Azole resistance in Aspergillus isolates by different types of patients and correlation with environment - An Italian prospective multicentre study (ARiA study).

BACKGROUND: A wide range of frequency of azole-resistance in A fumigatus in different patient populations worldwide was observed threatening to reduce therapeutic options. OBJECTIVES: Estimate the prevalence of azole-resistance, investigate the molecular mechanisms of resistance, compare the genotypes of resistant clinical isolates with those from the surrounding environment. METHODS: Aspergillus isolates were collected by seven Italian hospital microbiology laboratories. Strains were isolated from different clinical samples from unselected patients. The azole-resistance was evaluated using screening test and microdilution EUCAST method. The molecular mechanism of resistance was performed sequencing the cyp51A gene. Resistant isolates were genotyped by microsatellite analysis and their profiles compared with those of azole-resistant isolates from previous Italian studies. RESULTS: 425 Aspergillus isolates from 367 patients were analysed. The azole-resistance rates were 4.9% and 6.6% considering all Aspergillus spp. isolates and the A fumigatus sensu stricto, respectively. All resistant isolates except one were from a single hospital. Two rare azole-resistant species were identified: A thermomutatus and A lentulus. The predominant resistance mechanism was TR34 /L98H. No correlation between the clinical resistant strains and environmental isolates from patients' home/work/ward was observed. The analysis of the molecular correlation between the resistant clinical strains collected in the present study and those of environmental and clinical origin collected in previous Italian studies reveals a progressive diversification of azole-resistant genotypes starting from a founder azole-resistant genotype. CONCLUSIONS: This study confirms the trend of azole-resistance rate in Italy, showing a geographical difference. Data reinforce the importance of surveillance programmes to monitor the local epidemiological situation.

Azole-resistant Aspergillus fumigatus in the Italian environment.

OBJECTIVES: Azole resistance in Aspergillus fumigatus environmental and clinical isolates is recognised as an emerging problem worldwide. Development of azole resistance may be environmentally driven because of the massive use of azole fungicides in agriculture. The mechanism of azole resistance is mostly related to mutations in the cyp51A gene. METHODS: A. fumigatus azole resistance in the environment was previously documented in northern Italy. This study extended the research in the agricultural environment also in central and southern Italy and investigated differences in the Italian geographical areas and in the different types of crops. RESULTS: A total of 177 samples (173 soil samples and 4 Dutch bulbs) collected in the period 2014-20117 in 14 Italian regions were analysed. Itraconazole-resistant A. fumigatus isolates grew in 16.9% of the screened samples. Differences were observed in soil samples from the three Italian geographic areas: 12.5% in the north, 15.2% in the centre and 24.1% in the south. Resistant isolates were from different cultivations, treated or officially not treated with azole fungicides. Sequencing of the cyp51A gene confirmed that resistance was mainly associated with the TR34/L98H mutation (29/30 isolates); 1 isolate showed the G54E mutation. CONCLUSIONS: The risk for patients to acquire multi-azole-resistant strains from the environment could have a serious impact on the management of life-threatening invasive infections. The azole resistance rate of 16.9% found in Italy requires suitable monitoring of antifungal susceptibility of clinical isolates.