Ice pops culprit in false-positive aspergillosis test

Ice pops culprit in false-positive aspergillosis test
Ice pops culprit in false-positive aspergillosis test

HealthDay News -- Ice pops are believed to be the cause of false-positive test results on serum aspergillus antigen (galactomannan) test in a patient who underwent a stem-cell transplant, researchers have found.

"Clinicians should be aware of this unusual cause of interaction with the galactomannan test, which can result in unnecessary investigations and treatments," Nicolas Guigue, PharmD, from Hôpital Saint Louis in Paris, wrote in a letter to the New England Journal of Medicine.

He and colleagues described the case of a 42-year-old transplant recipient who had received a human leukocyte antigen-matched hematopoietic stem-cell transplant from an unrelated donor for a myeloproliferative syndrome. The patient had an increased galactomannan index 32 and 34 days after transplantation.

Galactomannan is a polysaccharide found in the mold Aspergillus, and blood levels of the compound are often used to diagnose invasive aspergillosis in patients who have underwent stem cell transplant. Galactomannans are also used as a preservative in various foods, including ice cream and salad dressing.

The patient had been fasting but reported she began consuming three to four flavored ice pops per day starting on day 29 after transplantation. The researchers initiated voriconazole on day 35.

Four flavored ice pops from the patient's supply were tested and found positive for galactomannan. After discontinuation of these ice pops, levels returned to negative within seven days, and voriconazole therapy was discontinued on day 53.

Thirty-seven ice pops from three marketed brands were tested for galactomannan. A total of three of the cultures were found to contain penicillin, most likely due to contamination of the wrapping. In all samples, regardless of brand or flavor, high levels of galactomannan were observed.

The source of galactomannan in the ice pops was undetermined, but food additives were suspected, included sodium gluconate, which is currently used as a stabilizer and thickener and is known to cause false-positive tests for galactomannan.


Reference

  1. Guigue N et al. N Engl J Med. 2013; 369:97-98.
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