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Background. Antimonials are the first drug of choice for the treatment of American tegumentary leishmaniasis (ATL); however, their efficacy is not predictable, and this may be linked to parasite drug resistance. We aimed to characterize the in vitro antimony susceptibility of clinical isolates of Peruvian patients with ATL who were treated with sodium stibogluconate and to correlate this in vitro phenotype with different treatment outcomes. Methods. Thirty-seven clinical isolates were obtained from patients with known disease and treatment histories. These isolates were typed, and the susceptibility of intracellular amastigotes to pentavalent (SbV) and trivalent (SbIII) antimonials was determined. Results. We observed 29 SbV-resistant isolates among 4 species of subgenus Viannia, most of which exhibited primary resistance; isolates resistant only to SbIII; and 3 combinations of in vitro phenotypes: (1) parasites sensitive to both drugs, (2) parasites resistant to both drugs, and (3) parasites resistant to SbV only (the majority of isolates fell into this category). There was no correlation between in vitro susceptibility to both antimonials and the clinical outcome of therapy. Conclusion. Antimony insensitivity might occur in a stepwise fashion (first to SbV and then to SbIII). Our data question the definition of true parasite resistance to antimonials. Further studies of treatment efficacy should apply standardized protocols and definitions and should also consider host factors. Copyright © 2006 Infectious Diseases Society of America [ABSTRACT FROM AUTHOR]

BACKGROUND: Treatment of late-stage human African trypanosomiasis (HAT) with melarsoprol can be improved by shortening the regimen. A previous trial demonstrated the safety and efficacy of a 10-day treatment schedule. We demonstrate the effectiveness of this schedule in a noncontrolled, multinational drug-utilization study. METHODS: A total of 2020 patients with late-stage HAT were treated with the 10-day melarsoprol schedule in 16 centers in 7 African countries. We assessed outcome on the basis of major adverse events and the cure rate after treatment and during 2 years of follow-up. RESULTS: The cure rate 24 h after treatment was 93.9%; 2 years later, it was 86.2%. However, 49.3% of patients were lost to follow-up. The overall fatality rate was 5.9%. Of treated patients, 8.7% had an encephalopathic syndrome that was fatal 45.5% of the time. The rate of severe bullous and maculopapular eruptions was 0.8% and 6.8%, respectively. CONCLUSIONS: The 10-day treatment schedule was well implemented in the field and was effective. It reduces treatment duration, drug amount, and hospitalization costs per patient, and it increases treatment-center capacity. The shorter protocol has been recommended by the International Scientific Council for Trypanosomiasis Research and Control for the treatment of late-stage HAT caused by Trypanosoma brucei gambiense. Copyright © 2005 Infectious Diseases Society of America [ABSTRACT FROM AUTHOR]

The current standard to assess pentavalent antimonial (SSG) susceptibility of Leishmania is a laborious in vitro assay of which the result has little clinical value because SSG-resistant parasites are also found in SSG-cured patients. Candidate genetic markers for clinically relevant SSG-resistant parasites identified by full genome sequencing were here validated on a larger set of clinical strains. We show that 3 genomic locations suffice to specifically detect the SSG-resistant parasites found only in patients experiencing SSG treatment failure. This finding allows the development of rapid assays to monitor the emergence and spread of clinically relevant SSG-resistant Leishmania parasites.

Background: Pentavalent antimonials (SbV) are the first-line chemotherapy for American tegumentary leishmaniasis (ATL). There are, however, reports of the occurrence of treatment failure with these drugs. Few studies in Latin America have compared the response to SbV treatment in ATL caused by different Leishmania species., Methods: Clinical parameters and response to SbV chemotherapy were studied in 103 patients with cutaneous leishmaniasis (CL) in Peru. Leishmania isolates were collected before treatment and typed by multilocus polymerase-chain-reaction restriction fragment-length polymorphism analysis., Results: The 103 isolates were identified as L. (Viannia) peruviana (47.6%), L. (V.) guyanensis (23.3%), L. (V.) braziliensis (22.3%), L. (V.) lainsoni (4.9%), L. (Leishmania) mexicana (1%), and a putative hybrid, L. (V.) braziliensis/L. (V.) peruviana (1%). L. (V.) guyanensis was most abundant in central Peru. Of patients infected with the 3 former species, 21 (21.9%) did not respond to SbV chemotherapy. The proportions of treatment failure (after 12 months of follow-up) were 30.4%, 24.5%, and 8.3% in patients infected with L. (V.) braziliensis, L. (V.) peruviana, and L. (V.) guyanensis, respectively. Infection with L. (V.) guyanensis was associated with significantly less treatment failure than L. (V.) braziliensis, as determined by multiple logistic regression analysis (odds ratio, 0.07 [95% confidence interval, 0.007-0.8]; P=.03)., Conclusions: Leishmania species can influence SbV treatment outcome in patients with CL. Therefore, parasite identification is of utmost clinical importance, because it should lead to a species-oriented treatment.