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

VERA, MARÍA DANIELA; BLANCO, HÉCTOR ; ARCE, LORENA ; RAYA-TONETTI, MARÍA FERNANDA; MÜLLER, MELISA ; ORTIZ MOYANO, RAMIRO ; D?ALMEIDA, ROMINA ; KITAZAWA, HARUKI; VILLENA, JULIO ; VIZOSO PINTO, MARÍA GUADALUPE

Mendoza

Congreso; "LVIII Reunión Anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular"; 2022

Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular

The increase in multiresistant bacteria due to the misuse of antibiotics is a growing threat to health worldwide. Enterococcus faecalis belongs to a group of high priority bacteria resistant to antibiotics as defined by the World Health Organization. This pathogen has little pathogenic potential in the normal host, but in the elderly and immunocompromised patients it causes opportunistic infections. Because of their increasing frequency and the challenging treatment, there is a need for alternative strategies to control it. The aim of this work was to study the ability of L. plantarum MPL16 and CRL1506 strains to control E. 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 progeny was affected: most of the eggs did not hatch and the larvae did not develop normally. Further, the survival decreased [lethality of 50% (L50)= 7 days]. When they received the pre-treatment with the CRL1506 and MPL16, the nematodes reached the L50 24 h and 48 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 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 hypoprotein diet 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, by counting the CFUs in the intestinal lavage, feces, liver, spleen, and blood. The supplementation with LAB to the conventional diet increased resistance against infection by E. faecalis 102, 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 both a vertebrate and an invertebrate model. Since the probiotic effect was only observed in vivo, we postulate that it may be related to the modulation of innate immunity and/or competition for nutrients and adhesion sites, but not to a direct antimicrobial action of the LAB. These strains have a great potential to be used for prevention of E. faecalis infections in susceptible hosts