Effects of Lactobacillus fermentum CECT5716 Lc40 on infant growth and health: a randomised clinical trial in nursing women.

The breast milk microbiota has been described as a source of bacteria for infant gut colonisation. We studied the effect of Lactobacillus fermentum CECT5716 (Lc40) on growth and infection incidence of the infants, when the probiotic is administrated to the mothers. Moreover, whether such effects might depend on the interaction between the mother or infant microbiota and the probiotic administration. A total of 291 mother-infant pairs were studied for 16 weeks in a randomised double-blinded placebo-controlled multicentre trial. The Lc40 group (n=139) received 1 capsule/day containing 3×109 cfu Lc40; the control group (n=152) received 1 placebo (maltodextrin) capsule/day. A positive and significant correlation of the Staphylococcus load between breast milk and infant faeces was only observed in control group. Additionally, the weight z-score of the infants whose mothers had higher values of Lactobacillus in their breast milk were significantly higher for the Lc40 group. We observed a significant lower incidence of conjunctivitis in the infants whose mothers received Lc40. A higher load of Staphylococcus in infant faeces significantly increased the risk of respiratory infections. Such incidence, under an absent or low Staphylococcus load in the faeces, was significantly 36 times higher in the infants in the control group than in the infants in the Lc40 group. However, the protective effect of Lc40 was gradually reduced as the Staphylococcus load of the milk increased. The administration of Lc40 to nursing women might influence infant growth and health but it seems to depend on its interactions with mother or infant microbiota. Registered in the US Library of Medicine (www.clinicaltrials.gov): NCT02203877.

Safety assessment of the human milk-isolated probiotic Lactobacillus salivarius CECT5713.

The potential probiotic bacteria Lactobacillus salivarius CECT5713 has recently been isolated from human milk and characterized. The objective of the present study was to evaluate the oral toxicity of this potential probiotic bacteria in mice. With this aim, 50 Balb/C mice were divided in 5 groups (n = 10). Three of these groups were treated orally with different doses of L. salivarius CECT5713: 5 x 10(8), 2 x 10(9), or 10(10) cfu/mouse per d for 28 d. One additional group was administered the vehicle alone and was used as a control. The last group were injected intraperitoneally with 10(8) cfu/mouse in a single dose and killed 2 (n = 5) and 5 (n = 5) d after intraperitoneal injection. Food intake, body weight, bacterial translocation, serum alpha-amyloid protein, and different biochemical parameters were analyzed. Oral administration of L. salivarius CECT5713 to mice had no adverse effects on mouse body weight or food intake. No bacteremia was shown and there was no treatment-associated bacterial translocation to the liver or spleen. Intraperitoneal administration caused a significant bacterial translocation to the liver and spleen, but not to the blood. However, this translocation was not related to illness or death at either d 2 or d 5, although an increase in plasma serum alpha-amyloid protein was observed at d 2. These results suggest that the strain L. salivarius CECT5713 is nonpathogenic for mice, even in doses 10,000 times higher (expressed per kilograms of body weight) than those normally consumed by humans. Thus, this strain is likely to be safe for human consumption.

Two Lactobacillus strains, isolated from breast milk, differently modulate the immune response.

AIMS: The ability of two different Lactobacillus strains (Lactobacillus salivarius CECT5713 and Lactobacillus fermentum CECT5716), isolated from human breast milk, to modulate the immune response was examined. METHODS AND RESULTS: In rodent bone-marrow-derived macrophages (BMDM), the presence of Lact. fermentum CECT5716 induced pro-inflammatory cytokines, in contrast to the activation of IL-10 induced by Lact. salivarius CECT5713. Although both strains reduced the lipopolysaccharide (LPS)-induced inflammatory response in BMDM, the effect of Lact. salivarius CECT5713 was more efficient, probably because of the production of higher amounts of IL-10 cytokine. In vivo assays in mice showed similar results; the consumption of Lact. fermentum CECT5716 enhanced the production of Th1 cytokines by spleen cells and increased the IgA concentration in faeces. However, the consumption of Lact. salivarius CECT5713 induced IL-10 production by spleen cells. CONCLUSION: Therefore, in general, the effect of Lact. fermentum CECT5716 is immunostimulatory in contrast to the anti-inflammatory effect of Lact. salivarius CECT5713. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study show that two Lactobacillus strains isolated from breast milk can exert different and even opposing effects on immune response demonstrating the specificity of each strain.

Antimicrobial potential of four Lactobacillus strains isolated from breast milk.

AIMS: The antimicrobial potential of four lactobacilli (Lactobacillus salivarius CECT5713, Lactobacillus gasseri CECT5714, L. gasseri CECT5715 and Lactobacillus fermentum CECT5716), isolated from fresh human breast milk, was evaluated in this study and compared with Lactobacillus coryniformis CECT5711, a reuterin-producing strain isolated from an artisan goat's cheese. METHODS AND RESULTS: Agar diffusion tests, competitive adhesion assays and mucin expression assays were carried out in order to value the antibacterial properties of the lactobacilli strains. The antibacterial capability of the strains was tested in vivo by using a murine infection model with Salmonella choleraesuis. The results revealed that all the strains studied, displayed antibacterial properties against pathogenic bacteria. However, the antibacterial potential varied among the lactobacilli tested and, in fact, L. salivarius CECT5713 showed not only the best in vitro antibacterial activity, but also the highest protective effect against a Salmonella strain in the murine infection model. CONCLUSION: The four breast-milk lactobacilli, and particularly L. salivarius CECT5713, possess potent antibacterial activities that result in a higher protection against S. choleraesuis CECT4155 in a mouse infection model. SIGNIFICANCE AND IMPACT OF THE STUDY: These results suggest that lactobacilli from breast milk could contribute to an anti-infective protection in neonates and would be excellent candidates for the development of infant probiotic products.