Table_8_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）是一类临床意义重大的抗菌剂，对细菌与原生生物均具有抗菌活性。该药物已被广泛应用超过60年，直至此前其耐药性都较为罕见。然而近期耐甲硝唑的细菌与原生生物数量出现显著增长，这引发了高度关注——因为具备类似广谱抗菌活性的替代药物寥寥无几。为明确甲硝唑耐药性背后的关键因素与作用机制，我们选用了通常采用甲硝唑治疗的原生生物寄生虫——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合度特征，并结合转录组与蛋白质组检测，对两株体外筛选获得的甲硝唑耐药寄生虫株以及一株回复突变株进行了表征。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。综合分析结果表明，体外诱导产生的甲硝唑耐药性会给该寄生虫带来显著的适合度代价，这或许可以部分解释为何尽管数十年间大量使用甲硝唑，耐药性并未广泛传播。从机制层面来看，贾第鞭毛虫的甲硝唑耐药性属于多因素调控过程，伴随复杂的分子变化；但其中涉及氧化还原酶、氧化应激应答以及DNA修复蛋白的核心通路，在细菌与原生生物的甲硝唑耐药性中均发挥核心作用。