Background: Toxoplasma gondii transmission can occur during pregnancy if the mother contracts the infection for the first time. Treatment strategies include the use of antimicrobial medications and providing supportive care. Spiramycin is commonly used to treat toxoplasmosis in pregnant women and to hinder the disease's transmission. However, its ability to treat the fetus is questionable due to its limited capacity to cross the placental barrier. Additionally, economic constraints and sanctions may impede access to this medication. Objectives: Consequently, in search of an effective treatment, for the first time in Iran, the effectiveness of clindamycin in preventing abortion and vertical transmission of the PRU strain of T. gondii infection in pregnant mice was evaluated. Methods: On the twelfth day of gestation, pregnant mice were exposed to T. gondii and subsequently received treatment with either clindamycin or spiramycin. This resulted in the establishment of four distinct groups: A normal control group, an infected group without treatment, an infected group treated with clindamycin, and another infected group treated with spiramycin. Following these interventions, a series of parasitological evaluations (including microscopic examination and real-time PCR), histopathological evaluations, and immunological assessments were conducted. Results: The findings showed a significant reduction in the number of cysts in the eye and brain (ranging from 77.32% to 90.72%) among the groups treated with clindamycin and spiramycin compared to the control group. Furthermore, treatment with clindamycin, like treatment with spiramycin, was able to suppress inflammatory changes, prevent cell death, and reduce vascular cuffs in the brain, as well as decrease bleeding, placental thrombosis, and the accumulation of inflammatory cells in the placenta. Clindamycin was also effective in diminishing retinal folds, tiny retinal bleeds, and cell vacuolation in eye tissues. Immunologically, treatment in both the spiramycin and clindamycin groups resulted in a decrease in the level of the cytokine TNF-α, indicating an increase in the cellular immune response. In addition, increased levels of IL-10 in the treated infected groups could contribute to the reduction of TNF-α production. Conclusions: Typically, spiramycin is the first choice for treating congenital toxoplasmosis, but clindamycin can be a useful substitute or additional treatment when resistance to primary medications occurs, when there is intolerance, or when access to the main drugs is restricted.
