Outcomes of trimethoprim/ sulfamethoxazole treatment for ocular toxoplasmosis in Congolese patients.

BACKGROUND: Ocular toxoplasmosis (OT) is the leading cause of infectious posterior uveitis in several areas worldwide. The combination of Trimethoprim/Sulfamethoxazole (TMP/SMX) has been presented as an attractive alternative to the "classic' treatment therapy (Pyrimethamine/Sulfadiazine). METHODS: A prospective study was carried out between February 2020 and September 2021 in 2 ophthalmic centers in Kinshasa. This study aimed to describe TMP/SMX treatment outcomes for OT in a cohort of immunocompetent Congolese patients. RESULTS: 54 patients were included, with a mean age at presentation of 37.5 ± 13.6 years old and a Male-Female ratio of 1.45:1. Three patients (5.6%) presented a recurrence during the follow-up period. At the end of the follow-up, improvement in VA and resolution of inflammation concerned 75.9% and 77.5% of patients, respectively. Cataracts (3.7%), macular scars (3.7%), and vitreous opacities (3.7%) were the principal causes of non-improvement in VA. Treatment-related adverse events were present in 10 patients (18.5%); gastrointestinal (14.8%) and dermatological (3.7%) adverse events were the most frequent. Dermatological adverse events led to discontinuation of treatment. CONCLUSION: TMP/SMX regimen appears to be a safe and effective treatment for OT in Congolese patients. The low cost and the accessibility of the molecules make this regimen an option for treating OT in resource-limited countries.

Prevalence of Plasmodium falciparum parasites resistant to sulfadoxine/pyrimethamine in the Democratic Republic of the Congo: emergence of highly resistant pfdhfr/pfdhps alleles.

Background: In 2005, the Democratic Republic of the Congo (DRC) switched to artesunate/amodiaquine as the first-line antimalarial in response to increasing sulfadoxine/pyrimethamine resistance and adopted intermittent preventive treatment using sulfadoxine/pyrimethamine in pregnancy. Objectives: To determine the prevalence of molecular markers of sulfadoxine/pyrimethamine resistance in southwestern DRC 10 years after the new policy was instituted. Methods: From March 2014 to December 2015, blood samples were collected from symptomatic patients presenting to outpatient centres in urban and rural areas. A total of 2030 confirmed Plasmodium falciparum isolates were genotyped at codons associated with sulfadoxine/pyrimethamine resistance. Results: The prevalence of pfdhfr-N51I, C59R and S108N and pfdhps-A437G mutations was consistently high; the prevalence of the pfdhps-K540E mutation was low but increased since its first report in 2008 in the same region, reaching 17.6% by 2015. The pfdhps-A581G mutation increased from ∼4.5% in 2014 to ∼14.0% in 2015 at urban sites while in rural areas it remained low (∼4.0%). The mutations pfdhfr-I164L and pfdhps-A613S were detected for the first time in DRC. Also, 11 (0.8%) isolates revealed the presence of the newly described pfdhps-I431V mutation. Combining pfdhfr and pfdhps alleles, quintuple and sextuple mutations were observed, with the emergence of septuple (IRNI/IAGEGA)- and octuple (IRNI/VAGKGS)-mutant genotypes. Conclusions: Intermittent preventive treatment using sulfadoxine/pyrimethamine during pregnancy remains warranted in southwestern DRC. However, the expansion of pfdhps-K540E mutation and emergence of mutants that cause higher levels of sulfadoxine/pyrimethamine resistance is concerning and may present a challenge for future preventive interventions in the country.