Center for Tropical and Emerging Global Diseases, Athens, Georgia, USA.
Department of Infectious Diseases, University of Georgiagrid.213876.9, Athens, Georgia, USA.
Microbiol Spectr. 2022 Feb 23;10(1):e0189921. doi: 10.1128/spectrum.01899-21. Epub 2022 Feb 9.
The free-living amoeba Naegleria fowleri, which typically dwells within warm, freshwater environments, can opportunistically cause primary amoebic meningoencephalitis (PAM), a disease with a mortality rate of >97%. The lack of positive treatment outcomes for PAM has prompted the discovery and development of more effective therapeutics, yet most studies utilize only one or two clinical isolates. The inability to assess possible heterogenic responses to drugs among isolates from various geographical regions hinders progress in the discovery of more effective drugs. Here, we conducted drug efficacy and growth rate determinations for 11 different clinical isolates by applying a previously developed CellTiter-Glo 2.0 screening technique and flow cytometry. We found significant differences in the susceptibilities of these isolates to 7 of 8 drugs tested, all of which make up the cocktail that is recommended to physicians by the U.S. Centers for Disease Control and Prevention. We also discovered significant variances in growth rates among isolates, which draws attention to the differences among the amoeba isolates collected from different patients. Our results demonstrate the need for additional clinical isolates of various genotypes in drug assays and highlight the necessity for more targeted therapeutics with universal efficacy across N. fowleri isolates. Our data establish a needed baseline for drug susceptibility among clinical isolates and provide a segue for future combination therapy studies as well as research related to phenotypic or genetic differences that could shed light on mechanisms of action or predispositions to specific drugs. Naegleria fowleri, also known as the brain-eating amoeba, is ubiquitous in warm freshwater and is an opportunistic pathogen that causes primary amoebic meningoencephalitis. Although few cases are described each year, the disease has a case fatality rate of >97%. In most laboratory studies of this organism, only one or two well-adapted lab strains are used; therefore, there is a lack of data to discern if there are major differences in potency of currently used drugs for multiple strains and genotypes of the amoeba. In this study, we found significant differences in the susceptibilities of 11 N. fowleri isolates to 7 of the 8 drugs currently used to treat the disease. The data from this study provide a baseline of drug susceptibility among clinical isolates and suggest that new drugs should be tested on a larger number of isolates in the future.
自由生活的阿米巴原虫福氏耐格里虫通常栖息在温暖的淡水中，它可能会偶然引起原发性阿米巴脑膜脑炎（PAM），该病的死亡率超过 97%。由于缺乏对 PAM 的有效治疗方法，促使人们发现和开发更有效的治疗方法，但大多数研究仅使用一到两种临床分离株。由于无法评估来自不同地理区域的分离株对药物的可能异质反应，因此在发现更有效的药物方面进展缓慢。在这里，我们通过应用先前开发的 CellTiter-Glo 2.0 筛选技术和流式细胞术，对 11 种不同的临床分离株进行了药物疗效和生长速率的测定。我们发现，这 11 种分离株对 8 种测试药物中的 7 种药物的敏感性存在显著差异，这些药物均构成美国疾病控制与预防中心向医生推荐的鸡尾酒疗法。我们还发现，这些分离株的生长速率存在显著差异，这引起了人们对从不同患者收集的阿米巴分离株之间差异的关注。我们的研究结果表明，需要在药物测定中使用更多不同基因型的临床分离株，并强调需要针对具有普遍疗效的福氏耐格里虫分离株的更有针对性的治疗方法。我们的数据为临床分离株的药物敏感性建立了必要的基准，并为未来的联合治疗研究以及与表型或遗传差异相关的研究提供了基础，这些研究可能揭示作用机制或对特定药物的易感性。福氏耐格里虫，也被称为食脑阿米巴原虫，广泛存在于温暖的淡水中，是一种机会性病原体，可引起原发性阿米巴脑膜脑炎。尽管每年描述的病例很少，但该疾病的病死率超过 97%。在对该生物的大多数实验室研究中，仅使用一到两种适应良好的实验室菌株，因此，缺乏数据来区分目前用于多种菌株和基因型的阿米巴的药物效力是否存在重大差异。在这项研究中，我们发现 11 种福氏耐格里虫分离株对目前用于治疗该疾病的 8 种药物中的 7 种药物的敏感性存在显著差异。这项研究的数据为临床分离株的药物敏感性提供了基准，并表明未来应该在更多的分离株上测试新药。
