Limited evidence of fungicide-driven triazole-resistant Aspergillus fumigatus in Hamilton, Canada

Ashu, Eta Ebasi; Kim, Ga Young; Roy-Gayos, Patrick; Dong, Kelly; Forsythe, Adrian; Giglio, Victoria; Korfanty, Gregory A.; Yamamura, Deborah; Xu, Jianping

doi:10.1139/cjm-2017-0410

Cited by 13 publications

(14 citation statements)

References 32 publications

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“…A total of 195 A. fumigatus isolates were obtained from in and around Hamilton as previously described. 7 Briefly, 62 A. fumigatus isolates each were, respectively, obtained from urban parks within Hamilton and from farm fields located ~35 km west of Hamilton between September 2014 and January 2015. Fungicides with trade names Stratego, Prosaro, and Headline were used on these farms every other year for at least 10 years prior to our sampling.…”

Section: Methodsmentioning

confidence: 99%

“…In addition, all 195 isolates were subjected to genotyping using nine A. fumigatus -specific and highly polymorphic microsatellite markers. The details of their isolation and identification have been described in the study by Ashu et al 7 …”

Section: Methodsmentioning

confidence: 99%

“…Both the microsatellite genotype and the triazole susceptibility data were from a previous study. 7 The correlational tests were performed using the Mantel and Pearson correlation tests as implemented in R version 3.0 and Microsoft Excel 2010, respectively.…”

Section: Methodsmentioning

confidence: 99%

“… 6 We recently investigated whether the use of agricultural triazole fungicide causes clinical triazole resistance in Hamilton, Ontario, Canada, and noted that there was evidence of reduced itraconazole susceptibility in both clinical and agricultural A. fumigatus isolates (where the modal minimum inhibitory concentration [MIC] for both populations was 0.5 mg/L) when compared with urban park isolates (modal MIC =0.25 mg/L). 7 The results suggested that continued triazole selection pressure could drive some of the Hamiltonian isolates to become resistant to triazole antifungal drugs. Additionally, based on genotype results at nine microsatellite loci, we showed evidence for widespread sexual recombination and frequent gene flow, both of which could have a significant impact on the initiation and spread of antifungal-resistant genes throughout the Hamiltonian A. fumigatus population.…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, based on genotype results at nine microsatellite loci, we showed evidence for widespread sexual recombination and frequent gene flow, both of which could have a significant impact on the initiation and spread of antifungal-resistant genes throughout the Hamiltonian A. fumigatus population. 7 …”

Section: Introductionmentioning

confidence: 99%

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Widespread amphotericin B-resistant strains of Aspergillus fumigatus in Hamilton, Canada

Ashu¹,

Korfanty²,

Samarasinghe³

et al. 2018

IDR

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PurposeAmphotericin B (AMB) is one of the major antifungal drugs used in the management of aspergillosis and is especially recommended for treating triazole-resistant strains of Aspergillus fumigatus. However, relatively little is known about the AMB susceptibility patterns of A. fumigatus in many parts of the world. This study aims to describe the AMB susceptibility patterns in Hamilton, Ontario, Canada.MethodsThe in vitro susceptibilities of 195 environmental and clinical A. fumigatus isolates to AMB were tested by the broth microdilution method as per the Clinical and Laboratory Standards Institute’s guidelines. Catalase-generated oxygen bubbles trapped by Triton X-100 were used to quantify catalase activity in a representative group of isolates.ResultsOf the 195 isolates, 188 (96.4%) had the minimum inhibitory concentration (MIC) of AMB ≥2 mg/L, with approximately 80% and 20% of all clinical and environmental isolates having MICs of ≥ 4 mg/L. Overall, the clinical isolates were less susceptible to AMB than environmental isolates (P-value <0.001). The strain with the highest AMB MIC (16 mg/L) had one of the highest catalase activities. However, there was no correlation between AMB MIC and catalase activity in our sample.ConclusionThe widespread AMB resistance suggests that using AMB in the management of A. fumigatus infections in Hamilton would likely result in treatment failure. Although high catalase activity may have contributed to AMB resistance in some isolates, the mechanism(s) for the observed AMB resistance in Hamilton is unknown and likely complex.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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