- Ice pops, a common treat in hospitals, may interfere with tests used to identify a certain type of fungal infection detrimental to people with compromised immune systems.
- A molecule called galactomannan, present in three tested ice pop brands, can lead to a false-positive test result for the Aspergillus fungal infection.
- Aspergillus, the fungus in question, is generally harmless for those with healthy immune systems. However, individuals with compromised immunity can develop aspergillus-induced invasive aspergillosis leading to severe respiratory conditions.
- False-positives in identifying fungal infections can lead to unnecessary treatments, resulting in side effects, possible drug interactions, and increased costs.
- Regular consumption of certain foods like cereal, pasta, and rice as well as items like fruit and tea bags can potentially produce false-positives for a fungal infection due to the presence of galactomannan.
Doctors need to consider that frozen ice lollies, which are a usual source of comfort in hospitals, may interfere with tests aimed at identifying a certain type of fungal infection that is particularly detrimental to people with compromised immune systems, according to a study.
In a reported incident in France, an incorrect treatment course was given to a stem cell-transplant recipient due to flawed test results. Subsequent testing of three ice pop brands revealed the presence of a molecule called galactomannan that can lead to a false-positive test result.
Detection Challenges and the Need for Specific Tests
The study “underscores the problems linked with the test and emphasizes the need for more targeted tests“, shared Malcolm Richardson, a fungal disease specialist and the director of the Mycology Reference Center in Manchester, England, who was not connected with the research.
Medicine practitioners making treatment choices based on this test need to familiarize themselves with all of its potential limitations, Richardson added.
Understanding Aspergillus – The Widespread Fungus
Aspergillus, the fungus in question, is so ubiquitous that most human beings inhale its spores daily. It is present in several everyday elements like soil, plants, household dust, and some building materials, according to the U.S. National Institutes of Health.
While generally harmless for individuals with robust immune systems, individuals with compromised immunity due to conditions like AIDS or treatments like chemotherapy can develop aspergillus-induced invasive aspergillosis leading to severe respiratory conditions.
Case in Point
This research was prompted by the case of a 42 years old woman who had undergone a stem-cell transplant for a bone marrow disorder. Tests signalled that she was infected with the aspergillus fungus, despite having no symptoms, leading her to start voriconazole, an antifungal medication.
The tests turned out to be incorrect – she was not infected with the fungus. She eventually died due to a viral infection and her body’s severe reaction to the stem-cell transplant.
What Triggered The False Positive?
The investigators considered that the consumption of three or four ice pops a day by the woman (while fasting) could have been a key factor. They analyzed 37 ice pops from three different brands – Mr. Freeze, Disney and Yetigel, and found all to be high in galactomannan, a molecule that may indicate an aspergillus infection when detected in the body.
Although the investigators couldn’t gather ample information about the manufacturing process, they postulated that the molecule could have been introduced into the ice pops via food additives or sodium gluconate, an agent used to thicken and stabilize water-based frozen treats.
Other Fungal Sources
Richardson noted that other items that might contain the fungus include fruit, black pepper, tea bags, and loose tea. Several hospitals in the U.S. and Europe restrict high-risk patients from consuming such foods, he said. They also ban foods like cereal, pasta, and rice that contain galactomannan due to the potential for producing false-positives for a fungal infection.
The Perils of false-positives
Dr. David Denning, director of the National Aspergillosis Center in Manchester, who was not involved in the report, questioned, “What’s the harm if a test falsely indicates a patient is infected by the fungus?” The issue lies in the treatment, he said. Unnecessary treatment can lead to side effects, drug interactions, and increased costs.
However, missing invasive aspergillosis could be fatal, he warned. Richardson reiterated that doctors should exercise caution if a test indicates the fungal infection in the absence of symptoms, and explore all possible causes for positive galactomannan results.
For more information on aspergillosis, you can check out the U.S. National Library of Medicine.