The anti-parasitic effect of probiotic bacteria via limiting the fecundity of Trichinella spiralis female adults

A potential protective effect of probiotic strains against zoonotic Trichinella spiralis infection was investigated in the framework of a new therapeutic strategy aimed at using probiotics to control parasitic zoonoses. The study was focused on the impact of six selected probiotic (bacteriocinogenic) strains on the intensity of T. spiralis infection and female fecundity ex vivo and in vitro. Bacterial strains of different origin (Enterococcus faecium EF55, Enterococcus faecium 2019 = CCM7420, Enterococcus faecium AL41 = CCM8558, Enterococcus durans ED26E/7, Lactobacillus fermentum AD1 = CCM7421, Lactobacillus plantarum 17L/1) were administered daily in a dose of 10⁹ CFU/ml in 100 μl, and mice were infected with 400 T. spiralis larvae on day 7 of treatment. Female adults of T. spiralis were isolated on day 5 post infection (p.i.) and subsequently were used in fecundity test ex vivo. E. faecium CCM8558, E. faecium CCM7420 and E. durans ED26E/7 strains significantly reduced the number of adults in the intestine. The application of L. fermentum CCM7421, L. plantarum 17L/1, E. faecium CCM8558 and E. durans ED26E/7 caused a significant decrease in the number of muscle larvae. The treatment with E. faecium CCM8558 and E. durans ED26E/7 showed the highest inhibitory effect on female fecundity (94 %). The number of newborn larvae (NBL) was also significantly decreased after administration of L. fermentum CCM7421 and L. plantarum 17L/1 (80 %). A direct impact of probiotic strains on female reproductive capacity was examined in vitro in females isolated from untreated infected mice on day 5 p.i. A correlation was found between the inhibitory effect and the concentration of probiotic strains. The reduction effects of the strains manifested as follows: L. fermentum CCM7421 (93 %), E. faecium CCM8558, L. plantarum 17L/1, E. faecium EF55 (about 80 %), E. faecium CCM7420 and E. durans ED26E/7 (about 60 %).