Abstract

The fungal diagnostic landscape is evolving; whereas previously, traditional culture-based methods dominated, most invasive fungal disease is now diagnosed with non-culture-based tests, including direct microscopy, antigen, antibody, and molecular assays, supported by histopathology and radiology. Access to and turnaround time of diagnostic tests and their clinical implementation varies across the UK. The British Society for Medical Mycology convened an expert group to update its 2015 best practice guidance. Guidance on histopathology and radiology investigations remain unchanged from the 2015 standards of care. For each mycological test, we include test-specific commentaries and accompanying tables, with expected turnaround times (sample collection to reporting). Based on recent evidence, new or stronger recommendations include use of Pneumocystis PCR; 1,3-β-D-glucan testing for suspected invasive candidiasis and Pneumocystis pneumonia; higher volume respiratory sample cultures; Aspergillus antigen or antibody-based testing in expanded clinically vulnerable populations, including patients in intensive care units and patients with chronic respiratory disease (including asthma); use of Candida PCR and Mucorales PCR in specific contexts; pan-fungal PCR and DNA sequencing for fungal identification from positive microscopy or histopathology specimens; and inclusion of posaconazole and isavuconazole in therapeutic antifungal monitoring recommendations. We discuss integration of diagnostic tests with antifungal stewardship and common clinical scenarios. Although recommendations focus on adults and UK practice, use in paediatric populations and worldwide applicability is discussed. Recommendations are presented as auditable standards to facilitate implementation and quality improvement measures. An emphasis on integration of combined diagnostics with antifungal stewardship and clinical pathways extends guideline relevance beyond microbiology laboratories to clinicians investigating patients with multimorbidity and suspected fungal disease within increasingly complex health-care systems.