Attenuation and Production of the Amphotericin B-Resistant Leishmania tropica Strain

BACKGROUND: Infections caused by Leishmania are becoming major public health problems on a global scale. Many species of Leishmania around the world are obtaining resistance levels of up to 15 folds, as estimated by the World Health Organization. Leishmania showing resistance is relatively difficult to observe and maintain in laboratory settings. OBJECTIVES: The current study deals with the generation of Leishmania tropica strains that are resistant to amphotericin B (amp B). MATERIALS AND METHODS: The L. tropica strain was attenuated using continuous passaging 20 times. The infectivity of L. tropica was confirmed in BALB/c mice. The L. tropica resistant strain was produced in vitro using a continuous increase in drug pressure. The cross resistance of L. tropica to other drugs was also investigated. RESULTS: After 20 continuous passages, the BALB/c mice tested negative in the development of leishmaniasis. At a concentration of 0.1 µg/mL, L. tropica showed resistance to amp B. The newly developed promastigotes were 16 times more resistant compared to the resistance of the wild type promastigotes. The resistant L. tropica strain showed cross resistance to itraconazole and had a resistance index that was greater than five. The resistant strain displayed maximum stability for more than three months in the drug-free medium. CONCLUSIONS: The resistant strain of L. tropica can be produced in laboratories using continuous drug pressure. The attenuated resistant strain has significant implications (both medically and academically) in the ability to overcome resistance.