Safety assessment of probiotics for human use

Exopolysaccharide-producing Bifidobacterium animalis subsp. lactis strains and their polymers elicit different responses on immune cells from blood and gut associated lymphoid tissue

The effect of exopolysaccharide (EPS) producing bifidobacteria, and the EPS derived thereof, on the modulation of immune response was evaluated. Cells isolated from gut associated lymphoid tissue (GALT) and from peripheral blood mononuclear cells (PBMC) of naïve rats were used. The proliferation and cytokine production of these immune cells in the presence of the three isogenic Bifidobacterium animalis subsp. lactis strains (A1, A1dOx and A1dOxR), as well as their purified polymers, were in vitro analysed. The cytokine pattern produced by immune cells isolated from GALT showed that most levels remained stable in the presence of the three strains or their corresponding polymers. However, in PBMC the UV-inactivated bacteria induced higher levels of the ratios IFNγ/IL-17, TNFα/IL-10 and TNFα/TGFβ, and no variation in the ratio IFNγ/IL-4. Thus, B. animalis subsp. lactis strains were able to activate blood monocytes as well as T lymphocytes towards a mild inflammatory Th1 response. Furthermore, only the EPS-A1dOxR was able to stimulate a response in a similar way than its EPS-producing bacterium. Our work supports the notion that some bifidobacterial EPS could play a role in mediating the dialog of these microorganisms with the immune system. In addition, this study emphasizes the effect that the origin of the immune cells has in results obtained; this could explain the great amount of contradiction found in literature about the immunomodulation capability of EPS from probiotic bacteria.

The role of probiotics and prebiotics in inducing gut immunity

The gut immune system is influenced by many factors, including dietary components and commensal bacteria. Nutrients that affect gut immunity and strategies that restore a healthy gut microbial community by affecting the microbial composition are being developed as new therapeutic approaches to treat several inflammatory diseases. Although probiotics (live microorganisms) and prebiotics (food components) have shown promise as treatments for several diseases in both clinical and animal studies, an understanding of the molecular mechanisms behind the direct and indirect effects on the gut immune response will facilitate better and possibly more efficient therapy for diseases. In this review, we will first describe the concept of prebiotics, probiotics, and symbiotics and cover the most recently well-established scientific findings regarding the direct and indirect mechanisms by which these dietary approaches can influence gut immunity. Emphasis will be placed on the relationship of diet, the microbiota, and the gut immune system. Second, we will highlight recent results from our group, which suggest a new dietary manipulation that includes the use of nutrient products (organic selenium and Lithothamnium muelleri) and probiotics (Saccharomyces boulardii UFMG 905 and Bifidobacterium sp.) that can stimulate and manipulate the gut immune response, inducing intestinal homeostasis. Furthermore, the purpose of this review is to discuss and translate all of this knowledge into therapeutic strategies and into treatment for extra-intestinal compartment pathologies. We will conclude by discussing perspectives and molecular advances regarding the use of prebiotics or probiotics as new therapeutic strategies that manipulate the microbial composition and the gut immune responses of the host.

Production of selenium-enriched biomass by Enterococcus durans

Selenium (Se) is an essential micronutrient for several organisms, and there is an increased interest about adequate sources for dietary selenium supplementation. The aim of this study was to evaluate the selenium bioaccumulation capacity of an Enterococcus strain. The isolate LAB18s was identified as Enterococcus durans by the VITEK® 2 system and analysis of both 16S rDNA gene sequence (JX503528) and the 16S-23S rDNA intergenic spacer (ITS). After 24-h incubation, E. durans LAB18s bioaccumulated elevated Se(IV) concentrations, reaching 2.60 and 176.97 mg/g in media containing initial amounts of 15 and 240 mg/l sodium selenite, respectively. The isolate grew optimally and had high selenium bioaccumulation at initial pH of 7.0 and 30 °C. Time course studies showed that E. durans LAB18s displayed the highest bioaccumulation of Se(IV) after 6 h of incubation. Analyses from scanning electron microscopy (SEM) demonstrated the presence of filaments connecting the cells of E. durans LAB18s cultivated in the presence of sodium selenite. It was demonstrated that a considerable amount of Se(IV) was absorbed by E. durans LAB18s. Therefore, this strain may represent an alternative source of organic dietary selenium.

Bifidobacteria: their impact on gut microbiota composition and their applications as probiotics in infants

This review is aimed at describing the most recent advances in the gut microbiota composition of newborns and infants with a particular emphasis on bifidobacteria. The newborn gut microbiota is quite unstable, whereas after weaning, it becomes more stable and gets closer to the typical adult microbiota. The newborn and infant gut microbiota composition is impaired in several enteric and non-enteric pathologies. The core of this review is the description of the most recent documented applications of bifidobacteria to newborns and infants for their prevention and treatment. Acute diarrhea is the most studied disease for which bifidobacteria are applied with great success, Bifidobacterium longum and Bifidobacterium breve being the most applied species. Moreover, the most recent updates in the use of bifidobacteria for the prevention and treatment of pathologies typical of newborns, such as necrotizing enterocolitis, colics, and streptococcal infections, are presented. In addition, a number of not strictly enteric pathologies have in recent years evidenced a strict correlation with an aberrant gut microbiota in infants, in particular showing a reduced level of bifidobacteria. These diseases represent new potential opportunities for probiotic applications. Among them, allergic diseases, celiac disease, obesity, and neurologic diseases are described in this review. The preliminary use of bifidobacteria in in vitro systems and animal models is summarized as well as preliminary in vivo studies. Only after validation of the results via human clinical trials will the potentiality of bifidobacteria in the prevention and cure of these pathologies be definitely assessed.

Preventing pediatric antibiotic-associated diarrhea and Clostridium difficile infections with probiotics: A meta-analysis

AIM: To assess the efficacy and safety of probiotics for preventing pediatric: (1) antibiotic associated diarrhea and (2) Clostridium difficile (C. difficile) infections.

METHODS: On June 3, 2013, we searched PubMed (1960-2013), EMBASE (1974-2013), Cochrane Database of Systematic Reviews (1990-2013), CINAHL (1981-2013), AMED (1985-2013), and ISI Web of Science (2000-2013). Additionally, we conducted an extensive grey literature search including contact with National Institutes of Health Clinical Trials Registry, abstracts from annual infectious disease and gastroenterology meetings, experts in the field and correspondence with authors. The primary outcomes were the incidence of antibiotic-associated diarrhea (AAD) and C. difficile infections (CDI). Dichotomous outcomes (e.g., incidence of AAD or CDI) were pooled using a random-effects model to calculate the relative risk and corresponding 95% confidence interval (95%CI) and weighted on study quality. To explore possible explanations for heterogeneity, a priori subgroup analysis were conducted on probiotic strain type, daily dose, quality of study and safety of probiotics. The overall quality of the evidence supporting each outcome was assessed using the grading of recommendations, assessment, development and evaluation criteria.

RESULTS: A total of 1329 studies were identified with 22 trials (23 treatment arms and 4155 participants) meeting eligibility requirements for our review of prevention of AAD and 5 trials (1211 participants) for the prevention of CDI. Trials in adult populations, trials of uncertain antibiotic exposure or studies which did not provide incidence of AAD were excluded. We found 12 trials testing a single strain of probiotic and 10 trials testing a mixture of probiotic strains. Probiotics (all strains combined) significantly reduced the incidence of pediatric AAD (pooled RR = 0.42, 95%CI: 0.33-0.53) and significantly reduced pediatric CDI (pooled RR = 0.35, 95%CI: 0.13-0.92). Of the two strains with multiple trials, both significantly reduced pediatric AAD: Saccharomyces boulardii lyo (pooled RR = 0.43, 95%CI: 0.32-0.60) and Lactobacillus rhamnosus GG (pooled RR = 0.36, 95%CI: 0.19-0.69). There was no significant effect by type of antibiotic, or by duration or dose of probiotic. No adverse events associated were found in the 22 controlled trials relating to the use of probiotics.

CONCLUSION: This meta-analysis found that probiotics significantly prevented pediatric antibiotic associated diarrhea and pediatric CDI, but the efficacy varies significantly by the strain of the probiotic.

Bioengineered probiotics, a strategic approach to control enteric infections

Enteric infections account for high morbidity and mortality and are considered to be the fifth leading cause of death at all ages worldwide. Seventy percent of all enteric infections are foodborne. Thus significant efforts have been directed toward the detection, control and prevention of foodborne diseases. Many antimicrobials including antibiotics have been used for their control and prevention. However, probiotics offer a potential alternative intervention strategy owing to their general health beneficial properties and inhibitory effects against foodborne pathogens. Often, antimicrobial probiotic action is non-specific and non-discriminatory or may be ineffective. In such cases, bioengineered probiotics expressing foreign gene products to achieve specific function is highly desirable. In this review we summarize the strategic development of recombinant bioengineered probiotics to control enteric infections, and to examine how scientific advancements in the human microbiome and their immunomodulatory effects help develop such novel and safe bioengineered probiotics.

Systematic review: probiotics in the management of lower gastrointestinal symptoms in clinical practice -- an evidence-based international guide

BACKGROUND

Evidence suggests that the gut microbiota play an important role in gastrointestinal problems.

AIM

To give clinicians a practical reference guide on the role of specified probiotics in managing particular lower gastrointestinal symptoms/problems by means of a systematic review-based consensus.

METHODS

Systematic literature searching identified randomised, placebo-controlled trials in adults; evidence for each symptom/problem was graded and statements developed (consensus process; 10-member panel). As results cannot be generalised between different probiotics, individual probiotics were identified for each statement.

RESULTS

Thirty seven studies were included; mostly on irritable bowel syndrome [IBS; 19 studies; treatment responder rates: 18-80% (specific probiotics), 5-50% (placebo)] or antibiotic-associated diarrhoea (AAD; 10 studies). Statements with 100% agreement and 'high' evidence levels indicated that: (i) specific probiotics help reduce overall symptom burden and abdominal pain in some IBS patients; (ii) in patients receiving antibiotics/Helicobacter pylori eradication therapy, specified probiotics are helpful as adjuvants to prevent/reduce the duration/intensity of AAD; (iii) probiotics have favourable safety in patients in primary care. Items with 70-100% agreement and 'moderate' evidence were: (i) specific probiotics help relieve overall symptom burden in some patients with diarrhoea-predominant IBS, and reduce bloating/distension and improve bowel movement frequency/consistency in some IBS patients and (ii) with some probiotics, improved symptoms have led to improvement in quality of life.

CONCLUSIONS

Specified probiotics can provide benefit in IBS and antibiotic-associated diarrhoea; relatively few studies in other indications suggested benefits warranting further research. This study provides practical guidance on which probiotic to select for a specific problem.

Supercritical CO2 interpolymer complex encapsulation improves heat stability of probiotic bifidobacteria

The probiotic industry faces the challenge of retention of probiotic culture viability as numbers of these cells within their products inevitably decrease over time. In order to retain probiotic viability levels above the therapeutic minimum over the duration of the product's shelf life, various methods have been employed, among which encapsulation has received much interest. In line with exploitation of encapsulation for protection of probiotics against adverse conditions, we have previously encapsulated bifidobacteria in poly-(vinylpyrrolidone)-poly-(vinylacetate-co-crotonic acid) (PVP:PVAc-CA) interpolymer complex microparticles under supercritical conditions. The microparticles produced had suitable characteristics for food applications and also protected the bacteria in simulated gastrointestinal fluids. The current study reports on accelerated shelf life studies of PVP:PVAc-CA encapsulated Bifidobacterium lactis Bb12 and Bifidobacterium longum Bb46. Samples were stored as free powders in glass vials at 30 °C for 12 weeks and then analysed for viable counts and water activity levels weekly or fortnightly. Water activities of the samples were within the range of 0.25-0.43, with an average a(w) = 0.34, throughout the storage period. PVP:PVAc-CA interpolymer complex encapsulation retained viable levels above the recommended minimum for 10 and 12 weeks, for B. longum Bb46 and B. lactis Bb12, respectively, thereby extending their shelf lives under high storage temperature by between 4 and 7 weeks. These results reveal the possibility for manufacture of encapsulated probiotic powders with increased stability at ambient temperatures. This would potentially allow the supply of a stable probiotic formulation to impoverished communities without proper storage facilities recommended for most of the currently available commercial probiotic products.

Microbial characterization of probiotics--advisory report of the Working Group "8651 Probiotics" of the Belgian Superior Health Council (SHC)

When ingested in sufficient numbers, probiotics are expected to confer one or more proven health benefits on the consumer. Theoretically, the effectiveness of a probiotic food product is the sum of its microbial quality and its functional potential. Whereas the latter may vary much with the body (target) site, delivery mode, human target population, and health benefit envisaged microbial assessment of the probiotic product quality is more straightforward. The range of stakeholders that need to be informed on probiotic quality assessments is extremely broad, including academics, food and biotherapeutic industries, healthcare professionals, competent authorities, consumers, and professional press. In view of the rapidly expanding knowledge on this subject, the Belgian Superior Health Council installed Working Group "8651 Probiotics" to review the state of knowledge regarding the methodologies that make it possible to characterize strains and products with purported probiotic activity. This advisory report covers three main steps in the microbial quality assessment process, i.e. (i) correct species identification and strain-specific typing of bacterial and yeast strains used in probiotic applications, (ii) safety assessment of probiotic strains used for human consumption, and (iii) quality of the final probiotic product in terms of its microbial composition, concentration, stability, authenticity, and labeling.

Lactobacillus: host-microbe relationships

Lactobacilli are a subdominant component of the human intestinal microbiota that are also found in other body sites, certain foods, and nutrient-rich niches in the free environment. They represent the types of microorganisms that mammalian immune systems have learned not to react to, which is recognized as a potential driving force in the evolution of the human immune system. Co-evolution of lactobacilli and animals provides a rational basis to postulate an association with health benefits. To further complicate a description of their host interactions, lactobacilli may rarely cause opportunistic infections in compromised subjects. In this review, we focus primarily on human-Lactobacillus interactions. We overview the microbiological complexity of this extraordinarily diverse genus, we describe where lactobacilli are found in or on humans, what responses their presence elicits, and what microbial interaction and effector molecules have been identified. The rare cases of Lactobacillus septicaemia are explained in terms of the host impairment required for such an outcome. We discuss possibilities for exploitation of lactobacilli for therapeutic delivery and mucosal vaccination.

Genomic and phenotypic evidence for probiotic influences of Lactobacillus gasseri on human health

Certain lactic acid bacteria (LAB) have the capacity to occupy mucosal niches of humans, including the oral cavity, gastrointestinal tract, and vagina. Among commensal, LAB are species of the acidophilus complex, which have proven to be a substantial reservoir for microorganisms with probiotic attributes. Specifically, Lactobacillus gasseri is an autochthonous microorganism which has been evaluated for probiotic activity based on the availability of genome sequence and species-specific adaptation to the human mucosa. Niche-related characteristics of L. gasseri contributing to indigenous colonization include tolerance of low pH environments, resistance to bile salts, and adhesion to the host epithelium. In humans, L. gasseri elicits various health benefits through its antimicrobial activity, bacteriocin production, and immunomodulation of the innate and adaptive systems. The genomic and empirical evidence supporting use of L. gasseri in probiotic applications is substantiated by clinical trial data displaying maintenance of vaginal homeostasis, mitigation of Helicobacter pylori infection, and amelioration of diarrhea.

Lactocepin as a protective microbial structure in the context of IBD

Probiotics have been shown to exert beneficial effects in the context of different diseases including inflammatory bowel diseases (IBD). However, clinical use of probiotics is hampered by lack of understanding of the protective mechanisms and by safety concerns regarding the application of high numbers of live bacteria in patients. The identification of protective microbial structure-function relationships might enable to overcome these restraints and might lead to innovative therapies using the isolated active microbial structures. In our study, we aimed to characterize the protective mechanisms of VSL#3, a clinically relevant probiotic mixture in IBD. We found Lactobacillus casei/paracasei-produced lactocepin to selectively degrade pro-inflammatory chemokines, resulting in reduced immune cell infiltration and reduced inflammation in experimental IBD models. As immune cell recruitment is a major proinflammatory mechanism our findings suggest that lactocepin might be of broad therapeutic relevance in an array of inflammatory diseases like IBD, allergic skin inflammation and psoriasis.

Probiotics in the management of irritable bowel syndrome and inflammatory bowel disease

PURPOSE OF REVIEW

There is direct evidence that the pathogenesis of inflammatory bowel disease (IBD) involves the gastrointestinal microbiota and some evidence that the microbiota might also play a similar role in irritable bowel syndrome (IBS). The aim of this article is to review the emerging evidence for the mechanisms and effectiveness of probiotics in the management of these disorders.

RECENT FINDINGS

The composition of the gastrointestinal microbiota is strongly influenced by factors including age, diet and disease. Probiotics may be effective through their impact on the host gastrointestinal microbiota and promotion of mucosal immunoregulation. Probiotics are considered to be well tolerated, although the quality of studies and health claims has been variable. There are many short-term studies demonstrating the effectiveness of probiotics in IBS, although recommendations should be made for specific strains and for specific symptoms. Within IBD, a number of trials have shown the benefits of a range of probiotics in pouchitis and in ulcerative colitis, although current evidence in Crohn's disease is less promising.

SUMMARY

Clearly, some probiotics have considerable potential in the management of IBS and IBD; however, the benefits are strain specific. High-quality trials of probiotics in gastrointestinal disorders as well as laboratory investigations of their mechanism of action are required in order to understand who responds and why.

Probiotics: a new frontier for infection control

Probiotics are live micro-organisms administered to provide health benefits. Probiotics are being increasingly used in healthcare contexts both in research studies and routine practice, for example in neonatal intensive care. Currently there is a paucity of guidelines or regulations governing the mitigation of infection risks associated with the use of probiotics in clinical practice. We propose a number of recommendations to mitigate risks. These include the communication of probiotic use to appropriate stakeholders, ensuring that routine laboratories can identify and test the susceptibility of probiotic strains, assuring standards for preparation and administration, and ensuring surveillance designed to capture adverse events.

An oral preparation of Lactobacillus acidophilus for the treatment of uncomplicated acute watery diarrhoea in Vietnamese children: study protocol for a multicentre, randomised, placebo-controlled trial

BACKGROUND

Diarrhoeal disease is a major global health problem, particularly affecting children under the age of 5 years. Besides oral rehydration solution, probiotics are also commonly prescribed to children with acute watery diarrhoea in some settings. Results from randomised clinical trials (RCTs) in which investigators studied the effect of probiotics on diarrhoeal symptoms have largely shown a positive effect; yet, the overall quality of the data is limited. In Vietnam, probiotics are the most frequently prescribed treatment for children hospitalised with acute watery diarrhoea, but there is little justification for this treatment in this location. We have designed a RCT to test the hypothesis that an oral preparation of Lactobacillus acidophilus is superior to placebo in the treatment of acute watery diarrhoea in Vietnamese children.

METHODS

This RCT was designed to study the effect of treatment with L. acidophilus (4 × 109 colony-forming units/day) for 5 days for acute watery diarrhoea against a placebo in 300 children ages 9 to 60 months admitted to hospitals in Vietnam. Clinical and laboratory data plus samples will be collected on admission, daily during hospitalisation, at discharge, and at follow-up visits for a subset of participants. The primary end point will be defined as the time from the first dose of study medication to the start of the first 24-hour period without diarrhoea as assessed by the on-duty nurse. Secondary endpoints include the time to cessation of diarrhoea as recorded by parents or guardians in an hourly checklist, stool frequency over the first 3 days, treatment failure, rotavirus and norovirus viral loads, and adverse events.

DISCUSSION

The existing evidence for the use of probiotics in treating acute watery diarrhoea seems to favour their use. However, the size of the effect varies across publications. An array of different probiotic organisms, doses, treatment durations, study populations, designs, settings, and aetiologies have been described. In this trial, we will investigate whether probiotics are beneficial as an adjuvant treatment for children with acute watery diarrhoea in Vietnam, with the aim of guiding clinical practice through improved regional evidence.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN88101063.

An oral preparation of Lactobacillus acidophilus for the treatment of uncomplicated acute watery diarrhoea in Vietnamese children: study protocol for a multicentre, randomised, placebo-controlled trial

BACKGROUND

Diarrhoeal disease is a major global health problem, particularly affecting children under the age of 5 years. Besides oral rehydration solution, probiotics are also commonly prescribed to children with acute watery diarrhoea in some settings. Results from randomised clinical trials (RCTs) in which investigators studied the effect of probiotics on diarrhoeal symptoms have largely shown a positive effect; yet, the overall quality of the data is limited. In Vietnam, probiotics are the most frequently prescribed treatment for children hospitalised with acute watery diarrhoea, but there is little justification for this treatment in this location. We have designed a RCT to test the hypothesis that an oral preparation of Lactobacillus acidophilus is superior to placebo in the treatment of acute watery diarrhoea in Vietnamese children.

METHODS

This RCT was designed to study the effect of treatment with L. acidophilus (4 × 109 colony-forming units/day) for 5 days for acute watery diarrhoea against a placebo in 300 children ages 9 to 60 months admitted to hospitals in Vietnam. Clinical and laboratory data plus samples will be collected on admission, daily during hospitalisation, at discharge, and at follow-up visits for a subset of participants. The primary end point will be defined as the time from the first dose of study medication to the start of the first 24-hour period without diarrhoea as assessed by the on-duty nurse. Secondary endpoints include the time to cessation of diarrhoea as recorded by parents or guardians in an hourly checklist, stool frequency over the first 3 days, treatment failure, rotavirus and norovirus viral loads, and adverse events.

DISCUSSION

The existing evidence for the use of probiotics in treating acute watery diarrhoea seems to favour their use. However, the size of the effect varies across publications. An array of different probiotic organisms, doses, treatment durations, study populations, designs, settings, and aetiologies have been described. In this trial, we will investigate whether probiotics are beneficial as an adjuvant treatment for children with acute watery diarrhoea in Vietnam, with the aim of guiding clinical practice through improved regional evidence.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN88101063.

Development of intestinal microbiota in infants and its impact on health

Throughout the human lifetime, the intestinal microbiota performs vital functions, such as barrier function, metabolic reactions, trophic effects, and maturation of the host's innate and adaptive immune responses. Development of the intestinal microbiota in infants is characterized by rapid and large changes in microbial abundance, diversity, and composition. These changes are influenced by medical, cultural, and environmental factors such as mode of delivery, diet, familial environment, diseases, and therapies used. Thus, it is nearly impossible to define a universal standard for intestinal colonization and development of the intestinal microbiota. This review discusses recent data on the early colonization of the gut by microbial species, development of the intestinal microbiota, and its impact on health.

Sources, isolation, characterisation and evaluation of probiotics

According to the FAO and the WHO, probiotics are 'live microorganisms which, when administered in adequate amounts, confer a health benefit on the host'. The strains most frequently used as probiotics include lactic acid bacteria and bifidobacteria, which are isolated from traditional fermented products and the gut, faeces and breast milk of human subjects. The identification of microorganisms is the first step in the selection of potential probiotics. The present techniques, including genetic fingerprinting, gene sequencing, oligonucleotide probes and specific primer selection, discriminate closely related bacteria with varying degrees of success. Additional molecular methods, such as denaturing gradient gel electrophoresis/temperature gradient gel electrophoresis and fluorescence in situ hybridisation, are employed to identify and characterise probiotics. The ability to examine fully sequenced genomes has accelerated the application of genetic approaches to the elucidation of the functional roles of probiotics. One of the best-demonstrated clinical benefits of probiotics is the prevention and treatment of acute and antibiotic-associated diarrhoea;however, there is mounting evidence for a potential role for probiotics in the treatment of allergies and intestinal, liver and metabolic diseases. There are various mechanisms by which probiotics exert their beneficial effects: regulation of intestinal permeability, normalisation of host intestinal microbiota, improvement of gut immune barrier function, and adjustment between pro- and anti-inflammatory cytokines. The number of studies carried out to test the effects of probiotics in vitro and in animals is enormous. However, the most reliable method of assessing the therapeutic benefits of any probiotic strain is the use of randomised, placebo-controlled trials, which are reviewed in this article [corrected].

Investigation of inpatient probiotic use at an academic medical center

OBJECTIVES

Despite the widespread use of probiotics, there are limited data regarding their safety. The aims of this study were to characterize inpatient probiotic use and to determine the incidence of probiotic-related bloodstream infections due to Lactobacillus acidophilus/Lactobacillus bulgaricus.

METHODS

This study was a two-part retrospective study conducted at a large academic medical center. The first part was the characterization of probiotic use during 2007-2008, which included the type of prescribing provider, choice of probiotic prescribed, indications for use, and presence of potential risk factors for probiotic infection among recipients; the second part was the determination of the incidence of probiotic-related bloodstream infections due to L. acidophilus/L. bulgaricus for September 2000-August 2008.

RESULTS

Probiotic use was uncommon (0.4%). Ninety-six percent of patients received Lactobacillus-based compounds. Use was common in patients at theoretical risk for probiotic infection. The maximum estimated incidence of probiotic-related bacteremia due to L. acidophilus/L. bulgaricus during the 8-year period was 0.2%.

CONCLUSIONS

L. acidophilus/L. bulgaricus probiotic use at our institution appeared to be associated with a minimal risk of probiotic-related infection, even though it was used at a high frequency among inpatients who could be considered at high theoretical risk for probiotic-related bloodstream infection.

A commentary on the safety of probiotics

Probiotics have a long record of safety, which relates primarily to lactobacilli and bifidobacteria. Experience with other forms of probiotic is more limited. There is no such thing as zero risk, particularly in the context of certain forms of host susceptibility. There is poor public understanding of the concept of risk, in general, and risk/benefit analysis, in particular. Uncertainty persists regarding the potential for transfer of antibiotic resistance with probiotics, but the risk seems to be low with currently available probiotic products. As with other forms of therapeutics, the safety of probiotics should be considered on a strain-by-strain basis.

Anaphylactic reaction to probiotics. Cow's milk and hen's egg allergens in probiotic compounds

BACKGROUND

Probiotics are used in the treatment of allergic diseases. We investigated the safety of probiotics for subjects with food allergy.

MATERIAL AND METHODS

Labels of probiotics commercially available in Spain were examined to assess their content of cow's milk or hen's egg. Skin prick tests with these compounds (20 mg/ml) were performed in five children allergic to cow's milk, five children allergic to hen's white egg, and five control subjects non-allergic to food. Three serum pools: I (positive-specific IgE to cow's milk and hen's egg white proteins), II (positive-specific IgE to cow's milk and negative to hen's egg white proteins), and III (negative-specific IgE to cow's milk and positive to hen's egg white proteins) were used to detect cow's milk and hen's egg white allergens in probiotics. ImmunoCAP(®) (Phadia), in-house ELISA, SDS-PAGE immunoblotting, and inhibition studies of these assays were performed. Proteins were quantified by enzyme-immunoassay.

RESULTS

Eleven probiotics were studied. No label advertised about egg content, eight labels warned about lactose, lactic acid or cow's milk, one label claimed to be milk-free, and two gave no information. Cow's milk proteins were detected, by at least one lab technique, in 10/11 probiotics, three over 2.5 mg/kg (21, 52, 112 mg/kg). Hen's egg white proteins were detected in 3/11 probiotics, only one had more than 2.5 mg/kg (47 mg/kg).

CONCLUSION

Probiotic compounds may contain hidden allergens of food and may not be safe for subjects with allergy to cow's milk or hen's egg.

Probiotics: a potential role in the prevention of gestational diabetes?

The gut microbiome has a complex relationship with host metabolism and immune function. Host health and diet influence the composition of the gut microbiome, and conversely, different microbiome compositions influence host metabolism. Gestational diabetes mellitus is increasingly common and has serious implications for maternal and foetal health both during pregnancy and later in life. To date, clinical trials of exercise and dietary interventions to prevent the onset of gestational diabetes have had heterogeneous results and have proven disappointingly difficult. Alternative prevention strategies of gestational diabetes mellitus need to be considered and trialled in a placebo-controlled manner in combination with dietary and behavioural measures. One such potential preventative therapy is probiotic supplementation, that is, ingestion of specific bacterial strains with beneficial effects on the host. Probiotic supplements have been shown to improve metabolism by increasing host insulin sensitivity, cholesterol metabolism and also have a beneficial effect on the immune system. This discussion paper examines the evidence for the influence of the gut microbiome on host metabolism and the potential metabolic impact of probiotic supplementation, with particular regard for the evidence surrounding a possible use of probiotic supplements for the prevention of gestational diabetes. Probiotics offer the tantalising possibility of a feasible intervention for the prevention of gestational diabetes and improvement of metabolic syndromes, but there is a pressing need for further studies of the mechanisms underlying the apparent metabolic benefits and for the use of randomised controlled trials to allow examination of the effectiveness of probiotic supplementation in this setting.

Genotoxicity of Escherichia coli Nissle 1917 strain cannot be dissociated from its probiotic activity

Oral administration of the probiotic bacterium Escherichia coli Nissle 1917 improves chronic inflammatory bowel diseases, but the molecular basis for this therapeutic efficacy is unknown. E. coli Nissle 1917 harbors a cluster of genes coding for the biosynthesis of hybrid nonribosomal peptide-polyketide(s). This biosynthetic pathway confers the ability for bacteria to induce DNA double strand breaks in eukaryotic cells. Here we reveal that inactivation of the clbA gene within this genomic island abrogated the ability for the strain to induce DNA damage and chromosomal abnormalities in non-transformed cultured rat intestinal epithelial cells but is required for the probiotic activity of E. coli Nissle 1917. Thus, evaluation of colitis severity induced in rodent fed with E. coli Nissle 1917 or an isogenic non-genotoxic mutant demonstrated the need for a functional biosynthetic pathway both in the amelioration of the disease and in the modulation of cytokine expression. Feeding rodents with a complemented strain for which genotoxicity was restored confirmed that this biosynthetic pathway contributes to the health benefits of the probiotic by modulating its immunomodulatory properties. Our data provide additional evidence for the benefit of this currently used probiotic in colitis but remind us that an efficient probiotic may also have side effects as any other medication.

Is "processed" a four-letter word? The role of processed foods in achieving dietary guidelines and nutrient recommendations

This paper, based on the symposium "Is 'Processed' a Four-Letter Word? The Role of Processed Foods in Achieving Dietary Guidelines and Nutrient Recommendations in the U.S." describes ongoing efforts and challenges at the nutrition-food science interface and public health; addresses misinformation about processed foods by showing that processed fruits and vegetables made important dietary contributions (e.g., fiber, folate, potassium, vitamins A and C) to nutrient intake among NHANES 2003-2006 participants, that major sources of vitamins (except vitamin K) were provided by enrichment and fortification and that enrichment and fortification helped decrease the percentage of the population below the Estimated Average Requirement for vitamin A, thiamin, folate, and iron; describes how negative consumer perceptions and consumer confusion about processed foods led to the development of science-based information on food processing and technology that aligns with health objectives; and examines challenges and opportunities faced by food scientists who must balance consumer preferences, federal regulations, and issues surrounding food safety, cost, unintended consequences, and sustainability when developing healthful foods that align with dietary guidelines.

Characterization of Bifidobacterium spp. strains for the treatment of enteric disorders in newborns

Several studies support the use of probiotics for the treatment of minor gastrointestinal problems in infants. Positive effects on newborn colics have been evidenced after administration of Lactobacillus strains, whereas no studies have been reported regarding the use of bifidobacteria for this purpose. This work was therefore aimed at the characterization of Bifidobacterium strains capable of inhibiting the growth of pathogens typical of the infant gastrointestinal tract and of coliforms isolated from colic newborns. Among the 46 Bifidobacterium strains considered, 16 showed high antimicrobial activity against potential pathogens; these strains were further characterized from a taxonomic point of view, for the presence and transferability of antibiotic resistances, for citotoxic effects and adhesion to nontumorigenic gut epithelium cell lines. Moreover, their ability to stimulate gut health by increasing the metabolic activity and the immune response of epithelial cells was also studied. The examination of all these features allowed to identify three Bifidobacterium breve strains and a Bifidobacterium longum subsp. longum strain as potential probiotics for the treatments of enteric disorders in newborns such as infantile colics. A validation clinical trial involving the selected strains is being planned.

A multicentre randomised controlled trial evaluating lactobacilli and bifidobacteria in the prevention of antibiotic-associated diarrhoea in older people admitted to hospital: the PLACIDE study protocol

Background

Antibiotic associated diarrhoea complicates 5–39% of courses of antibiotic treatment. Major risk factors are increased age and admission to hospital. Of particular importance is C. difficile associated diarrhoea which occurs in about 4% of antibiotic courses and may result in severe illness, death and high healthcare costs. The emergence of the more virulent 027 strain of C. difficile has further heightened concerns. Probiotics may prevent antibiotic associated diarrhoea by several mechanisms including colonization resistance through maintaining a healthy gut flora.

Methods

This study aims to test the hypothesis that administration of a probiotic comprising two strains of lactobacilli and two strains of bifidobacteria alongside antibiotic treatment prevents antibiotic associated diarrhoea. We have designed a prospective, parallel group trial where people aged 65 years or more admitted to hospital and receiving one or more antibiotics are randomly allocated to receive either one capsule of the probiotic or a matching placebo daily for 21 days. The primary outcomes are the frequency of antibiotic associated and C. difficile diarrhoea during 8–12 weeks follow-up. To directly inform routine clinical practice, we will recruit a sufficient number of patients to demonstrate a 50% reduction in the frequency of C. difficile diarrhoea with a power of 80%. To maximize the generalizability of our findings and in view of the well-established safety record of probiotics, we will recruit a broad range of medical and surgical in-patients from two different health regions within the UK.

Discussion

Antibiotic associated diarrhoea constitutes a significant health burden. In particular, current measures to prevent and control C. difficile diarrhoea are expensive and disrupt clinical care. This trial may have considerable significance for the prevention of antibiotic associated diarrhoea in hospitals.

Trial registration

International Standard Randomised Controlled Trial Number Register ISRCTN70017204.

Lactobacillus rhamnosus bacteremia: an emerging clinical entity

Lactobacillus spp. are ubiquitous commensals of the normal human flora that are only occasionally found in clinical infections. Their role in human disease is established for infectious endocarditis but is controversial for other infections. We sought to characterize clinically associated Lactobacillus spp. We conducted a retrospective study, which consisted of the screening of Lactobacillus isolates obtained in our laboratory from January 2004 to December 2009. The polymerase chain reaction (PCR) assay was selected as the gold standard method. The isolates were first identified using API Coryne strips, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and 16S rRNA gene sequencing. Lactobacillus tuf gene-based identification was used when the 16S rRNA results were inconclusive. Among the 60 strains of Lactobacillus spp. obtained in our laboratory, L. rhamnosus was the most commonly isolated species and was found in blood cultures from 16 patients. Combined with 45 patients reported in the literature, we found that patients presenting with L. rhamnosus bacteremia experienced nosocomial infections associated with both immunosuppression (66 %) and catheters (83 %).

Probiotics and otitis media in children

OBJECTIVE

An alternative option in the prophylaxis and the management of infectious diseases is the use of probiotics, which are known to stabilize gut microbiota and stimulate immune function. Otitis media (OM) is the most common bacterial infection in childhood. The aim of this review is to present the current knowledge of the effects of probiotics on OM.

METHODS

A PUBMED search was made to review the relevant literature, and publications on probiotics and otitis media in children were included. Additional studies were obtained from the references of the selected articles.

RESULTS

Only a few studies using different probiotic strains and study populations have investigated the effects of probiotics on OM. Five studies investigating the effects of oral probiotics, and three studies investigating the effect of probiotic nasal spray treatment were included in this review. Oral probiotics have reduced the incidence of OM in healthy children in one of two studies (days with OM: probiotic 0.5 vs. control 1.0; p=0.003) and in newborns in one of two studies (incidence of OM: probiotic 22%, placebo 50%; p=0.014), but has had no effect on OM in one study in otitis prone children. Nasal spray treatment containing α streptococci has led to clinical improvement in children with recurrent or secretory OM in two of three studies (cured: probiotic 42% vs. placebo 22%, p=0.02; recovery: probiotic 7/19 patients vs. placebo 1/17, p<0.05).

CONCLUSIONS

Although there are some promising results, the lack of confirmative studies makes it difficult to draw any conclusions. More studies are needed to identify the most promising probiotic strains and study populations, and to evaluate the mechanisms behind the possible effects of probiotics on OM.

Modern approaches in probiotics research to control foodborne pathogens

Foodborne illness is a serious public health concern. There are over 200 known microbial, chemical, and physical agents that are known to cause foodborne illness. Efforts are made for improved detection, control and prevention of foodborne pathogen in food, and pathogen associated diseases in the host. Several commonly used approaches to control foodborne pathogens include antibiotics, natural antimicrobials, bacteriophages, bacteriocins, ionizing radiations, and heat. In addition, probiotics offer a potential intervention strategy for the prevention and control of foodborne infections. This review focuses on the use of probiotics and bioengineered probiotics to control foodborne pathogens, their antimicrobial actions, and their delivery strategies. Although probiotics have been demonstrated to be effective in antagonizing foodborne pathogens, challenges exist in the characterization and elucidation of underlying molecular mechanisms of action and in the development of potential delivery strategies that could maintain the viability and functionality of the probiotic in the target organ.

Preliminary safety evaluation of a new Bacteroides xylanisolvens isolate

Besides conferring some health benefit to the host, a bacterial strain must present an unambiguous safety status to be considered a probiotic. We here present the preliminary safety evaluation of a new Bacteroides xylanisolvens strain (DSM 23964) isolated from human feces. First results suggest that it may be able to provide probiotic health benefits. Its identity was confirmed by biochemical analysis, by sequencing of its 16S rRNA genes, and by DNA-DNA hybridization. Virulence determinants known to occur in the genus Bacteroides, such the bft enterotoxin and other enzymatic activities involved in the degradation of the extracellular matrix and the capsular polysaccharide PS A, were absent in this strain. The investigation of the antibiotic susceptibility indicated that strain DSM 23964 was sensitive to metronidazole, meropenem agents, and clindamycin. Resistance to penicillin and ampicillin was identified to be conferred by the β-lactamase cepA gene and could therefore be restored by adding β-lactamase inhibitors. The localization of the cepA gene in the genome of strain DSM 23964 and the absence of detectable plasmids further suggest that a transfer of β-lactamase activity or the acquisition of other antibiotic resistances are highly improbable. Taken together, the presented data indicate that the strain B. xylanisolvens DSM 23964 has no virulence potential. Since it also resists the action of gastric enzymes and low-pH conditions, this strain is an interesting candidate for further investigation of its safety and potential health-promoting properties.

Safety assessment of the commensal strain Bacteroides xylanisolvens DSM 23964

We recently isolated and characterized the new strain Bacteroides xylanisolvens DSM 23964 and presented it as potential candidate for the first natural probiotic strain of the genus Bacteroides. In order to evaluate the safety of this strain for use in food, the following standard toxicity assays were conducted with this strain in both viable and pasteurized form: in vitro bacterial reverse mutation assay, in vitro chromosomal aberration assay, and 90day subchronic repeated oral toxicity studies in mice. No mutagenic, clastogenic, or toxic effects were detected even at extremely high doses. In addition, no clinical, hematological, ophthalmological, or histopathological abnormality could be observed after necropsy at any of the doses tested. Hence, the NOAEL could be estimated to be greater than 2.3×10(11) CFUs, and 2.3×10(14) for pasteurized bacteria calculated as equivalent for an average 70kg human being. In addition, the absence of any in vivo pathogenic properties of viable B. xylanisolvens DSM 23964 cells was confirmed by means of an intraperitoneal abscess formation model in mice which also demonstrated that the bacteria are easily eradicated by the host's immune system. The obtained results support the assumed safety of B. xylanisolvens DSM 23964 for use in food.

Gut microbiota and the role of probiotics in therapy

Thanks to rapid progress in the development and application of molecular techniques to the assessment of the human gut microbiome, the true nature, diversity and metabolic potential of this 'hidden organ' are being revealed. Simultaneously, the complex physiological, immunological and metabolic interactions between host and microbiome are being untangled. By contrast, the probiotic concept has been with us for decades and, while supported more by fad and folklore in the past, is now gaining support, not only from experimental work in animal models, but also by well-designed studies in human diseases, most notably infectious diarrheas, inflammatory bowel disease and the irritable bowel syndrome.

Evidence-based guidelines for use of probiotics in preterm neonates

BACKGROUND

Current evidence indicates that probiotic supplementation significantly reduces all-cause mortality and definite necrotising enterocolitis without significant adverse effects in preterm neonates. As the debate about the pros and cons of routine probiotic supplementation continues, many institutions are satisfied with the current evidence and wish to use probiotics routinely. Because of the lack of detail on many practical aspects of probiotic supplementation, clinician-friendly guidelines are urgently needed to optimise use of probiotics in preterm neonates.

AIM

To develop evidence-based guidelines for probiotic supplementation in preterm neonates.

METHODS

To develop core guidelines on use of probiotics, including strain selection, dose and duration of supplementation, we primarily used the data from our recent updated systematic review of randomised controlled trials. For equally important issues including strain identification, monitoring for adverse effects, product format, storage and transport, and regulatory hurdles, a comprehensive literature search, covering the period 1966-2010 without restriction on the study design, was conducted, using the databases PubMed and EMBASE, and the proceedings of scientific conferences; these data were used in our updated systematic review.

RESULTS

In this review, we present guidelines, including level of evidence, for the practical aspects (for example, strain selection, dose, duration, clinical and laboratory surveillance) of probiotic supplementation, and for dealing with non-clinical but important issues (for example, regulatory requirements, product format). Evidence was inadequate in some areas, and these should be a target for further research.

CONCLUSION

We hope that these evidence-based guidelines will help to optimise the use of probiotics in preterm neonates. Continued research is essential to provide answers to the current gaps in knowledge about probiotics.

State of the art in benefit-risk analysis: food microbiology

Over the past years benefit-risk analysis (BRA) in relation to foods and food ingredients has gained much attention; in Europe and worldwide. BRA relating to food microbiology is however a relatively new field of research. Microbiological risk assessment is well defined but assessment of microbial benefits and the weighing of benefits and risk has not been systematically addressed. In this paper the state of the art in benefit-risk analysis in food microbiology is presented, with a brief overview of microbiological food safety practices. The quality and safety of foods is commonly best preserved by delaying the growth of spoilage bacteria and contamination by bacterial pathogens. However, microorganisms in food can be both harmful and beneficial. Many microorganisms are integral to various food production processes e.g. the production of beer, wine and various dairy products. Moreover, the use of some microorganisms in the production of fermented foods are often claimed to have beneficial effects on food nutrition and consumer health. Furthermore, food safety interventions leading to reduced public exposure to foodborne pathogens can be regarded as benefits. The BRA approach integrates an independent assessment of both risks and benefits and weighs the two using a common currency. Recently, a number of initiatives have been launched in the field of food and nutrition to address the formulation of the benefit-risk assessment approach. BRA has recently been advocated by EFSA for the public health management of food and food ingredients; as beneficial and adverse chemicals can often be found within the same foods and even the same ingredients. These recent developments in the scoping of BRA could be very relevant for food microbiological issues. BRA could become a valuable methodology to support evaluations and decision making regarding microbiological food safety and public health, supplementing other presently available policy making and administrative tools for microbiological food safety management.

How beneficial is the use of probiotic supplements for the aging gut?

The specific health benefits of probiotic supplementation in aging populations remain relatively undefined. Although some probiotic research performed to date has focused on specific populations – particular disease groups or those in dynamic life stages such as the very young and older adults – dedicated studies of older subjects with a typical range of age-related conditions are few. Published studies also feature a narrow range of probiotic strains. Exploitation of strain specificity to modulate the composition and function of the microbiota is crucial to maximize the potential benefit of probiotics. A combination of prebiotic (dietary) and probiotic agents may prove most effective in targeted modulation of the microbiota. The efficacy of specific probiotic strains in modulating the microbiota of older populations is worth pursuing, although the role of antibiotics and polypharmacy (use of multiple medications) in influencing the potential benefits of probiotic intervention requires more dedicated study.

Pulse probiotic administration induces repeated small intestinal Muc3 expression in rats

Upon ingestion, probiotics may act to protect the host through a number of protective mechanisms including modulation of genes involved in intestinal innate mucosal defense such as epithelial cell-derived mucin glycoproteins and inhibitor of apoptosis proteins. To determine the specificity of effect and sustainability of response in vivo, Lactobacillus plantarum 299v (Lp299v), Lactobacillus rhamnosus R0011 (LrR0011), and Bifidobacterium bifidum R0071 (BbR0071) were added repeatedly or intermittently to the drinking water of Sprague-Dawley rats. After killing the rats via CO2 suffocation, Muc2, Muc3, neuronal apoptosis inhibitor protein (NAIP), human inhibitor of apoptosis protein 1/cellular inhibitor of apoptosis 2 (HIAP1/cIAP2), and human inhibitor of apoptosis protein 2/cellular inhibitor of apoptosis 1 (HIAP2/cIAP1) mRNA and protein levels were analyzed via RT-PCR and immunohistochemistry. Live Lp299v, BbR0071, and LrR0011 increased Muc3 protein and mRNA expression in jejunum and ileum. Heat-killed and a nonadherent derivative of Lp299v failed to induce Muc3 expression. Lp299v did induce expression of HIAP2/cIAP1 and NAIP expression. Muc3 mucin expression was elevated for 5 d after oral administration of Lp299v; however, this effect was not sustained despite ongoing daily ingestion of a probiotic. Intermittent pulse ingestion of probiotics, however, was found to repeatedly increase Muc3 expression. We conclude that selected probiotics can induce protective genes of mucosal intestinal epithelial cells, an effect that is reproducible with pulse probiotic administration.

Therapies aimed at the gut microbiota and inflammation: antibiotics, prebiotics, probiotics, synbiotics, anti-inflammatory therapies

Several recent observations have raised the possibility that disturbances in the gut microbiota and/or a low-grade inflammatory state may contribute to symptomatology and the etiology of irritable bowel syndrome (IBS). Consequent on these hypotheses, several therapeutic categories have found their way into the armamentarium of those who care for IBS sufferers. These agents include probiotics, prebiotics, antibiotics, and anti-inflammatory agents.

Probiotics in gastrointestinal disorders

A new era in medical science has dawned with the realization of the critical role of the "forgotten organ," the enteric flora, in health and disease. Central to this beneficial interaction between the flora and humans is the manner in which the bacteria contained within the gut "talk" to the immune system and, in particular, the immune system that is widespread within the gut itself, the gut- (or mucosa-) associated lymphoid tissue (GALT or MALT). Into this landscape comes a new player: the probiotic. While many products have masqueraded as probiotics, only those that truly and reproducibly contain live organisms and have been shown, in high-quality human studies, to confer a health benefit can actually claim this title. Several human disease states have benefited from the use of probiotics, most notably diarrheal illnesses, some inflammatory bowel diseases, and certain infectious disorders. Irritable bowel syndrome can now be added to this list. Although this area holds much promise, more high-quality trials of probiotics in digestive disorders, as well as laboratory investigations of their mechanisms of action, are required.