Evaluation of an in-house six-well screening plate as a means of detecting phenotypic triazole resistance in St. James's Hospital, Dublin with emphasis on Aspergillus fumigatus

Abstract

Aspergillus fumigatus is a ubiquitous saprophytic mould fungus found in nature. This fungus is present in the air, in soil, in foliage in our food stock and on inanimate surfaces. For healthy individuals, A. fumigatus poses no threat to human health and lives in harmony with the general population. However, this is not always the case, as the fungus can also be responsible for causing a range of human diseases; the most deadly and serious of which is Angioinvasive aspergillosis which is seen in immunocompromised patients (Prasad et al., 2016). There are a multitude of different forms of Aspergillosis including allergic pulmonary aspergillosis, aspergilloma and the serious condition invasive pulmonary aspergillosis. This is an extremely dangerous condition characterised by pneumonia which can prove life-threatening particularly in immunocompromised patients. This occurs mostly in people with impaired immune function as a consequence of immunosuppressive treatments due to a variety of reasons such as having treatment for acute leukaemia or having received a solid organ transplant, and more recently pulmonary aspergillosis has been described in patients with severe Coronavirus Disease-19 disease (COVID-19). It is noted by Mohamed et al., 2020 that the cases of patients who had Aspergillus co infection with COVID-19 could be drastically under reported most likely due to the aggressive nature of the pandemic leading to clinical ambiguity. According to Wang et al., 2003, Wang et al., 2004 and Hwang et al., 2004 there were only four documented cases of patients having severe acute respiratory syndrome caused by SARS-CoV-1 also developing invasive aspergillosis with none of the patients being immunocompromised prior to contracting SARS-CoV-1 although they did receive corticosteroids as part of their treatment. The aim of this project was to develop and validate a 6-well screening plate that is cost-effective and yields fast (48 hours) and effective results as part of the environmental surveillance of Aspergillus at St. James?s Hospital, Dublin. The screening plates contain five different drugs currently licenced to treat a range of fungal infections (Itraconazole, Voriconazole, Posaconazole, Caspofungin, Terbinafine) and a growth control. Over the course of 6 months a variety of A. fumigatus isolates were gathered from both indoor and outdoor locations on the campus of St. James?s Hospital in Dublin as well as from a variety of food samples originating from several different countries across the globe. The isolates were then screened and analysed for triazole resistance yielding a total of 12 resistant out of over 287 A. fumigatus isolates (6 air isolates and 6 fruit & vegetable isolates).