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

VERA DANIELA; BLANCO HECTOR; ARCE LORENA; RAYA-TONETTI MARIA FERNANDA; MULLER MELISA; ORTIZ MOYANO RAMIRO; D'ALMEIDA ROMINA ELISA; KITAZAWA, HARUKI; VILLENA JULIO; VIZOSO PINTO MARIA GUADALUPE

Mendoza

Congreso; Simposio de Investigadores Jóvenes del Congreso SAIB 2022; 2022

The increase in multiresistant bacteria due to the misuse of antibiotics is a growing threat to health worldwide. Enterococcusfaecalis belongs to a group of high priority bacteria resistant to antibiotics as defined by the World Health Organization. Thispathogen has little pathogenic potential in the normal host, but in the elderly and immunocompromised patients it causesopportunistic infections. Because of their increasing frequency and the challenging treatment, there is a need for alternativestrategies to control 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 its longevity. Usually,when nematodes are fed with E. coli OP50 they live 21-25 days but when they received L. plantarum MPL16 or CRL1506,their lifespan increased ~20%. When nematodes were fed with E. faecalis, they suffered intestinal distention and their progenywas affected: most of the eggs did not hatch and the larvae did not develop normally. Further, the survival decreased [lethalityof 50% (L50) = 7 days]. When they received the pre-treatment with the CRL1506 and MPL16, the nematodes reached the L5024 h and 48 h later, respectively, than the infection control. Further, 1 log reduction in enterococci CFU/mL of MPL16-treatednematodes was observed. The strain also restored the reproductive capacity lost by enterococcal infection. In contrast, L.plantarum CRL1506 did not reduce the bacterial load nor restored fertility. In addition, the effect of LAB on resistance to E.faecalis infection in mice immunosuppressed by malnutrition was studied. BALB/c malnourished mice were on a hypoproteindiet for 21 days, then, they were re-nourished for 7 days with a conventional balanced diet alone or supplemented with LABs.After renourishment, they were challenged with the E. faecalis 102. The infection was evaluated 48 h post-infection, bycounting the CFUs in the intestinal lavage, feces, liver, spleen, and blood. The supplementation with LAB to the conventionaldiet increased resistance against infection by E. faecalis 102, which was confirmed by a significant decrease in the CFU countsin the tissue samples. In conclusion, the MPL16 and CRL1506 strains have probiotic potential to prevent or improve E. faecalisinfections in both a 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 and adhesion sites, but not to adirect antimicrobial action of the LAB. These strains have a great potential to be used for prevention of E. faecalis infectionsin susceptible hosts.