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Investigation of susceptibility to amphotericin B and miltefosine in clinical isolates of Leishmania spp.: in vitro and in vivo studies

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Bianca Alves Ferreira
Total Authors: 1
Document type: Master's Dissertation
Press: Campinas, SP.
Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
Defense date:
Examining board members:
Adriano Cappellazzo Coelho; Selma Giorgio; Juliana Quero Reimão
Advisor: Adriano Cappellazzo Coelho

Leishmaniasis is a neglected and endemic disease in at least 98 countries, caused by protozoa of the genus Leishmania. These protozoa are digenetic parasites and are transmitted through the bite of hematophagous insects known as sandflies. Although the disease has an eminently rural character, it has been expanding to medium and large urban areas and has become a growing public health problem in Brazil. Approximately 25,000 cases of tegumentary leishmaniasis and 3,000 new cases of visceral leishmaniasis are reported annually. Chemotherapy for leishmaniasis in Brazil is basically limited to the use of pentavalent antimonials, amphotericin B and pentamidine. These drugs have a variable clinical response, are costly, are administered parenterally, and have several side effects due to toxicity. Miltefosine was recently approved for the clinical treatment of tegumentary leishmaniasis in Brazil, a drug that has been used in the treatment of visceral leishmaniasis in Asia for nearly two decades. In this work, the in vitro susceptibility of amphotericin B and miltefosine in all endemic Leishmania species responsible for tegumentary leishmaniasis and visceral leishmaniasis in Brazil and in a panel of 14 clinical isolates of Leishmania spp. from a reference center for tegumentary leishmaniasis treatment was evaluated. The in vitro susceptibility to amphotericin B and miltefosine in clinical isolates and Leishmania strains was determined in the promastigote and intracellular amastigote forms. Results indicated a moderate variation in the susceptibility to these drugs in both forms of the parasite, with the amastigote form being more susceptible. Furthermore, a L. (L.) amazonensis resistant line to amphotericin B was selected in vitro. The in vivo assays were performed using BALB/c mice infected with the wild-type strain of L. (L.) amazonensis, the resistant line and a clinical isolate of the same species from a patient who did not respond to this drug. Animals infected with these three strains were treated with amphotericin B for 20 days intraperitoneally. For infections with the wild-type strain, treated animals showed a significant reduction in the size of the lesion and in the parasite burden in a dose-dependent manner. However, the groups of animals infected with the clinical isolate or with the resistant line did not show a reduction in the size of the lesion, nor in the parasite burden in any of the groups treated with amphotericin B. These results demonstrated that both the amphotericin B resistant line and the clinical isolate previously exposed to the drug in the clinic did not respond to the in vivo treatment of amphotericin B. These findings may contribute to assess the limitations of amphotericin B and of miltefosine for the treatment of tegumentary leishmaniasis in Brazil (AU)

FAPESP's process: 20/01948-1 - Evaluation of susceptibility in vitro of clinical and dog isolates of Leishmania spp. to alternative drugs
Grantee:Bianca Alves Ferreira
Support type: Scholarships in Brazil - Master