Culture-Based Methods and Molecular Tools for Azole-Resistant Aspergillus fumigatus Detection in a Belgian University Hospital

Abstract

Azole-resistant Aspergillus fumigatus is an increasing worldwide problem with major clinical implications. Surveillance is warranted to guide clinicians to provide optimal treatment to patients. To investigate azole resistance in clinical Aspergillus isolates in our institution, a Belgian university hospital, we conducted a laboratory-based surveillance between June 2015 and October 2016. Two different approaches were used: a prospective culture-based surveillance using VIPcheck on unselected A. fumigatus (n ϭ 109 patients, including 19 patients with proven or probable invasive aspergillosis [IA]), followed by molecular detection of mutations conferring azole resistance, and a retrospective detection of azole-resistant A. fumigatus in bronchoalveolar lavage fluid using the commercially available AsperGenius PCR (n ϭ 100 patients, including 29 patients with proven or probable IA). By VIPcheck, 25 azole-resistant A. fumigatus specimens were isolated from 14 patients (12.8%). Of these 14 patients, only 2 had proven or probable IA (10.5%). Mutations at the cyp51A gene were observed in 23 of the 25 A. fumigatus isolates; TR 34 /L98H was the most prevalent mutation (46.7%), followed by TR 46 / Y121F/T289A (26.7%). Twenty-seven (27%) patients were positive for the presence of Aspergillus species by AsperGenius PCR. A. fumigatus was detected by AsperGenius in 20 patients, and 3 of these patients carried cyp51A mutations. Two patients had proven or probable IA and cyp51A mutation (11.7%). Our study has shown that the detection of azole-resistant A. fumigatus in clinical isolates was a frequent finding in our institution. Hence, a rapid method for resistance detection may be useful to improve patient management. Centers that care for immunocompromised patients should perform routine surveillance to determine their local epidemiology.KEYWORDS VIPcheck, AsperGenius, cyp51A, cyp51B, hapE A zole resistance in Aspergillus fumigatus is an emerging problem worldwide, with major epidemiological and clinical implications (1-6). Mold active triazoles are commonly used as first line treatment and prophylaxis of invasive aspergillosis (IA) (7). Mutations in the cyp51A gene, which encodes the target of azoles, the lanosterol 14␣-demethylase, represent the most commonly reported mechanism conferring azole resistance and consequently treatment failure in A. fumigatus (8-10). The most prevalent mutation (TR 34 /L98H) involves the insertion of a 34-bp tandem repeat (TR 34 ) in the promoter region of the cyp51A gene and a point mutation within the gene leading to an amino acid substitution (L98H). More recently, an additional cyp51A-mediated resistant genotype (TR 46 /Y121F/T289A) has been reported: a 46-bp tandem repeat (TR 46 ) in the promoter of cyp51A gene and two point mutations within the gene

First azole‐resistant Aspergillus fumigatus isolates with the environmental TR46/Y121F/T289A mutation in Iran

“…We report the presence of TR 46 /Y121F/T289A now also from Iran, where until now only TR 34 /L98H had been isolated . This mutation, conferring voriconazole resistance, has been reported from both environmental (China, Taiwan, United Kingdom, Colombia, France, Germany, India, the Netherlands and Tanzania) and clinical sources (Spain, United Kingdom, France, Portugal, Argentina, Taiwan, Germany, China, Japan, United States, Denmark, Belgium and the Netherlands) (Table 1). All previous studies conducted in Iran for monitoring the mechanism of resistance among azole‐resistant A fumigatus in both clinical and environmental samples showed that the TR 34 /L98H mutation was reported with increasing frequency from 3.3% in 2013 to 6.6% in 2016 .…”

Improving the diagnosis of invasive aspergillosis by the detection of Aspergillus in broncho-alveolar lavage fluid: Comparison of non-culture-based assays

“…(12,21,22) Simultaneous detection of IA and identification of resistance mutations sparks an increasing interest in clinical settings for an earlier adaptation of antifungal therapy; of note A. fumigatus resistant strains have been related to a higher mortality rate, due to a delayed initiation of adequate treatment (23) . In this context, commercial kits targeting both A. fumigatus and cyp51A genes have been recently marketed, but their evaluation on clinical samples IA population is still scarce (24,25).…”

Detecting Azole-Antifungal Resistance in Aspergillus fumigatus by Pyrosequencing

“…However, despite all this work, only three commercial kits are currently available (AsperGenius, PathoNostics, Maastricht, Netherlands, MycoGENIE, Ademtech, Pessac, France and Fungiplex ® Aspergillus Azole-R IVD PCR, Bruker Daltonik GmbH, Bremen, Germany), attesting to the difficulty of developing robust molecular assays [113]. All three commercial real-time PCRs (RT-PCR) are designed to identify the promoter region insertion polymorphisms TR34/L98H and TR46/Y121F/T289A and specific alleles [109,[114][115][116][117][118][119]. Approaches targeting polymorphisms in the cyp51A open reading frame (ORF, e.g., G54, M220, G138, G448) [120][121][122] have lagged behind.…”