Fungal Diagnostics Update – 5 October 2026
This week’s research highlights an important theme in fungal diagnosis: getting the right answer is not just about inventing completely new tests. Researchers are also finding ways to combine existing tests, choose better samples, detect antifungal resistance more precisely and improve the databases used to identify unusual fungi.
Combining two Aspergillus blood tests may improve diagnosis
Diagnosing invasive pulmonary aspergillosis can be particularly difficult in people who are not neutropenic — that is, people who do not have very low numbers of neutrophils.
A new study investigated whether combining two Aspergillus blood tests could improve diagnosis in these patients: Aspergillus-specific IgG antibodies and galactomannan (GM).
Aspergillus IgG on its own showed only moderate diagnostic performance. At the threshold identified by the researchers, sensitivity was 63.9% and specificity was 70.8%. The researchers therefore investigated combining Aspergillus IgG with galactomannan testing to improve diagnostic performance.
This is interesting because fungal diagnosis increasingly relies on combining several pieces of evidence rather than expecting one test to provide a definitive answer.
Why it matters: Better combinations of existing tests could help clinicians recognise invasive aspergillosis in patients in whom diagnosis is particularly difficult.
Ainiwaer A et al. Journal of Microbiology, Immunology and Infection, 2026. DOI: 10.1016/j.jmii.2026.06.003.
Does it matter which part of the blood we test?
A prospective multicentre study of intensive-care patients with suspected sepsis compared plasma and whole blood for multiplex droplet digital PCR (ddPCR).
PCR detects genetic material from microorganisms rather than waiting for them to grow in culture.
An especially interesting result concerned Candida. Whole-blood ddPCR detected Candida considerably more often than plasma ddPCR — 87.5% compared with 31.3% in the study.
Overall performance between the two sample types was similar, so this does not mean that whole blood is automatically superior for every infection. However, it suggests that the type of blood sample used can influence whether some fungal infections are detected.
Why it matters: Improving fungal diagnostics may sometimes be as much about choosing the right specimen as developing a new laboratory test.
Wu Z et al. International Journal of Infectious Diseases, 2026. DOI: 10.1016/j.ijid.2026.109015.
PCR designed to detect antifungal resistance in Cryptococcus
Researchers have developed a highly sensitive PCR approach for detecting genetic changes associated with azole resistance in Cryptococcus neoformans.
This fungus can cause serious disease, particularly cryptococcal meningitis.
One difficulty with antifungal resistance is that a patient may have a mixed fungal population containing both susceptible and resistant organisms. Resistant variants present at relatively low levels can therefore be difficult to detect.
The researchers used what are known as SuperSelective primers, designed to distinguish very small genetic differences and identify resistance-associated mutations within mixed populations.
This remains an emerging diagnostic approach rather than a routine clinical test.
Why it matters: Faster molecular detection of antifungal resistance could eventually help clinicians choose effective treatment earlier, rather than discovering resistance after treatment has failed.
Pawar S et al. Microbiology Spectrum, 2026. DOI: 10.1128/spectrum.01166-26.
Even sophisticated identification systems depend on good databases
MALDI-TOF mass spectrometry has transformed microbiology laboratories by allowing microorganisms to be identified rapidly from their molecular “fingerprint”.
But the machine can only recognise organisms that are represented adequately in its reference database.
An international study investigated Tardiomyces blankii, an uncommon emerging fungal pathogen previously known as Candida blankii, and related species.
The researchers found that improving the MALDI-TOF reference databases markedly improved identification of these unusual fungi.
This illustrates a wider issue in fungal diagnostics. Rare and newly recognised fungi may be misidentified not because the laboratory technology is poor, but because the reference information available to that technology is incomplete.
Why it matters: As fungal taxonomy changes and new pathogens emerge, diagnostic databases need to evolve with them.
Paumier M et al. Journal of Clinical Microbiology, 2026. DOI: 10.1128/jcm.00419-26.
Research to watch: rapid PCR for an emerging dermatophyte
Another study reports a new real-time PCR assay for rapidly identifying Trichophyton mentagrophytes genotype VII (TmVII).
TmVII is an emerging dermatophyte associated with persistent inflammatory skin infections and has increasingly been associated with sexual transmission.
The new assay was designed to distinguish this genotype from closely related fungi. In laboratory testing it detected very small quantities of fungal DNA and showed no cross-reactivity with the other fungal pathogens tested.
This does not yet mean that the assay will become a routine diagnostic test, but it demonstrates how molecular diagnostics can respond quickly when new fungal pathogens or variants emerge.
Zhao J et al. Journal of Clinical Microbiology, 2026. DOI: 10.1128/jcm.00739-26.
What have we learned this week?
These studies illustrate several different routes towards better fungal diagnosis.
Sometimes the answer may be combining existing biomarkers, as with Aspergillus IgG and galactomannan. Sometimes it may involve testing a better sample, as suggested by the whole-blood ddPCR results for Candida. Molecular methods may increasingly help laboratories detect antifungal resistance, while technologies such as MALDI-TOF depend on continually improving databases to recognise rare and emerging fungi.
Together, they show that improving fungal diagnosis is not one technological breakthrough. It is a continuing process of making every stage — sampling, detection, identification and resistance testing — more accurate.