Weekly Fungal Diagnostics Update

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Overall summary

This week’s fungal diagnostics literature is led by two clinically important Aspergillus papers: new proposed diagnostic criteria for invasive pulmonary aspergillosis (IPA) in COPD, and a prospective study comparing multiplex Aspergillus IgG testing with standard Aspergillus fumigatus IgG for chronic pulmonary aspergillosis (CPA).

Other papers highlight important developments in PCR, targeted next-generation sequencing, metagenomic sequencing, MALDI-TOF, nanopore sequencing and lateral flow assay interpretation. Several of these are promising, but should be treated cautiously until full diagnostic performance and implementation data are reviewed.

High priority

1. Diagnostic criteria for invasive pulmonary aspergillosis in COPD patients

Denning DW et al.
American Journal of Respiratory and Critical Care Medicine, 2026
DOI: 10.1093/ajrccm/aamag310

This international consensus paper proposes COPD-specific diagnostic criteria for invasive pulmonary aspergillosis in hospitalised patients with acute COPD exacerbations. The suggested pathway focuses on high-risk COPD patients and recommends CT imaging plus respiratory fungal microscopy and culture, Aspergillus PCR where available, bronchoscopy or BAL galactomannan, serum galactomannan and Aspergillus IgG.

Why it matters: COPD patients with IPA often do not fit classic invasive fungal disease definitions, and Aspergillus-positive respiratory samples may be dismissed as colonisation. These proposed criteria could help clinicians identify patients who need earlier fungal investigation.

Clinical relevance: This is the strongest practice-facing paper this week. It may help standardise when to investigate hospitalised COPD exacerbation patients for IPA.

Limitations: These are proposed consensus criteria developed using Delphi methodology, not yet prospectively validated diagnostic criteria. Further studies are needed before they can be treated as definitive.

2. Diagnostic performance of IgG against multiplex Aspergillus antigens for identifying chronic pulmonary aspergillosis

Sehgal IS et al.
Medical Mycology, 2026
DOI: 10.1093/mmy/myag071

This prospective diagnostic study compared a multiplex Aspergillus IgG assay with standard A. fumigatus IgG for diagnosing CPA. Although the multiplex assay included antigens from several Aspergillus species, it performed worse than conventional A. fumigatus IgG.

Why it matters: Broader antigen panels sound attractive, but this study suggests they should not replace standard A. fumigatus IgG as a first-line CPA serology test.

Clinical relevance: The findings support continued use of A. fumigatus IgG as the main serological test for CPA. Sequential testing with A. flavus IgG may deserve further evaluation in selected settings.

Limitations: The study was conducted in a tertiary chest clinic with a high prevalence of CPA, so results may differ in lower-prevalence settings.

Medium priority

3. Clinical validation of a new multi-Aspergillus species RT-qPCR assay

Clinical Microbiology and Infection, 2026
DOI: 10.1016/j.cmi.2026.03.023

This paper reports clinical validation of a multi-species Aspergillus RT-qPCR assay. A well-validated molecular assay could be useful where rapid Aspergillus detection is needed alongside culture, microscopy and galactomannan testing.

Why it matters: Molecular diagnostics are increasingly important in invasive aspergillosis, especially where conventional tests are slow or insensitive.

Caution: Full performance details are needed before making strong claims about sensitivity, specificity, specimen type or implementation readiness.

4. Cross-reactivity of Cryptococcal Antigen Lateral Flow Assay with basidiomycetous yeasts

Medical Mycology, 2026
DOI: 10.1093/mmy/myag070

This paper examines cross-reactivity of the cryptococcal antigen lateral flow assay with basidiomycetous yeasts. It highlights an important cause of potential false-positive cryptococcal antigen results.

Why it matters: False-positive CrAg results can lead to misdiagnosis, unnecessary treatment and delayed recognition of the true pathogen.

Clinical relevance: This is particularly relevant for microbiology, infectious diseases, haematology, HIV and transplant services, especially when CrAg positivity does not fit the clinical picture.

Caution: The full paper is needed to confirm which organisms cross-reacted, how often, and under what test conditions.

5. Diagnostic value and clinical performance of targeted next-generation sequencing for lower respiratory tract infections

Journal of Infection, 2026
DOI: 10.1016/j.jinf.2026.106785

This real-world prospective study evaluates targeted next-generation sequencing for lower respiratory tract infections. The approach may offer a middle ground between narrow PCR tests and broad metagenomic sequencing.

Why it matters: Targeted NGS could be useful in complex pneumonia, ICU infection and immunocompromised patients, particularly when conventional microbiology is negative or slow.

Caution: For this update, it should be presented cautiously unless fungal yield, comparator testing and clinical impact are clearly reported in the full text.

Lower priority / emerging diagnostics

6. Metagenomic next-generation sequencing in mucormycosis

Microbial Pathogenesis, 2026
DOI: 10.1016/j.micpath.2026.108553

This study uses metagenomic next-generation sequencing to examine mucormycosis cases and clinicopathological features.

Why it matters: Mucormycosis is difficult to diagnose and time-critical. mNGS may help identify invasive mould infection when culture and histopathology are delayed or inconclusive.

Caution: The paper should be treated as emerging evidence unless it demonstrates clear diagnostic accuracy, faster diagnosis or measurable clinical impact.

7. Rapid identification of Sporothrix brasiliensis by MALDI-TOF MS directly from clinical cultures

Brazilian Journal of Microbiology, 2026
DOI: 10.1007/s42770-026-01996-8

This paper evaluates MALDI-TOF MS identification of Sporothrix brasiliensis directly from clinical cultures in an Amazonian epidemic setting.

Why it matters: Faster species identification can support outbreak response and laboratory capacity in regions where zoonotic sporotrichosis is expanding.

Clinical relevance: Most relevant to endemic regions, reference laboratories and services expanding MALDI-TOF fungal identification databases.

8. Conventional versus nanopore approaches in onychomycosis diagnosis

Diagnostic Microbiology and Infectious Disease, 2026
DOI: 10.1016/j.diagmicrobio.2026.117348

This study compares conventional diagnostic approaches with nanopore sequencing for onychomycosis.

Why it matters: Nail fungal infection is common, but diagnosis can be slow and imperfect. Sequencing could improve organism identification, mixed infection detection and potentially treatment selection.

Caution: This should be considered emerging or specialist diagnostics until accuracy, turnaround time, contamination handling and cost-effectiveness are clearer.

What to highlight this week

  • Lead story: proposed COPD-specific diagnostic criteria for invasive pulmonary aspergillosis.
  • Most clinically useful serology paper: multiplex Aspergillus IgG did not outperform standard A. fumigatus IgG for CPA.
  • Important diagnostic caution: cryptococcal antigen LFA cross-reactivity may cause false-positive results.
  • Emerging technologies: RT-qPCR, targeted NGS, mNGS, MALDI-TOF and nanopore sequencing remain promising, but should be interpreted according to validation quality and clinical impact.

References

  1. Denning DW, Rogers TR, Takazono T, Su X, Lagrou K, White PL, et al. Diagnostic criteria for invasive pulmonary aspergillosis in COPD patients. American Journal of Respiratory and Critical Care Medicine. 2026. https://doi.org/10.1093/ajrccm/aamag310
  2. Sehgal IS, Agarwal R, Muthu V, Prasad KT, Dhooria S, Singh M, et al. Diagnostic performance of IgG against multiplex Aspergillus antigens for identifying chronic pulmonary aspergillosis. Medical Mycology. 2026. https://doi.org/10.1093/mmy/myag071
  3. Clinical validation of a new multi-Aspergillus species reverse transcriptase quantitative PCR: a diagnostic case-control study. Clinical Microbiology and Infection. 2026. https://doi.org/10.1016/j.cmi.2026.03.023
  4. Diagnostic value and clinical performance of targeted next-generation sequencing for lower respiratory tract infections: a real-world prospective study. Journal of Infection. 2026. https://doi.org/10.1016/j.jinf.2026.106785
  5. Metagenomic next-generation sequencing reveals the clinicopathological features of mucormycosis. Microbial Pathogenesis. 2026. https://doi.org/10.1016/j.micpath.2026.108553
  6. Cross-reactivity of Cryptococcal Antigen Lateral Flow Assay with Basidiomycetous Yeasts. Medical Mycology. 2026. https://doi.org/10.1093/mmy/myag070
  7. Rapid identification of Sporothrix brasiliensis by MALDI-TOF MS directly from clinical cultures in an Amazonian epidemic setting. Brazilian Journal of Microbiology. 2026. https://doi.org/10.1007/s42770-026-01996-8
  8. Comparative evaluation of conventional and nanopore approaches in onychomycosis diagnosis. Diagnostic Microbiology and Infectious Disease. 2026. https://doi.org/10.1016/j.diagmicrobio.2026.117348