Table_3_Characterization of Metronidazole-Resistant Giardia intestinalis Lines by Comparative Transcriptomics and Proteomics.XLSX

Metronidazole (MTZ) is a clinically important antimicrobial agent that is active against both bacterial and protozoan organisms. MTZ has been used extensively for more than 60 years and until now resistance has been rare. However, a recent and dramatic increase in the number of MTZ resistant bacteria and protozoa is of great concern since there are few alternative drugs with a similarly broad activity spectrum. To identify key factors and mechanisms underlying MTZ resistance, we utilized the protozoan parasite Giardia intestinalis, which is commonly treated with MTZ. We characterized two in vitro selected, metronidazole resistant parasite lines, as well as one revertant, by analyzing fitness aspects associated with increased drug resistance and transcriptomes and proteomes. We also conducted a meta-analysis using already existing data from additional resistant G. intestinalis isolates. The combined data suggest that in vitro generated MTZ resistance has a substantial fitness cost to the parasite, which may partly explain why resistance is not widespread despite decades of heavy use. Mechanistically, MTZ resistance in Giardia is multifactorial and associated with complex changes, yet a core set of pathways involving oxidoreductases, oxidative stress responses and DNA repair proteins, is central to MTZ resistance in both bacteria and protozoa.

甲硝唑（Metronidazole, MTZ）是一类临床至关重要的抗菌抗原虫药剂，对细菌与原虫均具有抗菌活性。该药物已被广泛应用六十余载，直至此前，甲硝唑耐药的情况仍较为罕见。然而近期耐甲硝唑的细菌与原虫数量出现急剧攀升，这一现象引发了高度关注——因为目前几乎没有其他药物能够拥有与之相当的广谱活性谱。为探明甲硝唑耐药的关键影响因素与分子机制，本研究选用了临床常规以甲硝唑治疗的原虫寄生虫蓝氏贾第鞭毛虫（Giardia intestinalis）。我们通过分析与耐药性升高相关的适应性特征、转录组（transcriptome）与蛋白质组（proteome），对两株体外筛选获得的甲硝唑耐药寄生虫株及一株回复突变株进行了系统表征。此外，我们还利用已公开的其他耐药蓝氏贾第鞭毛虫分离株的数据开展了荟萃分析。综合所有分析数据可知，体外诱导产生的甲硝唑耐药性会给寄生虫带来显著的适应性代价，这或许可以部分解释为何尽管数十年间甲硝唑被大量使用，耐药性并未广泛传播。从机制层面来看，蓝氏贾第鞭毛虫的甲硝唑耐药性属于多因素介导的复杂过程，伴随多种分子层面的改变；但涉及氧化还原酶、氧化应激应答及DNA修复蛋白的核心通路，仍是细菌与原虫产生甲硝唑耐药性的共同核心机制。