotics is widespread. However, the safety profile with the use of live probiotics is still a matter of debate. Main risks include: Cases of systemic infections due to translocation, particularly in vulnerable patients and pediatric populations; acquisition of antibiotic resistance genes; or interference with gut colonization in neonates. To avoid these risks, there is an increasing interest in non-viable microorganisms or microbial cell extracts to be used as probiotics, mainly heat-killed (including tyndallized) probiotic bacteria (lactic acid bacteria and bifidobacteria). Heat-treated probiotic cells, cell-free supernatants, and purified key components are able to confer beneficial effects, mainly immunomodulatory effects, protection against enteropathogens, and maintenance of intestinal barrier integrity. At the clinical level, products containing tyndallized probiotic strains have had a role in gastrointestinal diseases, including bloating and infantile coli-in combination with mucosal protectors-and diarrhea. Heat-inactivated probiotics could also have a role in the management of dermatological or respiratory allergic diseases. The reviewed data indicate that heat-killed bacteria or their fractions or purified components have key probiotic effects, with advantages versus live probiotics (mainly their safety profile), positioning them as interesting strategies for the management of common prevalent conditions in a wide variety of patients´ characteristics.

Probiotics: current landscape and future horizons

In recent years there has been a rapid rise in interest for the application of probiotic supplements to act as mediators in health and disease. This appeal is predominantly due to ever-increasing evidence of the interaction of the microbiota and pathophysiological processes of disease within the human host. This narrative review considers the current landscape of the probiotic industry and its research, and discusses current pitfalls in the lack of translation from laboratory science to clinical application. Future considerations into how industry and academia must adapt probiotic research to maximize success are suggested, including more targeted application of probiotic strains dependent on individual capabilities as well as application of multiple advanced analytical technologies to further understand and accelerate microbiome science.

Gut microbiome associated with chemotherapy-induced diarrhea from the CapeOX regimen as adjuvant chemotherapy in resected stage III colorectal cancer

Background

Chemotherapy induced diarrhea (CID) is a common side effect in patients receiving chemotherapy for cancer. The aim of our study was to explore the association between gut microorganisms and CID from the CapeOX regimen in resected stage III colorectal cancer (CRC) patients.

Results

After screening and identification, 17 stool samples were collected from resected stage III CRC patients undergoing the CapeOX regimen. Bacterial 16S ribosomal RNA genes was sequenced, and a bioinformatics analysis was executed to screen for the distinctive gut microbiome and the functional metabolism associated with CID due to the CapeOX regimen. The gut microbial community richness and community diversity were lower in CID (p < 0.05 vs control group). Klebsiella pneumoniae was the most predominant species (31.22%) among the gut microbiome in CRC patients with CID. There were 75 microorganisms with statistically significant differences at the species level between the CRC patients with and without CID (LDA, linear discriminant analysis score > 2), and there were 23 pathways that the differential microorganisms might be involved in.

Conclusions

The gut microbial community structure and diversity have changed in CRC patients with CID. It may provide novel insights into the prevention and treatment of CID.

Electronic supplementary material

The online version of this article (10.1186/s13099-019-0299-4) contains supplementary material, which is available to authorized users.

Probiotics in the next-generation sequencing era

Technological developments, including massively parallel DNA sequencing, gnotobiotics, metabolomics, RNA sequencing and culturomics, have markedly propelled the field of microbiome research in recent years. These methodologies can be harnessed to improve our in-depth mechanistic understanding of basic concepts related to consumption of probiotics, including their rules of engagement with the indigenous microbiome and impacts on the human host. We have recently demonstrated that even during probiotic supplementation, resident gut bacteria in a subset of individuals resist the mucosal presence of probiotic strains, limiting their modulatory effect on the microbiome and on the host gut transcriptional landscape. Resistance is partly alleviated by antibiotics treatment, which enables probiotics to interact with the host at the gut mucosal interface, although rather than promoting reconstitution of the indigenous microbiome and of the host transcriptional profile, they inhibit these components from returning to their naïve pre-antibiotic configurations. In this commentary, we discuss our findings in the context of previous and recent works, and suggest that incorporating the state-of-the-art methods currently utilized in microbiome research into the field of probiotics may lead to improved understanding of their mechanisms of activity, as well as their efficacy and long-term safety.

Critical Appraisal of Oral Pre- and Probiotics for Caries Prevention and Care

In recent years, the concept of preventing caries-related microbial dysbiosis by enhancing the growth and survival of health-associated oral microbiota has emerged. In this article, the current evidence for the role of oral pre- and probiotics in caries prevention and caries management is discussed. Prebiotics are defined as "substrates that are selectively utilized by host microorganisms conferring a health benefit." With regard to caries, this would include alkali-generating substances such as urea and arginine, which are metabolized by some oral bacteria, resulting in ammonia production and increase in pH. While there is no evidence that urea added to chewing gums or mouth rinses significantly contributes to caries inhibition, multiple studies have shown that arginine in consumer products can exert an inhibitory effect on the caries process. Probiotics are "live microorganisms which when administrated in adequate amounts confer a health benefit on the host." Clinical trials have suggested that school-based programs with milk supplemented with probiotics and probiotic lozenges can reduce caries development in preschool children and in schoolchildren with high caries risk. Due to issues with research ethics (prebiotics) and risk of bias (prebiotics, probiotics), the confidence in the effect estimate is however limited. Further long-term clinical studies are needed with orally derived probiotic candidates, including the health-economic perspectives. In particular, the development and evaluation of oral synbiotic products, containing both prebiotics and a probiotic, would be of interest in the future management of dental caries.

Arguments for routine administration of probiotics for NEC prevention

PURPOSE OF REVIEW

Probiotic administration to premature infants for the purpose of prevention of necrotizing enterocolitis is common in many parts of the world but uncommon in the United States. The present review will emphasize recent findings in support of routine administration of probiotics to this highly vulnerable population.

RECENT FINDINGS

Additional evidence from animal models describing mechanisms of protection of probiotics in the immature gut and updated meta-analyses of randomized placebo-controlled trials and observational cohorts are presented (now including more than 40 000 premature infants from countries across the globe).

SUMMARY

The preponderance of evidence suggests that probiotic administration to premature infants is well tolerated and decreases the risk of death, necrotizing enterocolitis, and sepsis. Further comparisons of probiotic administration to placebo are not likely to alter these conclusions. Rather, future work should focus on assurance of high-quality products with demonstrated purity and viability of probiotic microbes, and future clinical trials should focus on comparisons between high-quality products and doses.

An Updated Review of Clostridium difficile Treatment in Pediatrics

Clostridium difficile infection (CDI) continues to have clinical and economic impact across all health care settings. Pediatrics accounts for a small percentage of worldwide infection; however, screening and diagnosis are confounded by asymptomatic colonization in young infants. Metronidazole and oral vancomycin have historically been the agents used to manage CDI in both pediatrics and adults. Newer agents and alternative therapies, such as fecal microbiota transplantation, may offer additional benefit. Recent guidelines updates from the Infectious Diseases Society of America and the Society for Healthcare Epidemiology of America separate pediatric and adult recommendations for epidemiology, diagnosis, and treatment. This review will discuss the risk factors, management, prevention, and updated guideline recommendations for CDI in the pediatric population.

2019 update of the WSES guidelines for management of Clostridioides (Clostridium) difficile infection in surgical patients

In the last three decades, Clostridium difficile infection (CDI) has increased in incidence and severity in many countries worldwide. The increase in CDI incidence has been particularly apparent among surgical patients. Therefore, prevention of CDI and optimization of management in the surgical patient are paramount. An international multidisciplinary panel of experts from the World Society of Emergency Surgery (WSES) updated its guidelines for management of CDI in surgical patients according to the most recent available literature. The update includes recent changes introduced in the management of this infection.

2019 update of the WSES guidelines for management of Clostridioides (Clostridium) difficile infection in surgical patients

In the last three decades, Clostridium difficile infection (CDI) has increased in incidence and severity in many countries worldwide. The increase in CDI incidence has been particularly apparent among surgical patients. Therefore, prevention of CDI and optimization of management in the surgical patient are paramount. An international multidisciplinary panel of experts from the World Society of Emergency Surgery (WSES) updated its guidelines for management of CDI in surgical patients according to the most recent available literature. The update includes recent changes introduced in the management of this infection.

Lactobacillus gasseri APC 678 Reduces Shedding of the Pathogen Clostridium difficile in a Murine Model

Clostridium difficile is a common cause of health-care acquired diarrhea, resulting in a spectrum of disease from mild diarrhea to life-threatening illness. Sixty Lactobacillus strains were screened for anti-C. difficile activity using a co-culture method. Based on their ability to inhibit C. difficile, L. gasseri APC 678 and L. rhamnosus DPC 6111 were selected for study in a murine model of C. difficile infection. L. gasseri ATCC 33323, was included as a control. It was established that, relative to control mice not fed Lactobacillus, feeding with L. gasseri APC 678 resulted in a significant reduction by day 7 (8-fold, p = 0.017) of viable C. difficile VPI 10463 in the feces of mice. In contrast, neither L. rhamnosus DPC 6111 nor L. gasseri ATCC 33323 significantly reduced fecal C. difficile shedding. Sequencing of the cecal microbiota showed that in mice fed L. gasseri APC 678 there was a significant increase in bacterial diversity across a number of indices when compared to the control or other Lactobacillus-fed groups. There was no significant change in the relative abundance of Firmicutes or Bacteroidetes in the group fed L. gasseri APC 678 relative to the control, while the groups fed L. rhamnosus DPC 6111 or L. gasseri ATCC 33323 showed a significant decrease in the relative abundance of Firmicutes (p = 0.002 and p = 0.019, respectively) and a significant increase in Bacteroidetes (p = 0.002 and p = 0.023, respectively). These results highlight the potential of L. gasseri APC 678 as a live therapeutic agent to target C. difficile infection.

Probiotics and vaginal microecology: fact or fancy?

BACKGROUND

Probiotics are live microorganisms that, when administered in adequate amounts, should confer a health benefit to the host. Media sources tend to present probiotics as an appealing health promotion method able to prevent or treat a wide variety of clinical conditions. In obstetrics and gynaecology, Lactobacilli species are mainly used to restore the physiologic vaginal microbiota in order to treat bacterial vaginosis and vulvovaginal candidiasis (VVC) and prevent preterm birth.

DISCUSSION

Several RCTs investigated the potential benefits of probiotics in gynaecological and obstetrics conditions. For all potential indications, recent specific meta-analyses have been published. Considering vulvovaginal candidiasis in non-pregnant women, probiotics slightly improved the short-term clinical and mycological cure, and reduced the 1-month relapse. However, no important impact of probiotic use was observed on long-term clinical or mycological cure. Similarly, the addition of probiotics to metronidazole for the treatment of bacterial vaginosis was not shown to provide any additional benefit. In obstetrics, using probiotics during pregnancy neither decreased nor increased the risk of preterm birth before 34 weeks or before 37 weeks. Similarly, no benefits emerged for gestational diabetes, preterm premature rupture of membrane, and small and large for gestational age infants.

CONCLUSION

Despite increasing marketing of probiotics for the treatment of vulvovaginal candidiasis and prevention of preterm birth robust evidence demonstrating a beneficial effect is scarce. Moreover, there was considerable heterogeneity among the different studies in terms of route of administration, strain/s of probiotic adopted, and length of probiotic use. Before recommending the systematic use of probiotics to treat bacterial vaginosis and VVC and prevent preterm birth, high-quality research is needed. Professional medical associations should issue recommendations defining if, when, and how probiotics should be used for gynaecological disorders.

Mechanisms of Action of Probiotics

Probiotics are living microorganisms that confer health benefits to the host when administered in adequate amounts; however, dead bacteria and their components can also exhibit probiotic properties. Bifidobacterium and strains of lactic acid bacteria are the most widely used bacteria that exhibit probiotic properties and are included in many functional foods and dietary supplements. Probiotics have been shown to prevent and ameliorate the course of digestive disorders such as acute, nosocomial, and antibiotic-associated diarrhea; allergic disorders such as atopic dermatitis (eczema) and allergic rhinitis in infants; and Clostridium difficile-associated diarrhea and some inflammatory bowel disorders in adults. In addition, probiotics may be of interest as coadjuvants in the treatment of metabolic disorders, including obesity, metabolic syndrome, nonalcoholic fatty liver disease, and type 2 diabetes. However, the mechanisms of action of probiotics, which are diverse, heterogeneous, and strain specific, have received little attention. Thus, the aim of the present work was to review the main mechanisms of action of probiotics, including colonization and normalization of perturbed intestinal microbial communities in children and adults; competitive exclusion of pathogens and bacteriocin production; modulation of fecal enzymatic activities associated with the metabolization of biliary salts and inactivation of carcinogens and other xenobiotics; production of short-chain and branched-chain fatty acids, which, in turn, have wide effects not only in the intestine but also in peripheral tissues via interactions with short-chain fatty acid receptors, modulating mainly tissue insulin sensitivity; cell adhesion and mucin production; modulation of the immune system, which results mainly in the differentiation of T-regulatory cells and upregulation of anti-inflammatory cytokines and growth factors, i.e., interleukin-10 and transforming growth factor; and interaction with the brain-gut axis by regulation of endocrine and neurologic functions. Further research to elucidate the precise molecular mechanisms of action of probiotics is warranted.

Do prophylactic probiotics prevent the incidence of Clostridium difficile colitis infection in hospitalized patients?

Clostridium difficile colitis infection is an opportunistic infection with as high as an estimated 30,000 deaths and 4.8 million dollars in healthcare costs recorded in 2011. The most common risk factor for infection is antibiotic therapy. Studies reviewed consisting of a meta-analysis of 19 randomized clinical trials demonstrate a beneficial effect of probiotics in preventing CDCI with the highest efficacy noted when initiated within 2 days of antibiotics. However, variations in dosing, initiation and species of probiotic have unknown effects in study results. The most significant correlation noted was the decreased incidence of CDCI by almost 50% when adjusting for timing of probiotic administration nearer to the first dose of antibiotics. The adverse effects of probiotics across studies were similar when comparing control and experimental groups.

PURL: Do probiotics reduce C diff risk in hospitalized patients?

A systematic review and meta-analysis says, "Yes," but that doesn't necessarily mean they will start appearing on hospital formularies.

Shaping Microbiota During the First 1000 Days of Life

The data obtained in prior studies suggest that early microbial exposition begins prior to conception and gestation. Given that the host-microbe interaction is shaped by the immune system response, it is important to understand the key immune system-microbiota relationship during the period from conception to the first years of life. The present work summarizes the available evidence concerning early microbiota exposure within the male and the female reproductive tracts at the point of conception and during gestation, focusing on the potential impact on infant development during the first 1000 days of life. Furthermore, we conclude that some dietary strategies including specific probiotics could become potentially valuable tools to modulate the gut microbiota during this early critical window of opportunity for targeted health outcomes throughout the entire lifespan.

Management of Clostridioides difficile colitis: insights for the gastroenterologist

Clostridioides difficile infection (CDI) is a common cause of diarrhea in both inpatient and outpatient settings. The last few years have seen major changes in the treatment spectrum of CDI, most notably, recommendations against using metronidazole for initial CDI, the addition of fidaxomicin and bezlotoxumab, and emergence of microbial replacement therapies. Several other therapies are undergoing clinical trials. This narrative review focuses on the treatment of CDI with a summary of literature on the newer modalities and the treatment guidelines issued by Infectious Diseases Society of America and European Society of Clinical Microbiology and Infectious Diseases.

No Impact of Probiotics to Reduce Clostridium difficile Infection in Hospitalized Patients: A Real-world Experience

We assessed the effectiveness of a Lactobacillus probiotic on rates of health care facility-onset Clostridium difficile infection (HO-CDI) in patients receiving antibiotics. A total of 1576 patients were evaluated. There was no difference in the HO-CDI incidence between those who received probiotics and those who did not (1.8% vs 0.9%; P = .16).

Lactobacillus plantarum 299v Reduces the Incidence of Clostridium difficile Infection in Nephrology and Transplantation Ward-Results of One Year Extended Study

Background: Lactobacillus plantarum 299v (LP299v) is a probiotic strain which influences on the intestinal bacterial flora. This is why, it has been introduced into clinical practice for the prevention and treatment of diarrheal disorders and alleviation of their symptoms in patients during antibiotic therapy. However, the use of probiotics in the prophylaxis of Clostridium difficile infections (CDI) in these patients is problematic. The aim of this clinical, retrospective, single-centre study was to analyse the incidence of CDI among patients hospitalized in the nephrology and transplantation ward in the period before, during and after stopping of LP299v prophylaxis. Methods: Among 5341 patients hospitalized in the nephrology and transplantation ward over a three year period, 34 patients with CDI were diagnosed and included in this analysis. From December 2013 to December 2014 all patients under antibiotic and immunosuppressive therapies received LP299v as a prophylaxis of CDI. The observation period consisted of three twelve-months periods: before, during LP299v use and after stopping of such method of CDI prevention. Results: A significant (p = 0.0003) reduction of CDI incidence during LP299v use (0.11%) was observed compared to two other periods, that is, before and after LP299v use (1.03% and 0.77%, respectively). Conclusions: Routine use of LP299v as a CDI prophylaxis may prevent CDI during antibiotics therapy in patients treated with immunosuppressive agents in nephrology and transplantation ward.

Immunological Tolerance and Function: Associations Between Intestinal Bacteria, Probiotics, Prebiotics, and Phages

Post-birth there is a bacterial assault on all mucosal surfaces. The intestinal microbiome is an important participant in health and disease. The pattern of composition and concentration of the intestinal microbiome varies greatly. Therefore, achieving immunological tolerance in the first 3-4 years of life is critical for maintaining health throughout a lifetime. Probiotic bacteria are organisms that afford beneficial health effects to the host and in certain instances may protect against the development of disease. The potential benefits of modifying the composition of the intestinal microbial cohort for therapeutic benefit is evident in the use in high risks groups such as premature infants, children receiving antibiotics, rotavirus infections in non-vaccinated children and traveler's diarrhea in adults. Probiotics and prebiotics are postulated to have immunomodulating capabilities by influencing the intestinal microbial cohort and dampening the activity of pathobiont intestinal microbes, such as Klebsiella pneumonia and Clostridia perfringens. Lactobacilli and Bifidobacteria are examples of probiotics found in the large intestine and so far, the benefits afforded to probiotics have varied in efficacy. Most likely the efficacy of probiotic bacteria has a multifactorial dependency, namely on a number of factors that include agents used, the dose, the pattern of dosing, and the characteristics of the host and the underlying luminal microbial environment and the activity of bacteriophages. Bacteriophages, are small viruses that infect and lyse intestinal bacteria. As such it can be posited that these viruses display an effective local protective control mechanism for the intestinal barrier against commensal pathobionts that indirectly may assist the host in controlling bacterial concentrations in the gut. A co-operative activity may be envisaged between the intestinal epithelia, mucosal immunity and the activity of bacteriophages to eliminate pathobiots, highlighting the potential role of bacteriophages in assisting with maintaining intestinal homeostasis. Hence bacteriophage local control of inflammation and immune responses may be an additional immunological defense mechanism that exploits bacteriophage-mucin glycoprotein interactions that controls bacterial diversity and abundance in the mucin layers of the gut. Moreover, and importantly the efficacy of probiotics may be dependent on the symbiotic incorporation of prebiotics, and the abundance and diversity of the intestinal microbiome encountered. The virome may be an important factor that determines the efficacy of some probiotic formulations.

Fecal Microbiota Transplantation for the Management of Clostridium difficile Infection

The clinical burden of Clostridium difficile infection (CDI) continues to grow. Despite the multitude of treatment options that have been developed and tested to combat the morbidity and death associated with CDI, recurrence remains common. As such, treatment modalities such as fecal microbiota transplantation (FMT) have become studied increasingly; FMT serves to transplant stool from carefully selected healthy subjects into C. difficile positive patients through a variety of delivery routes. In doing so, FMT is hypothesized to correct dysbiosis of the recipient gut microbiome addressing the root cause of the pathogenesis of C. difficile infection. A growing body of evidence shows FMT to be efficacious in this setting, and the study of FMT accordingly continues to evolve to identify novel indications for its utilization.

The Microbiome and Radiation Induced-Bowel Injury: Evidence for Potential Mechanistic Role in Disease Pathogenesis

Radiotherapy has played a major role in both the curative and palliative treatment of cancer patients for decades. However, its toxic effect to the surrounding normal healthy tissue remains a major drawback. In cases of intra-abdominal and/or pelvic malignancy, healthy bowel is inevitably included in the radiation field, causing undesirable consequences that subsequently manifest as radiation-induced bowel injury, which is associated with significant morbidity and mortality. The pathophysiology of radiation-induced bowel injury is poorly understood, although we now know that it derives from a complex interplay of epithelial injury and alterations in the enteric immune, nervous, and vascular systems in genetically predisposed individuals. Furthermore, evidence supporting a pivotal role for the gut microbiota in the development of radiation-induced bowel injury has been growing. In this review, we aim to appraise our current understanding of radiation-induced bowel injury and the role of the microbiome in its pathogenesis as well as prevention and treatment. Greater understanding of the relationship between the disease mechanism of radiation-induced bowel injury and gut microbiome might shed light on potential future prevention and treatment strategies through the modification of a patient's gut microbiome.

Identification of Burkholderia fungorum in the urine of an individual with spinal cord injury and augmentation cystoplasty using 16S sequencing: copathogen or innocent bystander?

INTRODUCTION

People with neuropathic bladder (NB) secondary to spinal cord injury (SCI) are at risk for multiple genitourinary complications, the most frequent of which is urinary tract infection (UTI). Despite the high frequency with which UTI occurs, our understanding of the role of urinary microbes in health and disease is limited. In this paper, we present the first prospective case study integrating symptom reporting, urinalysis, urine cultivation, and 16S ribosomal ribonucleic acid (rRNA) sequencing of the urine microbiome.

CASE PRESENTATION

A 55-year-old male with NB secondary to SCI contributed 12 urine samples over an 8-month period during asymptomatic, symptomatic, and postantibiotic periods. All bacteria identified on culture were present on 16S rRNA sequencing, however, 16S rRNA sequencing revealed the presence of bacteria not isolated on culture. In particular, Burkholderia fungorum was present in three samples during both asymptomatic and symptomatic periods. White blood cells of ≥5-10/high power field and leukocyte esterase ≥2 on urinalysis was associated with the presence of symptoms.

DISCUSSION

In this patient, there was a predominance of pathogenic bacteria and a lack of putative probiotic bacteria during both symptomatic and asymptomatic states. Urinalysis-defined inflammatory markers were present to a greater extent during symptomatic periods compared to the asymptomatic state, which may underscore a role for urinalysis or other inflammatory markers in differentiating asymptomatic bacteriuria from UTI in patients with NB. The finding of potentially pathogenic bacteria identified by sequencing but not cultivation, suggests a need for greater understanding of the relationships amongst bacterial species in the bacteriuric neuropathic bladder.

Pre-, pro- and synbiotics in cancer prevention and treatment-a review of basic and clinical research

There is a growing appreciation of the role of the human microbiota in the pathophysiology of cancer. Pre-, pro- and synbiotics are some of the best evidenced means of manipulating the microbiota for therapeutic benefit and their potential role in the prevention and treatment of cancer has garnered significant interest. In this review, we discuss how these agents may have oncosuppressive effects by maintaining intestinal barrier function, immunomodulation, metabolism and preventing host cell proliferation. We highlight the epidemiological and trials-based evidence supporting a role for pre-, pro- and synbiotics in the prevention of cancer. Ultimately, there is more evidence in support of these agents as adjuncts in the treatment of cancer. We discuss their roles in optimising the efficacy and/or minimising the adverse effects of chemotherapy and radiotherapy, antibiotics and surgery. Although we see significant promise in the application of pre-, pro- and synbiotics for clinical benefit in oncology patients, the field is very much in its infancy and oncologists face substantial challenges in advising their patients appropriately.

An Engineered Synthetic Biologic Protects Against Clostridium difficile Infection

Morbidity and mortality attributed to Clostridium difficile infection (CDI) have increased over the past 20 years. Currently, antibiotics are the only US FDA-approved treatment for primary C. difficile infection, and these are, ironically, associated with disease relapse and the threat of burgeoning drug resistance. We previously showed that non-toxin virulence factors play key roles in CDI, and that colonization factors are critical for disease. Specifically, a C. difficile adhesin, Surface Layer Protein A (SlpA) is a major contributor to host cell attachment. In this work, we engineered Syn-LAB 2.0 and Syn-LAB 2.1, two synthetic biologic agents derived from lactic acid bacteria, to stably and constitutively express a host-cell binding fragment of the C. difficile adhesin SlpA on their cell-surface. Both agents harbor conditional suicide plasmids expressing a codon-optimized chimera of the lactic acid bacterium's cell-wall anchoring surface-protein domain, fused to the conserved, highly adherent, host-cell-binding domain of C. difficile SlpA. Both agents also incorporate engineered biocontrol, obviating the need for any antibiotic selection. Syn-LAB 2.0 and Syn-LAB 2.1 possess positive biophysical and in vivo properties compared with their parental antecedents in that they robustly and constitutively display the SlpA chimera on their cell surface, potentiate human intestinal epithelial barrier function in vitro, are safe, tolerable and palatable to Golden Syrian hamsters and neonatal piglets at high daily doses, and are detectable in animal feces within 24 h of dosing, confirming robust colonization. In combination, the engineered strains also delay (in fixed doses) or prevent (when continuously administered) death of infected hamsters upon challenge with high doses of virulent C. difficile. Finally, fixed-dose Syn-LAB ameliorates diarrhea in a non-lethal model of neonatal piglet enteritis. Taken together, our findings suggest that the two synthetic biologics may be effectively employed as non-antibiotic interventions for CDI.

Clostridium difficile, the Difficult "Kloster" Fuelled by Antibiotics

Clostridium difficile is normally present in low numbers in a healthy adult gastro-intestinal tract (GIT). Drastic changes in the microbial population, e.g., dysbiosis caused by extensive treatment with antibiotics, stimulates the growth of resistant strains and the onset of C. difficile infection (CDI). Symptoms of infection varies from mild diarrhea to colitis (associated with dehydration and bleeding), pseudomembranous colitis with yellow ulcerations in the mucosa of the colon, to fulminant colitis (perforation of the gut membrane), and multiple organ failure. Inflamed epithelial cells and damaged mucosal tissue predisposes the colon to other opportunistic pathogens such as Clostridium perfringens, Staphylococcus aureus, Klebsiella oxytoca, Candida spp., and Salmonella spp. This may lead to small intestinal bacterial overgrowth (SIBO), sepsis, toxic megacolon, and even colorectal cancer. Many stains of C. difficile are resistant to metronidazole and vancomycin. Vaccination may be an answer to CDI, but requires more research. Success in treatment with probiotics depends on the strains used. Oral or rectal fecal transplants are partly effective, as spores in the small intestine may germinate and colonize the colon. The effect of antibiotics on C. difficile and commensal gut microbiota is summarized and changes in gut physiology are discussed. The need to search for non-antibiotic methods in the treatment of CDI and C. difficile-associated disease (CDAD) is emphasized.

Primary Prevention of Clostridium difficile-Associated Diarrhea: Current Controversies and Future Tools

PURPOSE OF REVIEW

Clostridium difficile infection (CDI) is a major cause of morbidity and mortality in hospitalized patients and rates in most places have not decreased significantly despite broad efforts by both hospitals and public health entities. This review aims to provide readers with a better understanding of the limitations of current prevention strategies. We also review potential future tools that may be available for the primary prevention of CDI in the next decade.

RECENT FINDINGS

Research over the last decade has expanded our appreciation of the role of asymptomatic shedding in the healthcare setting and in the community. This review demonstrates that poor quality data underlies even well-established guidance from national authorities on basic topics such as contact precautions, avoidance of alcohol-based hand hygiene products, CDI testing, supplemental cleaning modalities, and the use of bleach solutions. Additionally, we review research on novel preventative interventions such as identification of asymptomatic carriers, supplemental environmental cleaning technologies, vaccines, and the manipulation of the intestinal microbiome. While there is preliminary data that supports further research in all of these areas, the research is not yet robust enough on which to base local or national policy recommendations, though late-phase human clinical trials of CDI vaccine trials are ongoing. Over the last decade, researchers have begun to reassess the traditional infection prevention model for CDI. Data suggesting a greater role for asymptomatic shedders has increased our understanding of current vertical prevention techniques and is forcing researchers to look more at new processes and technologies to decrease disease incidence.

Role of the gut microbiota in nutrition and health

Ana M Valdes and colleagues discuss strategies for modulating the gut microbiota through diet and probiotics

Protective Effects of Bifidobacterial Strains Against Toxigenic Clostridium difficile

Probiotics might offer an attractive alternative to prevent and control Clostridium difficile (C. difficile) infection (CDI). Limited information is available on the ability of commercially used bifidobacterial strains to inhibit C. difficile. This study examined the anti-clostridial effects of Bifidobacterium longum JDM301, a widely used commercial probiotic strain in China, in vitro and in vivo. In vitro evaluation revealed a significant reduction in C. difficile counts when JDM301 was co-cultured with C. difficile, which was correlated with the significant decrease in clostridial toxin titres (TcdA and TcdB). Furthermore, the cell-free culture supernatants (CFS) of JDM301 inhibited C. difficile growth and degraded TcdA and TcdB. Notably, the results showed that acid pH promoted the degradation of TcdA by CFS from JDM301. Furthermore, comparative studies among 10 B. longum strains were performed, which showed that the inhibitory effect of CFS from JDM301 was similar with the other 8 B. longum strains and higher than strain BLY1. However, when it was neutralized, the significant different was lost. When present together, it was suggested that the acid pH induced by probiotics not only played important roles in the growth inhibition against C. difficile resulting in the reduction of toxins titres, but also directly promoted the degradation of clostridial toxin. In vivo studies proved that JDM301 partially relieved damage to tissues caused by C. difficile and also decreased the number of C. difficile and toxin levels. In summary, our results demonstrated that the commercial strain, JDM301 could be considered a probiotic able to exert anti-toxin capability and most of the CFS from Bifidobacterium were able to inhibit the growth of C. difficile, depending on acid pH. These results highlighted a potential that JDM301 could be helpful in preventing CDI and that most of the bifidobacterial strains could (at least partially) exert protective effects by reducing toxin titres through growth inhibition against toxigenic C. difficile.

Feasibility of a Lactobacillus casei Drink in the Intensive Care Unit for Prevention of Antibiotic Associated Diarrhea and Clostridium difficile

Background: Over 70% of patients are prescribed antibiotics during their intensive care (ICU) admission. The gut microbiome is dramatically altered early in an ICU stay, increasing the risk for antibiotic associated diarrhea (AAD) and Clostridium difficile infections (CDI). Evidence suggests that some probiotics are effective in the primary prevention of AAD and CDI. Aim: To demonstrate safety and feasibility of a probiotic drink in ICU patients. Methods: ICU patients initiated on antibiotics were recruited, and matched with contemporary controls. Study patients received two bottles daily of a drink containing 10 billion Lactobacillus casei which was bolused via feeding tube. Tolerance to probiotics and enteral nutrition, development of adverse events, and incidence of AAD was recorded. CDI rates were followed for 30 days post antibiotic treatment. Results: Thirty-two patients participated in the trial. There were no serious adverse events in the probiotic group, compared to three in the control group. AAD was documented in 12.5% of the probiotic group and 31.3% in the control group. One patient in the probiotic group developed CDI compared to three in the control group. Discussion: A probiotic containing drink can safely be delivered via feeding tube and should be considered as a preventative measure for AAD and CDI in ICU.