First Investigative Study of Azole-Resistant Aspergillus fumigatus in the Environment in Burkina Faso

Azole resistance in Aspergillus fumigatus- comprehensive review

Aspergillus fumigatus is a ubiquitous filamentous fungus commonly found in the environment. It is also an opportunistic human pathogen known to cause a range of respiratory infections, such as invasive aspergillosis, particularly in immunocompromised individuals. Azole antifungal agents are widely used for the treatment and prophylaxis of Aspergillus infections due to their efficacy and tolerability. However, the emergence of azole resistance in A. fumigatus has become a major concern in recent years due to their association with increased treatment failures and mortality rates. The development of azole resistance in A. fumigatus can occur through both acquired and intrinsic mechanisms. Acquired resistance typically arises from mutations in the target enzyme, lanosterol 14-α-demethylase (Cyp51A), reduces the affinity of azole antifungal agents for the enzyme, rendering them less effective, while intrinsic resistance refers to a natural resistance of certain A. fumigatus isolates to azole antifungals due to inherent genetic characteristics. The current review aims to provide a comprehensive overview of azole antifungal resistance in A. fumigatus, discusses underlying resistance mechanisms, including alterations in the target enzyme, Cyp51A, and the involvement of efflux pumps in drug efflux. Impact of azole fungicide uses in the environment and the spread of resistant strains is also explored.

First detection of triazole-resistant aspergillus fumigatus harbouring the TR34/L98H Cyp51A mutation in Burkina Faso

BACKGROUND

Triazole-resistant Aspergillus fumigatus (TRAF) isolates are a growing public health problem with worldwide distribution. Epidemiological data on TRAF is limited in Africa, particularly in West Africa.

OBJECTIVES

This study aimed to screen for the environmental presence of TRAF isolates in the indoor air of two hospitals in Burkina Faso.

MATERIALS AND METHODS

Air samples were collected in wards housing patients at risk for invasive aspergillosis, namely infectious diseases ward, internal medicine ward, nephrology ward, pulmonology ward, medical emergency ward and paediatric ward. Sabouraud Dextrose Agar supplemented with triazoles was used to screen the suspected TRAF isolates and EUCAST method to confirm the resistance of suspected isolates. Sequencing of cyp51A gene was used to identify the resistance mechanism of confirmed TRAF isolates.

RESULTS

Of the 198 samples collected and analysed, 67 showed growth of A. fumigatus isolates. The prevalence of TRAF isolates was 3.23% (4/124). One TRAF isolate exhibited a pan-triazole resistance. Sequencing of cyp51A gene identified the TR34/L98H mutation for this pan-triazole resistant isolate. This study showed for the first time the circulation of the pan-azole resistant isolate harbouring the TR34/L98H mutation in Burkina Faso.

CONCLUSIONS

These findings emphasise the need to map these TRAF isolates in all parts of Burkina Faso and to establish local and national continuous surveillance of environmental and clinical TRAF isolates in this country.

Azole-Containing Agar Plates and Antifungal Susceptibility Testing for the Detection of Azole-Resistant Aspergillus Species in Hospital Environmental Samples

The indoor environment of hospitals should be considered as an important reservoir of azole resistant Aspergillus species. In this study, we evaluated azole-containing agar plates (ACAPs) and antifungal susceptibility testing (AFST) for the detection of azole-resistant Aspergillus species in hospital environmental samples. Between September 2021 and January 2022, environmental samples (108 instruments and 12 air) were collected from different wards of 4 educational hospitals in Mazandaran province, Iran. All samples were cultured using ACAPs. Recovered Aspergillus isolates were molecularly identified at species level using partial DNA sequencing of beta-tubulin gene. AFST of Aspergillus species was performed using the Clinical and Laboratory Standards Institute M38-A3 guideline. Screening for cyp51A mutations was also done. Overall, 18 (15.0%) isolates of Aspergillus species were recovered from ACAPs, of which Aspergillus tubingensis (50%) and Aspergillus fumigatus (38.9%) were the commonest species. No isolate of Aspergillus species grew on posaconazole (PCZ)-containing agar plates. Among the 18 Aspergillus isolated species from ACAPs, 83.3% were related to samples from instruments. Of the nine isolates of A. tubingensis, 22.2% and 44.4% isolates showed minimum inhibitory concentration (MIC) = 2 μg/mL against voriconazole (VCZ) and itraconazole, respectively; and 44.4% isolates showed MIC = 1 μg/mL against PCZ. Of the seven isolates of A. fumigatus, one (14.3%) was resistant to VCZ. This isolate showed F46Y, G54E, G138C, M172V, M220I, D255E, T289F, G432C, and G448S mutation in cyp51A. Our finding showed the emergence of high MICs in cryptic and non-fumigatus species of Aspergillus such as A. tubingensis and VCZ resistance in A. fumigatus in indoor environment of hospitals.

Presence of Aspergillus fumigatus with the TR34/L98H Cyp51A mutation and other azole-resistant aspergilli in the air of a zoological park

Antifungal-resistant fungi, including Aspergillus fumigatus and other Aspergillus species, pose an urgent threat to human and animal health. Furthermore, the environmental route of azole resistance selection due to the widespread use of azole fungicides in crop protection and other applications is a major public health issue. Although environmental surveillance of fungi is frequently performed in many zoological parks and wildlife rehabilitation centers, the antifungal susceptibility of recovered isolates is only rarely analyzed, which precludes a clear assessment of the threat posed by these fungi to captive animals. In this study, we assessed the presence of airborne azole-resistant Aspergillus spp., including the so-called 'cryptic species' (i.e., species which are phenotypically similar to more well-known aspergilli but clearly constitute different phylogenetic lineages) in a zoological park located in the city of Madrid, Spain. In general, our results revealed a low prevalence A. fumigatus and cryptic aspergilli with decreased susceptibility to azoles. However, we detected an A. fumigatus isolate with the TR34/L98H mutation in the gene encoding the lanosterol 14α-demethylase (Cyp51A), consisting of a tandem repeat of 34 base pairs in the promoter region and a lysine to histidine substitution at codon 98. Notably, this TR34/L98H mutation has been linked to the environmental route of azole resistance selection, thus highlighting the 'One Health' dimension of the emerging problem of antifungal resistance. In this context, continuous environmental surveillance of azole-resistant aspergilli in zoological parks and other similar animal facilities is recommended.

Triazole resistance in Aspergillus fumigatus isolates in Africa: a systematic review

Emergence of triazole resistance has been observed in Aspergillus fumigatus over the past decade including in Africa. This review summarizes the current published data on the epidemiology and reported mechanisms of triazole-resistant Aspergillus fumigatus (TRAF) in both environmental and clinical isolates from Africa. Searches on databases Medline, PubMed, HINARI, Science Direct, Scopus and Google Scholar on triazole resistance published between 2000 and 2021 from Africa were performed. Isolate source, antifungal susceptibility using internationally recognized methods, cyp51A mechanism of resistance and genotype were collected. Eleven published African studies were found that fitted the search criteria; these were subsequently analyzed. In total this constituted of 1686 environmental and 46 clinical samples. A TRAF prevalence of 17.1% (66/387) and 1,3% (5/387) was found in respectively environmental and clinical settings in African studies. Resistant to itraconazole, voriconazole, and posaconazole was documented. Most of the triazole-resistant isolates (30/71, 42.25%) were found to possess the TR34/L98H mutation in the cyp51A-gene; fewer with TR46/Y121F/T289A (n = 8), F46Y/M172V/E427K (n = 1), G54E (n = 13), and M172V (n = 1) mutations. African isolates with the TR34/L98H, TR46/Y121F/T289A and the G54E mutations were closely related and could be grouped in one of two clusters (cluster-B), whereas the cyp51A-M172V mutation clustered with most cyp51A- WT strains (cluster-A). A single case from Kenya shows that TR34/L98H from environmental and clinical isolates are closely related. Our findings highlight that triazole resistance in environmental and clinical A. fumigatus is a cause for concern in a number of African countries. There is need for epidemiological surveillance to determine the true burden of the problem in Africa.

Azole-resistant Aspergillus fumigatus as an emerging worldwide pathogen

Aspergillus fumigatus, a ubiquitous pathogen, causes aspergillosis in humans, especially in immunodeficient patients. Azoles are frontline antifungal drugs for treating aspergillosis. The recent global emergence of azole resistance in A. fumigatus has become a serious problem worldwide. It has arisen through two routes: long-term azole medical therapy, called the patient route, and the use of azole fungicides in its habitats especially for agricultural activities, called the environmental route. Resistant strains developed through the latter route show cross-resistance to medical azoles because of the identical molecular target Cyp51A between azole compounds used for medical treatment and agricultural disease control. In azole-resistant strains arising through the environmental route, A. fumigatus is observed frequently possessing mutations in the cyp51A gene linked to tandem repeats in the promoter region such as TR₃₄ /L98H and TR₄₆ /Y121F/T289A. Results of microsatellite genotyping analyses of resistant A. fumigatus strains have suggested a transboundary spread of this microorganism in many countries. Diverse actors are involved in the global highway of transmission. Therefore, the matter must be addressed as a "One Health" issue. This review presents a background of azole resistance in A. fumigatus and introduces newly discovered difficulties generated as this pathogen spreads worldwide. This article is protected by copyright. All rights reserved.

Triazole susceptibility of Aspergillus species: environmental survey in Lagos, Nigeria and review of the rest of Africa

Background:

Triazole resistance is an emerging problem in the management of human aspergillosis globally and can arise in Aspergillus species which have been exposed to azole fungicides in the environment. We surveyed local government and council development areas in Lagos, Nigeria, to determine the distribution of Aspergillus species in the environment and their susceptibility to locally available triazole antifungal agents. We also reviewed the literature on the subject from the rest of Africa.

Methods:

A total of 168 soil samples from six locations in Lagos, Nigeria were processed and cultured on Saboraud dextrose agar impregnated with chloramphenicol to isolate Aspergillus species. Isolates were tested for susceptibility to itraconazole and voriconazole by microbroth dilution according to the European Committee on Antimicrobial Susceptibility Testing reference method. Relevant databases were searched to identify published work pertaining to triazole susceptibility of Aspergillus species in Africa.

Results:

A total of 117 Aspergillus species were isolated. Aspergillus niger was the most frequently isolated species (42.7%). Other species isolated were Aspergillus flavus, 37 (31.6%), Aspergillus terreus, 20 (17.1%), Aspergillus fumigatus, 5 (4.3%) and Aspergillus nidulans, 5 (4.3%). All isolates were susceptible to itraconazole and voriconazole. The literature review showed documented evidence of triazole-resistant Aspergillus species from East and West Africa.

Conclusions:

We found no triazole resistance in environmental isolates of Aspergillus in Lagos, Nigeria. Nevertheless, regular surveillance in clinical and environmental isolates is necessary in the light of findings from other African studies.

Triazole-Resistance in Environmental Aspergillus fumigatus in Latin American and African Countries

Triazole-resistance has been reported increasingly in Aspergillus fumigatus. An international expert team proposed to avoid triazole monotherapy for the initial treatment of invasive aspergillosis in regions with >10% environmental-resistance, but this prevalence is largely unknown for most American and African countries. Here, we screened 584 environmental samples (soil) from urban and rural locations in Mexico, Paraguay, and Peru in Latin America and Benin and Nigeria in Africa for triazole-resistant A. fumigatus. Samples were screened using triazole-containing agars and confirmed as triazole-resistant by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) broth dilution reference method. Isolates were further characterized by cyp51A sequencing and short-tandem repeat typing. Fungicide presence in samples was likewise determined. Among A. fumigatus positive samples, triazole-resistance was detected in 6.9% (7/102) of samples in Mexico, 8.3% (3/36) in Paraguay, 9.8% (6/61) in Peru, 2.2% (1/46) in Nigeria, and none in Benin. Cyp51A gene mutations were present in most of the triazole-resistant isolates (88%; 15/17). The environmentally-associated mutations TR₃₄/L98H and TR₄₆/Y121F/T289A were prevalent in Mexico and Peru, and isolates harboring these mutations were closely related. For the first time, triazole-resistant A. fumigatus was found in environmental samples in Mexico, Paraguay, Peru, and Nigeria with a prevalence of 7-10% in the Latin American countries. Our findings emphasize the need to establish triazole-resistance surveillance programs in these countries.