Probiotic potential of Lactiplantibacillus plantarum strains against Enterococcus faecalis infection in different experimental models.

VERA, M.D.; BLANCO, H.; ARCE, L.P.; RAYA-TONETTI, M.F.; MÜLLER, M.; ORTIZ MOYANO, R.; D'ALMEIDA, R.E.; KITAZAWA, H.; VILLENA, J.; VIZOSO PINTO, M.G.

Congreso; LVII Reunion Anual de la Sociedad Argentina de Investigaciones Biológicas; 2022

The increase in multiresistant bacteria due to the misuse of antibiotics is a growing threat to healthworldwide. Enterococcus faecalis belongs to a group of high priority bacteria resistant to antibiotics asdefined by the World Health Organization. This pathogen has little pathogenic potential in the normalhost, but in the elderly and immunocompromised patients it causes opportunistic infections. Because oftheir increasing frequency and the challenging treatment, there is a need for alternative strategies tocontrol it. The aim of this work was to study the ability of L. plantarum MPL16 and CRL1506 strains to controlE. faecalis in vivo. First, we tested the effect of the feeding of Caenorhabditis elegans with LAB on itslongevity. Usually, when nematodes are fed with E. coli OP50 they live 21-25 days but when they receivedL. plantarum MPL16 or CRL1506, their lifespan increased ~20%. When nematodes were fed with E. faecalis,they suffered intestinal distention and their progeny was affected: most of the eggs did not hatch andthe larvae did not develop normally. Further, the survival decreased [lethality of 50% (L50) = 7 days]. Whenthey received the pre-treatment with the CRL1506 and MPL16, the nematodes reached the L50 24 h and48 h later, respectively, than the infection control. Further, 1 log reduction in enterococci CFU/mL of MPL16-treated nematodes was observed. The strain also restored the reproductive capacity lost by enterococcalinfection. In contrast, L. plantarum CRL1506 did not reduce the bacterial load nor restored fertility. Inaddition, the effect of LAB on resistance to E. faecalis infection in mice immunosuppressed by malnutritionwas studied. BALB/c malnourished mice were on a hypoprotein diet for 21 days, then, they were renourished for 7 days with a conventional balanced diet alone or supplemented with LABs. Afterrenourishment, they were challenged with the E. faecalis 102. The infection was evaluated 48 h postinfection, by counting the CFUs in the intestinal lavage, feces, liver, spleen, and blood. Thesupplementation with LAB to the conventional diet increased resistance against infection by E. faecalis102, which was confirmed by a significant decrease in the CFU counts in the tissue samples. In conclusion,the MPL16 and CRL1506 strains have probiotic potential to prevent or improve E. faecalis infections in botha vertebrate and an invertebrate model. Since the probiotic effect was only observed in vivo, we postulatethat it may be related to the modulation of innate immunity and/or competition for nutrients andadhesion sites, but not to a direct antimicrobial action of the LAB. These strains have a great potential tobe used for prevention of E. faecalis infections in susceptible hosts.