Miltefosine and Antimonial Drug Susceptibility of Leishmania Viannia Species and Populations in Regions of High Transmission in Colombia

BackgroundPentavalent antimonials have been the first line treatment for dermal leishmaniasis in Colombia for over 30 years. Miltefosine is administered as second line treatment since 2005. The susceptibility of circulating populations of Leishmania to these drugs is unknown despite clinical evidence supporting the emergence of resistance.Methodology/Principal FindingsIn vitro susceptibility was determined for intracellular amastigotes of 245 clinical strains of the most prevalent Leishmania Viannia species in Colombia to miltefosine (HePC) and/or meglumine antimoniate (SbV); 163, (80%) were evaluated for both drugs. Additionally, susceptibility to SbV was examined in two cohorts of 85 L. V. panamensis strains isolated between 1980–1989 and 2000–2009 in the municipality of Tumaco. Susceptibility to each drug differed among strains of the same species and between species. Whereas 68% of L. V. braziliensis strains presented in vitro resistance to HePC, 69% were sensitive to SbV. Resistance to HePC and SbV occurred respectively, in 20% y 21% of L. panamensis strains. Only 3% of L. V. guyanensis were resistant to HePC, and none to SbV. Drug susceptibility differed between geographic regions and time periods. Subpopulations having disparate susceptibility to SbV were discerned among L. V. panamensis strains isolated during 1980–1990 in Tumaco where resistant strains belonged to zymodeme 2.3, and sensitive strains to zymodeme 2.2.Conclusions/SignificanceLarge scale evaluation of clinical strains of Leishmania Viannia species demonstrated species, population, geographic, and epidemiologic differences in susceptibility to meglumine antimoniate and miltefosine, and provided baseline information for monitoring susceptibility to these drugs. Sensitive and resistant clinical strains within each species, and zymodeme as a proxy marker of antimony susceptibility for L. V. panamensis, will be useful in deciphering factors involved in susceptibility and the distribution of sensitive and resistant populations.

背景 五价锑剂（pentavalent antimonials）作为哥伦比亚皮肤利什曼病的一线治疗方案已沿用超30年。自2005年起，米替福新（miltefosine，HePC）被列为二线治疗药物。尽管已有临床证据表明耐药性正在出现，但目前对于循环利什曼原虫种群对这些药物的敏感性仍不明确。
研究方法与结果 本研究对哥伦比亚境内流行的245株最常见的维亚尼亚利什曼原虫（Leishmania Viannia）临床菌株的细胞内无鞭毛体开展体外敏感性测定，检测其对米替福新（HePC）和/或葡萄糖酸锑钠（meglumine antimoniate，SbV）的敏感性；其中163株（占总菌株数的80%）同时接受了两种药物的敏感性评估。此外，本研究针对1980-1989年及2000-2009年在图马科市分离的两批各85株巴拿马维亚尼亚利什曼原虫（L. V. panamensis）菌株，检测了其对SbV的敏感性。
结果显示，同一物种的不同菌株间以及不同物种间，对药物的敏感性均存在差异。68%的巴西维亚尼亚利什曼原虫（L. V. braziliensis）菌株对HePC表现出体外耐药性，而69%的菌株对SbV敏感。在巴拿马维亚尼亚利什曼原虫菌株中，分别有20%与21%的菌株对HePC和SbV产生耐药性。仅3%的圭亚那维亚尼亚利什曼原虫（L. V. guyanensis）菌株对HePC耐药，未发现对SbV耐药的菌株。药物敏感性还存在地理区域和时间层面的差异。在1980-1990年于图马科市分离的巴拿马维亚尼亚利什曼原虫菌株中，可区分出对SbV敏感性存在差异的亚群：耐药菌株属于酶型（zymodeme）2.3，敏感菌株则属于酶型2.2。
研究结论与意义 本研究对维亚尼亚利什曼原虫临床菌株开展的大规模敏感性评估，揭示了该属物种、种群、地理区域及流行病学层面在对葡萄糖酸锑钠与米替福新敏感性上的差异，并为监测这两种药物的敏感性提供了基线数据。各物种内的敏感与耐药临床菌株，以及可作为巴拿马维亚尼亚利什曼原虫锑剂敏感性替代标志物的酶型，将有助于解析与药物敏感性相关的影响因素，以及敏感与耐药种群的分布特征。