Adhesion of Lactobacillus reuteri strain Lr1 to equine epithelial cells and competitive exclusion of Clostridium difficile from the gastro-intestinal tract of horses 

Summary: One of the key properties of a probiotic is the ability to compete with pathogens for binding to epithelial cells or mucus.

Lactobacillus reuteri, infant allergy prevention and childhood immune maturation

Summary:The increasing allergy prevalence in affluent countries may be caused by reduced microbial stimulation, resulting in an abnormal postnatal immune maturation.In human allergy intervention studies, probiotic supplementation to the mother during pregnancy, as well as to her baby postnatally, may be important for preventive effects. Also, prenatal environmental exposures may alter gene expression via epigenetic mechanisms, aiming to induce physiological adaptations to the anticipated postnatal environment. The maternal microbial environment during pregnancy may program the immune development of the child.

Feline intestinal microbiota

Summary: The close relationship between gastrointestinal (GI) microbiota and its host has an impact on the health status of an animal that reaches beyond the GI tract. A balanced microbiome stimulates the immune system, aids in the competitive exclusion of transient pathogens and provides nutritional benefits to the host.  Several nutritional studies have demonstrated that the feline microbiota can be modulated by the amount of soluble fibers (i.e., prebiotics) and macronutrients (i.e., protein content) in the diet.

Lactobacillus reuteri as a therapeutic agent in acute diarrhea in young children

Summary: Certain strains of lactobacilli may promote recovery from acute diarrhea. Lactobacillus reuteri is of human origin and is a natural colonizer of gastrointestinal tract. In this trial, exogenously administered L. reuteri was studied as a therapeutic agent in acute diarrhea.

Lactobacillus reuteri derived from horse alleviates escherichia coli induced diarrhea by modulating gut microbiota

Summary: Supplementation of Lactobacillus reuteri alleviate diarrhea induced by E. coli infection and restore the decline of tight junction genes, such as Claudin-1 and ZO-1. Additionally, Lactobacillus reuteri supplementation can restore the expression of inflammatory factors (IL-6, IL-10, TNF-α, and IFN-γ) and reduce colon inflammatory damage.

Assessment of clinical and microbiota responses to fecal microbial transplantation in adult horses with diarrhea

Background and aims: Fecal microbial transplantation (FMT) is empirically implemented in horses with colitis to facilitate resolution of diarrhea. The purpose of this study was to assess FMT as a clinical treatment and modulator of fecal microbiota in hospitalized horses with colitis.

Salmonella Antimicrobial Activity of Selected Strains of Enterolactobacillus
Species Isolated from the Gastrointestinal Tract of the Horse

The gastric mucosa and the mucosa of the right and left dorsal colon were biopsied in each of the 15 horses, and a total of 45 samples were collected. Mucosal samples were cultured using a Lactobacillus enrichment broth. While numerous Lactobacillus strains were identified, Lactobacillus reuteri was the most common organism identified. Sixteen strains of Lactobacillus reuteri were selected for antimicrobial testing. Salmonella antimicrobial activity was identified in six out of 16 strains tested. Organisms with Salmonella antimicrobial activity were cultured from the stratified squamous epithelium of the stomach and the mucosa of the right and left dorsal colon.

Isolation and characterization of Lactobacillus species having potential for use as probiotic cultures for dogs

The need to control pathogenic microorganisms in the intestinal tract of dogs is a growing concern. There is interest in using probiotics such as species of Lactobacillus to help control canine intestinal infections. For successful use as a probiotic, the bacterial species should be of canine intestinal origin since these species exhibit host specificity. Serial dilutions of freshly voided dog feces were plated on Lactobacillus selection (LBS) agar to isolate the cultures. Isolates were identified based on Gram stain, catalase test, and fermentation patterns using API 50 CH kits. All potential isolates were compared for bile resistance based on relative ability to grow in broth containing 0.3% Oxgall, the ability to inhibit Salmonella Typhimurium in associative broth cultures, and the production of reuterin. Of the lactobacilli isolated, Lactobacillus reuteri was the dominant species. However, some cultures of L. acidophilus also were isolated. We found variations among the isolates of L. reuteri and L. acidophilus with respect to bile tolerance. In general, isolates of L. reuteri appeared to be more bile resistant than were isolates of L. acidophilus. There were also variations in the ability to inhibit growth of S. Typhimurium. Some isolates of L. reuteri produced reuterin while others did not.

Modulation of anti-pathogenic activity in canine-derived Lactobacillus species by carbohydrate growth substrate

Aims: To investigate the effect of various carbon sources on the production of extracellular antagonistic compounds against two Escherichia coli strains and Salmonella enterica serotype Typhimurium by three canine-derived lactobacilli strains.

Methods and materials: Cell-free preparations, pH neutralized, were used in antibiotic disc experiments as an initial screening. The bacteria/carbohydrate combinations that showed inhibition of the growth of those pathogens, were further investigated in batch co-culture experiments. The cell-free supernatants of the cultures, that decreased the population number of the pathogens in the co-culture experiments to log CFU ml-1 <or= 4, were tested for inhibition of the pathogens in pure cultures at neutral and acidic pH.

Conclusions: The results showed that the substrate seems to affect the production of antimicrobial compounds and this effect could not just be ascribed to the ability of the bacteria to grow in the various carbon sources. L. mucosae, L. acidophilus and L. reuteri, when grown in sugar mixtures consisting of alpha-glucosides (Degree of Polymerization (DP) 1-4) could produce antimicrobial compounds active against all three pathogens in vitro. This effect could not be attributed to a single ingredient of those sugar mixtures and was synergistic. This inhibition had a dose-response characteristic and was more active at acidic pH.

Significance and impact of the study: Knowledge of the effect that the carbon source has on the production of antimicrobial compounds by gut-associated lactobacilli allows the rational design of prebiotic/probiotic combinations to combat gastrointestinal pathogens.

Lactobacillus reuteri good for health, Swedish study finds

There is a great deal of interest in the impact of lactic acid bacteria on our health. Now a new study from the Faculty of Health and Society, Malmö University, in Sweden, shows that the occurrence of Lactobacillus reuteri in the body promotes health.

Evaluation of a Host-Specific Lactobacillus Probiotic in Neonatal Foals

A randomized, placebo-controlled, double-blind clinical trial was conducted on 54 neonatal foals to examine the effect and safety of a host-specific probiotic preparation. The probiotic contained a mixture of five strains of lactobacilli isolated from healthy horses (Lactobacillus salivarius YIT 0479, L. reuteri YIT 0480, L. crispatus YIT 0481, L. johnsonii YIT 0482 and L. equi YIT 0483), and was administered daily to 27 of the foals (1 to 7 days of age). A control group of 27 foals was given a placebo. Comparisons between the two groups were made for increase in body weight, the frequency of diarrhea, the composition of intestinal microflora, and the levels of short-chain fatty acids in the feces. Protobiotic treatment caused no clinical side effects. The probiotic lead to a significant increase (P < 0.01) in body weight in 1-month-old foals and a significantly lower incidence (P < 0.05) of diarrhea at 3 weeks of age. No significant differences were found between the fecal bacterial populations in the two groups, although a trend toward earlier colonization of Lactobacillus in the treated foals was seen. Our findings suggest that the administration of an equine-specific Lactobacillus probiotic to neonatal foals enhances growth and decreases the incidence of diarrhea.

Identification of Equine Cecal Bacteria Producing Amines in an In Vitro Model of Carbohydrate Overload

Acute laminitis has been associated with the overgrowth of gram-positive bacteria within the equine hindgut, causing the release of factor(s) leading to ischemia-reperfusion of the digits. The products of fermentation which trigger acute laminitis are, as yet, unknown; however, vasoactive amines are possible candidates. The objectives of this study were to use an in vitro model of carbohydrate overload to study the change in populations of cecal streptococci and lactobacilli and to establish whether certain species of these bacteria were capable of producing vasoactive amines from amino acids. Cecal contents from 10 horses were divided into aliquots and incubated anaerobically with either corn starch or inulin (fructan; both at 1 g/100 ml). Samples were taken at 6-h intervals over a 24-h period for enumeration of streptococci, lactobacilli, and gram-negative anaerobes by a dilution method onto standard selective growth media. The effects of the antibiotic virginiamycin (1 mg/100 ml) and calcium hydrogen phosphate (CaHPO4; 0.3 g/100 ml) were also examined. Fermentation of excess carbohydrate was associated with increases in numbers of streptococci and lactobacilli (2- to 3.5-log unit increases; inhibited by virginiamycin) but numbers of gram-negative anaerobes were not significantly affected. A screening agar technique followed by 16S rRNA gene sequence analysis enabled the identification of 26 different bacterial strains capable of producing one or more vasoactive amines. These included members of the species Streptococcus bovis and five different Lactobacillus spp. These data suggest that certain bacteria, whose overgrowth is associated with carbohydrate fermentation, are capable of producing vasoactive amines which may play a role in the pathogenesis of acute laminitis.

Efficacy of Saccharomyces boulardii for treatment of horses with acute enterocolitis

Objective—To evaluate the viability of Saccharomyces boulardii after PO administration in clinically normal horses and its efficacy as a treatment for horses with acute enterocolitis.

Design—Prospective study.

Animals—5 clinically normal horses and 14 horses with acute enterocolitis.

Procedure—Feces were collected from 5 clinically normal horses and submitted for microbial culture for 2 days prior to administration of a lyophilized form of S boulardii (25 or 50 g, PO, q 12 h) for 10 days. Feces were collected for microbial culture 5 and 10 days after treament initiation and 10 days after treatment was discontinued. Fourteen horses with acute enterocolitis were randomly allocated to receive a placebo or S boulardii (25 g), PO, every 12 hours for 14 days.

ResultsS boulardii was not detected in feces of clinically normal horses. After administration, yeast survived within the gastroinestinal tract but did not permanently colonize it. In horses with acute enterocolitis, the severity and duration of gastrointestinal tract disease during hospitalization were significantly decreased in horses receiving S boulardii, compared with horses receiving the placebo.

Conclusions and Clinical Relevance—Administration of S boulardii may help decrease the severity and duration of clinical signs in horses with acute enterocolitis. (J Am Vet Med Assoc 2005;227:954–959)

Lactobacillus reuteri-induced regulatory T cells protect against an allergic airway response in mice

Rationale: We have previously demonstrated that oral treatment with live Lactobacillus reuteri can attenuate major characteristics of the asthmatic response in a mouse model of allergic airway inflammation. However, the mechanisms underlying these effects remain to be determined.

Objectives: We tested the hypothesis that regulatory T cells play a major role in mediating L. reuteri-induced attenuation of the allergic airway response.

Methods: BALB/c mice were treated daily with L. reuteri by gavage. Flourescent-activated cell sorter analysis was used to determine CD4(+)CD25(+)Foxp3(+)T cell populations in spleens following treatment with L. reuteri or vehicle control. Cell proliferation assays were performed on immunomagnetic bead separated CD4(+)CD25(+) and CD4(+)CD25(-) T cells. CD4(+)CD25(+) T cells isolated from, ovalbumin naive, L. reuteri treated mice were transferred into ovalbumin-sensitized mice. Following antigen challenge the airway responsiveness, inflammatory cell influx and cytokine levels in bronchoalveolar lavage fluid of recipient mice were assessed.

Measurements and main results: Following 9 days of oral L. reuteri treatment, the percentage and total number of CD4(+)CD25(+)Foxp3(+)T cells in spleens significantly increased. CD4(+)CD25(+) cells isolated from L. reuteri-fed animals also had greater capacity to suppress T-effector cell proliferation. Adoptive transfer of CD4(+)CD25(+) T cells from L. reuteri-treated mice to ovalbumin-sensitized animals attenuated airway hyper-responsiveness and inflammation in response to subsequent antigen challenge.

Conclusions: These results strongly support a role for nonantigen-specific CD4(+)CD25(+)Foxp3(+) regulatory T cells in attenuating the allergic airway response following oral treatment with L. reuteri. This potent immuno-regulatory action may have therapeutic potential in controlling the Th2 bias observed in atopic individuals.

Impact of Lactobacillus reuteri colonization on gut microbiota, inflammation, and crying time in infant colic

Infant colic is a distressing condition of unknown etiology. An aberrant gastrointestinal microbiota has been associated, and Lactobacillus reuteri supplementation has been shown to reduce crying and/or fussing time (‘crying time’) in some infants with colic. The relationship between L. reuteri gut colonization and crying time has not been examined. We investigated the relationship between L. reuteri colonization and fecal microbiota (microbial diversity and Escherichia coli), intestinal inflammation, and crying time in infants with colic, using a subset of 65 infants from the Baby Biotics trial, which randomized healthy term infants aged <13 weeks with infant colic to receive probiotic L. reuteri DSM 17938 (1 × 108 colony forming units) or placebo daily for 28 days. We observed an overall reduction in median crying time, regardless of L. reuteri colonization status (n = 14 colonized). There were no differences in E. coli colonization rates or densities, microbial diversity or intestinal inflammation by L. reuteri colonization status. We found that L. reuteri density positively correlated with crying time, and E. coli density negatively correlated with microbial diversity. As density of L. reuteri was associated with increased crying time, L. reuteri supplementation may not be an appropriate treatment for all infants with colic.

Lactobacillus reuteri DSM 17938 feeding of healthy newborn mice regulates immune responses while modulating gut microbiota and boosting beneficial metabolites

Early administration of Lactobacillus reuteri DSM 17938 (LR) prevents necrotizing enterocolitis and inhibits regulatory T-cell (Treg)-deficiency-associated autoimmunity in mice. In humans, LR reduces crying time in breastfed infants with colic, modifies severity in infants with acute diarrheal illnesses, and improves pain in children with functional bowel disorders. In healthy breastfed newborns with evolving microbial colonization, it is unclear if early administration of LR can modulate gut microbiota and their metabolites in such a way as to promote homeostasis. We gavaged LR (107 colony-forming units/day, daily) to C57BL/6J mice at age of day 8 for 2 wk. Both male and female mice were investigated in these experiments. We found that feeding LR did not affect clinical phenotype or inflammatory biomarkers in plasma and stool, but LR increased the proportion of Foxp3+ regulatory T cells (Tregs) in the intestine. LR also increased bacterial diversity and the relative abundance of p_Firmicutes, f_Lachnospiraceaef_Ruminococcaceae, and genera Clostridium and Candidatus arthromitus, while decreasing the relative abundance of p_Bacteriodetes, f_Bacteroidaceaef_Verrucomicrobiaceae, and genera BacteroidesRuminococcus, Akkermansia, and Sutterella. Finally, LR exerted a major impact on the plasma metabolome, upregulating amino acid metabolites formed via the urea, tricarboxylic acid, and methionine cycles and increasing tryptophan metabolism. In conclusion, early oral administration of LR to healthy breastfed mice led to microbial and metabolic changes which could be beneficial to general health.NEW & NOTEWORTHY Oral administration of Lactobacillus reuteri DSM 17938 (LR) to healthy breastfed mice promotes intestinal immune tolerance and is linked to proliferation of beneficial gut microbiota. LR upregulates plasma metabolites that are involved in the urea cycle, the TCA cycle, methionine methylation, and the polyamine pathway. Herein, we show that LR given to newborn mice specifically increases levels of tryptophan metabolites and the purine nucleoside adenosine that are known to enhance tolerance to inflammatory stimuli.

The Gut: Where Bacteria and Immune System Meet

November 2015—By now, it’s a familiar fact: Humans have more bacterial cells—a lot more—than human cells. Bacteria live on the skin, in the nose and ears, and, most of all, in the gut.

Until recently, if most people thought about those bacteria at all, we tended to think of them as fairly separate from us. They help with digestion, but otherwise they stay on their side of the intestinal lining, and we stay on our side. But, in fact, there is a lot of interaction between the body’s immune system and bacteria in the gut. Researchers at Johns Hopkins are now in the early stages of figuring out how the composition of the gut changes in different diseases, how the body’s immune system interacts with these tiny hitchhikers and particularly how that relationship may function in disease.