Can we improve TAT for fungal disease diagnostics?
Clinicians say: lack of diagnostic tests, or long TAT of tests, is a main issue when managing patients with suspected invasive fungal infections.
Evidence of sub-optimal mycology practice in UK laboratories
In recent years there have been increasing reports of invasive fungal disease and the emergence of more intrinsically resistant species of pathogenic fungi, such as Candida auris. ESPAUR initiated an analysis of current practices in diagnosis and treatment of mycological infections. Key findings published in their 2019 report ‘National mycology laboratory diagnostic capacity for invasive fungal diseases in 2017' (PMID: 31233810) included;
There is a need to improve the UK diagnostic capacity for invasive fungal diseases.
A minority of laboratories have local access to β-glucan and galactomannan testing
Susceptibility testing of Aspergillus is currently conducted by few laboratories
Whilst 77% of respondent’s susceptibility test Candida spp. on-site, 81% referred Aspergillus susceptibility testing. Most respondents did not do susceptibility tests for Aspergillus isolated from patients on treatment. 13% tested where ABPA was involved, 16% for aspergilloma and 22% for chronic aspergillosis.Of the laboratories that test for antifungal susceptibility on Yeasts 57% used microdilution 43% used Vitek, 32% used E-test and 29% used disks. Of the 19% that did test Aspergillus 51% used microdilution, 31% used E-test and 43% used sequencing.
EUCAST; It is recommended that broth microdilution is used to perform antifungal susceptibility testing of yeasts and moulds. The MICRONAUT antimycotic products are unique, they offer protocols for rapid growing (e.g. Candida albicans and slow growing (e.g. filamentous fungi) organisms. MICRONAUT broth microdilution plates have been evaluated for use with Aspergillus in a UK laboratory.
The survey showed that fungal diagnostics were not available in most laboratories. β-D-Glucan was only available in 5% of responding laboratories, similarly Aspergillus serum galactomannan was only available in 21% and16% for BAL galactomannan. Aspergillus antibody testing was also mainly referred – as was Cryptococcal antigen testing – both 63%. 14% of laboratories performing Cryptococcus antigen test used lateral flow tests whilst 24% used an agglutination technique.
Many laboratories are sending yeasts and moulds to reference laboratories for susceptibility testing. Mean Turnaround -Time for yeasts quoted by one reference laboratory is 6 days whilst for moulds it quotes 8 days. In-house susceptibility testing of yeasts and moulds should be 1-2 days offering a significant area for improvement.
Lateral flow assays give the laboratory the means to provide diagnostic guidance to clinicians quickly The Manchester mycology group evaluated a qualitative lateral flow assay for IgG and IgM antibodies to Aspergillus with excellent results. although a qualitative rather than a quantitative test. Likewise, the LFAs from ERA Biology for Aspergillus galactomannan, Candida mannan and Cryptococcal capsular polysaccharide could provide the prompt support that clinicians are looking for.
As the pandemic erupted and the world rushed to produce laboratory tests, three categories emerged – molecular, rapid antigen detection and antibody detection. BioConnections supply products in each of these categories plus third party controls.
We hope you find this information useful. If you would like any additional information or guidance, please get in touch - we would be delighted to assist and show you more. We are about to add B-D-glucan and RT-PCR to our mycology range, please take this opportunity to register your interest.
The BioConnections Team
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