This Week in Fungal Diagnostics: A New ABPA Score, Aspergillus Misidentification and Respiratory Testing
This week’s research looks at several important challenges in diagnosing fungal disease: recognising ABPA more accurately, identifying unusual Aspergillus species, interpreting fungal findings alongside bacterial results, and reducing exposure to airborne fungi in healthcare settings.
These studies are mostly early or specialist research. They may improve future diagnosis, but they do not mean that existing tests or treatment pathways should be changed immediately.
A new diagnostic score for allergic bronchopulmonary aspergillosis
Researchers have developed and validated a weighted diagnostic score for allergic bronchopulmonary aspergillosis (ABPA).
Diagnosing ABPA can be difficult because many of its features overlap with asthma, bronchiectasis and other allergic or inflammatory lung conditions. Symptoms such as cough, wheeze and mucus production are not specific to ABPA, while blood tests and scans need to be interpreted together.
A weighted score aims to bring several pieces of information together, giving greater importance to findings that are more strongly associated with ABPA. This may help clinicians make a more consistent diagnosis, particularly when no single test provides a clear answer.
A diagnostic score is intended to support clinical judgement rather than replace it. Doctors still need to consider the whole clinical picture, including symptoms, imaging, total and specific IgE, eosinophils, Aspergillus-specific testing and the presence of bronchiectasis or mucus plugging.
Why some Aspergillus species are difficult to identify
A retrospective case series examined Aspergillus latus, an emerging hybrid species within the Aspergillus section Nidulantes.
Aspergillus latus closely resembles related species, which means that routine laboratory methods may not always identify it correctly. More detailed genetic testing may be needed when an unusual or resistant isolate is suspected.
Accurate identification matters because different Aspergillus species can have different patterns of antifungal susceptibility and may be associated with different clinical outcomes. Misidentification could therefore affect both treatment decisions and our understanding of how common particular species are.
This was a small retrospective case series, so it cannot tell us how frequently A. latus occurs in the wider population. It does, however, highlight the increasing importance of specialist fungal laboratories and molecular identification.
Why fungal test results need clinical interpretation
A review in mBio examines the interactions between fungi, bacteria and the wider microbial community in the respiratory tract.
The airways can contain complex communities of bacteria and fungi, particularly in people with bronchiectasis, cystic fibrosis or other chronic lung diseases. Aspergillus may be detected alongside bacteria such as Pseudomonas aeruginosa or Staphylococcus aureus.
A positive culture or molecular test does not automatically prove that a microbe is causing disease. It may represent active infection, colonisation or part of a more complicated interaction between several organisms and the damaged airway.
This is why clinicians generally interpret fungal test results alongside symptoms, CT scans, lung function, inflammatory markers and the results of other microbiology tests.
The review may help explain why the same laboratory result can have different meanings in different patients.
Fungal infection after heart transplantation
A ten-year retrospective cohort study from Australia examined invasive fungal infections in people who had received heart transplants.
People who have received solid-organ transplants are at increased risk of invasive fungal infection because of immunosuppressive treatment and other factors affecting their immune system. The risk is not necessarily constant: it can change according to the time since transplantation, the intensity of immunosuppression, other infections and complications.
Studies like this help clinicians understand which patients are most vulnerable and when targeted surveillance or investigation may be appropriate. They also provide information about the fungal species involved and the outcomes associated with infection.
The findings relate mainly to heart-transplant recipients and should not be directly applied to people with asthma, bronchiectasis, ABPA or CPA. However, they illustrate the importance of risk-based diagnosis in people whose immune systems are significantly altered.
Reducing airborne fungi in healthcare buildings
An evaluation trial examined airborne fungal and particle control in the heating, ventilation and air-conditioning system of a coastal healthcare facility.
Airborne fungi can be a particular concern for vulnerable hospital patients, including people receiving chemotherapy, transplant recipients and others with severely weakened immune systems. Humid environments may increase the challenges faced by healthcare facilities.
The study assessed fungal particles in the air and examined methods for reducing exposure through ventilation and filtration. It found that several types of environmental fungi, including Aspergillus– and Penicillium-like organisms, could be detected in the facility.
This type of research is mainly relevant to hospital infection prevention rather than everyday household exposure. It does not mean that people with chronic lung disease need to avoid all outdoor environments. Instead, it highlights why hospitals use ventilation, filtration, building maintenance and monitoring systems to protect patients at greatest risk.
What does this mean for patients?
The main message this week is that fungal diagnosis is becoming more detailed and more dependent on context.
- ABPA diagnosis may become more consistent through the use of weighted clinical scores.
- Unusual Aspergillus species may require genetic or molecular identification.
- A positive fungal test does not always prove active infection.
- Risk factors are especially important when diagnosing invasive fungal disease.
- Healthcare facilities can reduce risk by monitoring and controlling airborne fungal particles.
For people with chronic lung disease, a test result is only one part of the assessment. The meaning of a result depends on symptoms, scans, blood tests, lung function, previous diagnoses and the person’s immune status.
This article summarises early or newly published research. It is for information only and is not a substitute for medical advice.
Sources
- Development and Validation of Weighted Diagnostic Score for Allergic Bronchopulmonary Aspergillosis
- Clinical and Genomic Insights into the Allodiploid Hybrid Pathogen Aspergillus latus
- Fungal–Bacterial Interactions in the Respiratory Tract
- Invasive Fungal Infections in Heart Transplants
- Airborne Fungal and Particle Mitigation in HVAC Systems