The aim of the present paper was to evaluate the larvicidal effect of
Enterococcus faecalis
CECT7121 (
Ef7121) on the
Toxocara canis
cycle both in vitro and in vivo. For the in vitro experiments,
T. canis larvae were incubated with the supernatants of
Ef7121 (EI) and mutant
Ef7121 (EIm), in a pre-culture of
Ef7121 (EII) and in a fresh culture with
Ef7121 (EIII) and the
Ef7121 mutant strain (EIIIm). The viability of the larvae was calculated after a 48 h incubation. A significant reduction of the viability of
T. canis larvae was observed in EI, EII and EIII. A decrease of this inhibitory effect was observed in EIm and EIIIm (p = 0.008). In the in vivo experiments, mice were orally inoculated with three doses of
Ef7121. To study the probiotic persistence in the intestine, the animals were sacrificed every four days and their intestines were dissected. The initial average bacterial levels were 9.7 x 10
4 for
Ef7121 (colony forming units/g). At the end of the assay the levels were 1.46 x 10
4. No bacterial translocation was detected in mesenteric lymphatic nodules and spleen.
Ef7121 interference with the biological cycle was evaluated in mice challenged with
T. canis. The interference was significant when the mice were challenged with probiotic and
T. canis simultaneously (p = 0.001), but it was not significant when the challenge was performed 15 days after administration of the bacterial inoculum (p = 0.06). In conclusion,
Ef7121 possessed in vitro and in vivo larvicidal activity.
