Probiotics for the primary and secondary prevention of C. difficile infections: a meta-analysis and systemic review. Antibiotics (Basel). 2015;4:160-178. [PMID: 27025619 PMCID: PMC4790329 DOI: 10.3390/antibiotics4020160]

Primary prevention of Clostridium difficile infections - how difficult can it be?

C. difficile infections (CDI) have been a challenging disease to treat, much less to prevent, for decades. Efforts for primary prevention have mainly focused on improving infection control practices, but CDI outbreaks continue to plague healthcare facilities. Areas covered: A literature search from 1970-December 2016 found 13 facility-level and 2 patient-level strategies that were evidence-based. The aim of this manuscript is to assess the current state of the literature on primary prevention of CDI and offer insights into which strategies may be more effective. Expert commentary: The strongest evidence for primary prevention is based on multi-faceted infection control bundles, while there is promising moderate evidence involving facility-wide use of specific probiotics. Moderate-level evidence was found for patient-level use of specific probiotics and low level evidence for vaccines. Future suggestions include use of consistent outcome metrics, measurements of implementation compliance and program sustainability.

A review of dose-responses of probiotics in human studies

The probiotic definition requires the administration of an 'adequate amount' in order to obtain a health benefit. What that amount should be is not indicated. Here, an overview is given of studies that investigated the dose-response relation of probiotics in human interventions. Studies were divided in; meta-analyses, meta-analyses on specific probiotic strains, and studies testing two or more doses of a probiotic (combination) in the same study. Meta-analyses on the effect of probiotics on antibiotic associated diarrhoea (AAD) suggest a dose-response effect; for Clostridium difficile-associated diarrhoea on the other hand no dose-response was observed. For other end-points; such as necrotising enterocolitis, prevention of atopic dermatitis and slow intestinal transit, no dose-response relation was identified in meta-analyses. For prophylaxis in colorectal cancer and relief of irritable bowel syndrome, no dose-response relation was determined. However, for blood pressure, a meta-analysis observed that higher doses (greater than 10¹¹ cfu) were more effective than lower doses. Meta-analyses of specific strains suggest a break-point for effectiveness of Lactobacillus rhamnosus GG in the treatment of acute gastroenteritis in children; no dose-response was observed for two other probiotics assessed. Studies comparing two or more doses indicate that faecal recovery and risk reduction of AAD follow a positive dose-response relationship. Other end-points such as immune markers, general health, and bowel function did not exhibit clear dose-response relations. For AAD, the findings are very compelling; both meta-analyses and dedicated dose-response studies observe a positive correlation between dose and AAD risk. These findings do not allow for extrapolation, but suggest that studying higher doses for this end-point would be worthwhile. The lack of a clear dose-response for other end-points, does not mean it does not exist; present data does just not allow drawing any conclusions.

Eosinophils, probiotics, and the microbiome

There is currently substantial interest in the therapeutic properties of probiotic microorganisms as recent research suggests that oral administration of specific bacterial strains may reduce inflammation and alter the nature of endogenous microflora in the gastrointestinal tract. Eosinophils are multifunctional tissue leukocytes, prominent among the resident cells of the gastrointestinal mucosa that promote local immunity. Recent studies with genetically altered mice indicate that eosinophils not only participate in maintaining gut homeostasis, but that the absence of eosinophils may have significant impact on the nature of the endogenous gut microflora and responses to gut pathogens, notably Clostridium difficile Furthermore, in human subjects, there is an intriguing relationship between eosinophils, allergic inflammation, and the nature of the lung microflora, notably a distinct association between eosinophil infiltration and detection of bacteria of the phylum Actinobacteria. Among topics for future research, it will be important to determine whether homeostatic mechanisms involve direct interactions between eosinophils and bacteria or whether they involve primarily eosinophil-mediated responses to cytokine signaling in the local microenvironment. Likewise, although is it clear that eosinophils can and do interact with bacteria in vivo, their ability to discern between pathogenic and probiotic species in various settings remains to be explored.

Influence of Saccharomyces boulardii CNCM I-745on the gut-associated immune system

Background

The probiotic Saccharomyces boulardii CNCM I-745 (also known as Saccharomyces cerevisiae HANSEN CBS 5926; in the following S. boulardii) has proven its effectiveness in preventive and therapeutic treatment of many gastrointestinal diseases, especially diseases associated with acute diarrhea. In particular, antibiotic-associated diarrhea, Clostridium difficile-associated diarrhea, traveller’s diarrhea, as well as acute diarrhea due to common viral and bacterial infections in children and adults.

Aim

The aim of this review is to summarize the experimental studies elucidating the molecular and immunological mechanisms by which these clinically proven effects are archived, with an emphasis on the gut-associated immune system. The main focus is laid on anti-inflammatory and immune-modulatory action of S. boulardii involved in bacterial or enterotoxin-mediated diarrhea and inflammation. An attempt is made to differentiate between the effects associated with cellular versus soluble factors and between prophylactic and therapeutic effects.

Methods

A literature search was performed in PubMed/PubMed Central for the effects of S. boulardii on the gut-associated immune system (focus acute diarrhea).

Results and conclusion

S. boulardii exhibits its positive effect by the direct effects on pathogens or their toxins as well as by influencing the host’s infection-induced signaling cascades and its innate and adaptive immune system. The combination of these mechanisms results in a reduction of the pathogens’ ability for adhesion or colonization and an attenuation of the overreacting inflammatory immune response. Thereby, the integrity of the intestinal epithelial cell layer is preserved or restored, and the diarrheic leakage of fluids into the intestinal lumen is attenuated.

An update on probiotics, prebiotics and symbiotics in clinical nutrition

The concept of prebiotics, probiotics, and symbiotics and their use in different situations of daily clinical practice related to clinical nutrition is reviewed, as well as their role in the treatment/prevention of diarrhea (acute, induced by antibiotics, secondary to radiotherapy), inflammatory bowel disease (ulcerative colitis and pouchitis), in colonic health (constipation, irritable bowel), in liver disease (steatosis and minimum encephalopathy), and in intensive care, surgical, and liver transplantation. While their effectiveness for preventing antibiotic-induced diarrhea and pouchitis in ulcerative colitis appears to be shown, additional studies are needed to establish recommendations in most clinical settings. The risk of infection associated to use of probiotics is relatively low; however, there are selected groups of patients in whom they should be used with caution (as jejunum infusion).

Probiotics in Human Immunodeficiency Virus Infection: A Systematic Review and Evidence Synthesis of Benefits and Risks

The risk of sepsis is low. The best probiotic to optimize outcomes has not yet been identified. Potential benefit for CD4 count, recurrence or management of bacterial vaginosis and diarrhea. Uncertain effect on translocation, BV treatment.

People living with human immunodeficiency virus frequently use dietary supplements, including probiotics, but concern exists about ingesting live organisms. We performed a systematic review of the benefits of probiotics and a meta-analysis of sepsis risk. We undertook a protocol-driven, comprehensive review to identify all relevant studies, assess their quality, and summarize the evidence. Of 2068 references, 27 were analyzed. The data suggest possible benefits for CD4 count, recurrence or management of bacterial vaginosis, and diarrhea management. We examined randomized, controlled studies explicitly assessing sepsis in any patient population, and we found zero cases of supplement-associated bacteremia or fungemia in 39 randomized controlled trials comprising 9402 subjects. The estimated number needed to harm is 7369 in Bayesian approach (95% credible interval: 1689, ∞), which should reassure clinicians. No or mild adverse effects were reported. Longer duration studies investigating different individual and mixed strains for plausible indications are needed to establish best practices.

Antimicrobial effects of Lactobacillus plantarum and Lactobacillus acidophilus against multidrug-resistant enteroaggregative Escherichia coli

The in vitro and in vivo antimicrobial effects of Lactobacillus plantarum and Lactobacillus acidophilus were evaluated individually and synergistically against multidrug-resistant enteroaggregative Escherichia coli (MDR-EAEC). In vitro evaluation of each probiotic strain when co-cultured with MDR-EAEC isolates revealed a reduction in MDR-EAEC counts (eosin-methylene blue agar) in a dose- and time-dependent manner: probiotics at a dose rate of 10(10) CFU inhibited MDR-EAEC isolates at 72 h post-inoculation (PI), whereas at lower concentrations (10(8) and 10(9) CFU) MDR-EAEC isolates were inhibited at 96 h PI. The synergistic antimicrobial effect of both probiotic strains (each at 10(10) CFU) was highly significant (P < 0.01) and inhibited the growth of MDR-EAEC isolates at 24 h PI. For in vivo evaluation, weaned mice were fed orally with 10(7) CFU of MDR-EAEC. At Day 3 post-infection, treated mice were fed orally with the probiotic strains (each at 10(10) CFU). Compared with the control, post-treatment a significant (P < 0.01) reduction in MDR-EAEC counts was observed in faeces by Day 2 and in intestinal tissues of treated mice by Days 3 and 4 as evidenced by plate count (mean 2.71 log and 2.27 log, respectively) and real-time PCR (mean 1.62 log and 1.57 log, respectively) methods. Histopathologically, comparatively mild changes were observed in the ileum and colon from Days 3 to 5 post-treatment with probiotics; however, from Day 6 the changes were regenerative or normal. These observations suggest that these probiotic strains can serve as alternative therapeutics against MDR-EAEC-associated infections in humans and animals.

Epidemiology, Diagnosis, and Management of Clostridium difficile Infection in Patients with Inflammatory Bowel Disease

Clostridium difficile infection (CDI) is a major source of morbidity and mortality for the U.S. health care system and frequently complicates the course of inflammatory bowel disease (IBD). Patients with IBD are more likely to be colonized with C. difficile and develop active infection than the general population. They are also more likely to have severe CDI and develop subsequent complications such as IBD flare, colectomy, or death. Even after successful initial treatment and recovery, recurrent CDI is common. Management of CDI in IBD is fraught with diagnostic and therapeutic challenges because the clinical presentations of CDI and IBD flare have considerable overlap. Fecal microbiota transplantation can be successful in curing recurrent CDI when other treatments have failed, but may also trigger IBD flare and this warrants caution. New experimental treatments including vaccines, monoclonal antibodies, and nontoxigenic strains of C. difficile offer promise but are not yet available for clinicians. A better understanding of the complex relationship between the gut microbiota, CDI, and IBD is needed.

Comparison of pediatric and adult antibiotic-associated diarrhea and Clostridium difficile infections

Antibiotic-associated diarrhea (AAD) and Clostridum difficile infections (CDI) have been well studied for adult cases, but not as well in the pediatric population. Whether the disease process or response to treatments differs between pediatric and adult patients is an important clinical concern when following global guidelines based largely on adult patients. A systematic review of the literature using databases PubMed (June 3, 1978-2015) was conducted to compare AAD and CDI in pediatric and adult populations and determine significant differences and similarities that might impact clinical decisions. In general, pediatric AAD and CDI have a more rapid onset of symptoms, a shorter duration of disease and fewer CDI complications (required surgeries and extended hospitalizations) than in adults. Children experience more community-associated CDI and are associated with smaller outbreaks than adult cases of CDI. The ribotype NAP1/027/BI is more common in adults than children. Children and adults share some similar risk factors, but adults have more complex risk factor profiles associated with more co-morbidities, types of disruptive factors and a wider range of exposures to C. difficile in the healthcare environment. The treatment of pediatric and adult AAD is similar (discontinuing or switching the inciting antibiotic), but other treatment strategies for AAD have not been established. Pediatric CDI responds better to metronidazole, while adult CDI responds better to vancomycin. Recurrent CDI is not commonly reported for children. Prevention for both pediatric and adult AAD and CDI relies upon integrated infection control programs, antibiotic stewardship and may include the use of adjunctive probiotics. Clinical presentation of pediatric AAD and CDI are different than adult AAD and CDI symptoms. These differences should be taken into account when rating severity of disease and prescribing antibiotics.

On Lactococcus lactis UL719 competitivity and nisin (Nisaplin(®)) capacity to inhibit Clostridium difficile in a model of human colon

Clostridium difficile is the most frequently identified enteric pathogen in patients with nosocomially acquired, antibiotic-associated diarrhea and pseudomembranous colitis. Although metronidazole and vancomycin were effective, an increasing number of treatment failures and recurrence of C. difficile infection are being reported. Use of probiotics, particularly metabolically active lactic acid bacteria, was recently proposed as an alternative for the medical community. The aim of this study was to assess a probiotic candidate, nisin Z-producer Lactococcus lactis UL719, competitivity and nisin (Nisaplin^®) capacity to inhibit C. difficile in a model of human colon. Bacterial populations was enumerated by qPCR coupled to PMA treatment. L. lactis UL719 was able to survive and proliferate under simulated human colon, did not alter microbiota composition, but failed to inhibit C. difficile. While a single dose of 19 μmol/L (5× the MIC) was not sufficient to inhibit C. difficile, nisin at 76 μmol/L (20×the MIC) was effective at killing the pathogen. Nisin (at 76 μmol/L) caused some temporary changes in the microbiota with Gram-positive bacteria being the mostly affected. These results highlight the capacity of L. lactis UL719 to survive under simulated human colon and the efficacy of nisin as an alternative in the treatment of C. difficile infections.

The Antimicrobial Stewardship Approach to Combating Clostridium Difficile

Clostridium difficile remains a major public health threat and continues to contribute to excess morbidity, mortality and healthcare costs. Antimicrobial stewardship programs have demonstrated success in combating C. difficile, primarily through antibiotic restrictive strategies. As the incidence and prevalence of C. difficile associate disease continues to increase both in the hospital and community setting, additional stewardship approaches are needed. This manuscript reviews stewardship interventions that have been successful against C. difficile associated disease and proposes future tactics that antimicrobial stewardship programs may employ to develop a more global approach to combat this difficult pathogen.