Evaluation of the potential therapeutic efficacy of <i>Lactobacillus rhamnosus</i> in ratsexperimentally infected with <i>Blastocystis hominis</i>

Abstract Blastocystis hominis (Blastocystis) is a common intestinal protist found in humans and various animals globally. Although its implications for health and diseases remains controversial, it has been suggested to be associated with gastrointestinal disorders, including abdominal pain and diarrhea, as well as cutaneous lesions such as urticaria. While metronidazole (MTZ) remains the primary treatment for blastocystosis, it is accompanied by several adverse effects. This underscores the pressing need for a safe therapeutic alternative, and probiotics emerge as a promising candidate. Probiotics exhibit the ability to treat gastrointestinal infections by modifying the composition of the gut microbiota and influencing the host’s immune response. Lactobacillus rhamnosus (L. rhamnosus) has demonstrated efficacy against several parasitic diseases such as giardiasis and toxocariasis. The present study aims to evaluate the in vivo anti- Blastocystis activity of L. rhamnosus in comparison to MTZ. Twenty-eight Sprague- Dawley rats were divided into four groups (seven rats per group), all infected with Blastocystis, except for the non-infected group 1 (G1). The treatment duration was 7 days for MTZ and 10 days for L. rhamnosus. The therapeutic efficacy was assessed through parasitological follow-up of fecal and intestinal fluid parasitic counts on the 3rd, 6th, 9th, and 12th days post-treatment, along with histopathological evaluation of selected segments of the ileum and colon. L. rhamnosus induced a statistically significant reduction in fecal and intestinal fluid parasitic counts compared to MTZ, accompanied by normalized villous architecture and restoration of the villous to crypt ratio. Hence, this study highlights the potential therapeutic effectiveness of L. rhamnosus as a safe alternative against blastocystosis.