Ashu Eta Ebasi, Kim Ga Young, Roy-Gayos Patrick, Dong Kelly, Forsythe Adrian, Giglio Victoria, Korfanty Gregory, Yamamura Deborah, Xu Jianping
a Department of Biology and the Institute of Infectious Diseases Research, McMaster University, 1280 Main Street W, Hamilton, ON L8S 4K1, Canada.
b Department of Pathology and Molecular Medicine, McMaster University, 1280 Main Street W, Hamilton, ON L8S 4K1, Canada.
Can J Microbiol. 2018 Feb;64(2):119-130. doi: 10.1139/cjm-2017-0410. Epub 2017 Nov 20.
Aspergillus fumigatus is a ubiquitous opportunistic fungal pathogen that can cause aspergillosis in humans. Over the last decade there have been increasing global reports of treatment failure due to triazole resistance. An emerging hypothesis states that agricultural triazole fungicide use causes clinical triazole resistance. Here we test this hypothesis in Hamilton, Ontario, Canada, by examining a total of 195 agricultural, urban, and clinical isolates using 9 highly polymorphic microsatellite markers. For each isolate, the in vitro susceptibilities to itraconazole and voriconazole, 2 triazole drugs commonly used in the management of patients, were also determined. Our analyses suggested frequent gene flow among the agricultural, urban environmental, and clinical populations of A. fumigatus and found evidence for widespread sexual recombination within and among the different populations. Interestingly, all 195 isolates analyzed in this study were susceptible to both triazoles tested. However, compared with the urban population, agricultural and clinical populations showed significantly reduced susceptibility to itraconazole and voriconazole, consistent with ecological niche-specific selective pressures on A. fumigatus populations in Hamilton. Frequent gene flow and genetic recombination among these populations suggest greater attention should be paid to monitor A. fumigatus populations in Hamilton and other similar jurisdictions.
烟曲霉是一种普遍存在的机会性真菌病原体，可导致人类患曲霉病。在过去十年中，全球范围内因三唑耐药导致治疗失败的报告不断增加。一种新出现的假说认为，农业中使用三唑类杀菌剂会导致临床三唑耐药。在此，我们在加拿大安大略省汉密尔顿通过使用9个高度多态性微卫星标记检测总共195株农业、城市和临床分离株来检验这一假说。对于每一株分离株，还测定了其对伊曲康唑和伏立康唑（常用于治疗患者的两种三唑类药物）的体外敏感性。我们的分析表明，烟曲霉的农业、城市环境和临床群体之间频繁发生基因流动，并发现了不同群体内部和之间广泛存在有性重组的证据。有趣的是，本研究分析的所有195株分离株对所测试的两种三唑类药物均敏感。然而，与城市群体相比，农业和临床群体对伊曲康唑和伏立康唑的敏感性显著降低，这与汉密尔顿烟曲霉群体的生态位特异性选择压力一致。这些群体之间频繁的基因流动和基因重组表明，应更加关注监测汉密尔顿及其他类似地区的烟曲霉群体。
