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Dextrose-containing fluids causing false-positive serum galactomannan: a case-control study and interrupted time
Raeseok Lee1, In Young Yoo2, Eun-Jee Oh2
1Division of Infectious Diseases, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea; Vaccine Bio Research Institute, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
Objectives:
This study aimed to identify the cause of false-positive serum Aspergillus antigen galactomannan (GM) results in our centre.
Methods:
We performed a case-control study aiming to elucidate the factors associated with false-positive GM results. Independent risk factors for false-positive GM were evaluated through a multivariable regression analysis. An interrupted time series analysis was used to evaluate the effectiveness of an intervention removing the identified factors.
Results:
Among 568 patients tested, GM was positive in 130 patients of whom 97 had false-positive GM (cases). These were compared with 427 patients with true-negative GM (controls). Administration of dextrose-containing fluids within 6 days before GM testing was an independent predictor for false-positive GM results (adjusted odds ratio [aOR], 18.60; 95% CI, 8.95-38.66. An analysis of GM presence in different dextrose-containing fluids revealed positivity in 34.8% (8 of 23) (manufacturer A) and 33.3% (5 of 15) (manufacturer B) of the samples. Investigation of the manufacturing process revealed that the saccharification process employed enzymes derived from Aspergillus niger. After identifying the root cause of false positivity, GM-containing dextrose fluid use was restricted. Interrupted time series analysis showed an immediate reduction of GM false-positivity (-6.5% per week, p = 0.045) and a declining trend (-0.33% per week, p = 0.005) postintervention.
Conclusions:
Administering dextrose-containing fluids was the primary factor causing false-positive serum Aspergillus antigen GM assay results. Our investigation led to a modification of the manufacturing process of the dextrose-containing fluids.
Insights
Dextrose-containing fluids were identified as the cause of false-positive Aspergillus antigen galactomannan (GM) tests. Restricting their use significantly reduced false-positive GM results, improving diagnostic accuracy.
Area of Science:
- Clinical Microbiology
- Diagnostic Immunology
Background:
- False-positive results in Aspergillus antigen galactomannan (GM) testing can lead to misdiagnosis and inappropriate treatment.
- Identifying the source of these false positives is crucial for accurate patient management.
Purpose of the Study:
- To investigate and identify the specific cause of false-positive serum Aspergillus antigen GM results in a clinical setting.
- To implement and evaluate an intervention to mitigate these false-positive findings.
Main Methods:
- A case-control study design was employed to compare patients with false-positive GM results to those with true-negative results.
- Multivariable regression analysis identified independent risk factors, and interrupted time series analysis assessed intervention effectiveness.
- Analysis included testing of dextrose-containing fluids and investigation of manufacturing processes.
Main Results:
- Dextrose-containing fluid administration within six days prior to testing was a significant independent predictor of false-positive GM results (aOR, 18.60).
- Aspergillus niger-derived enzymes used in the saccharification process of dextrose fluids were identified as the root cause.
- Following restricted use of these fluids, a significant reduction in false-positive GM results was observed, with an immediate decrease and a sustained declining trend.
Conclusions:
- The use of dextrose-containing intravenous fluids is the primary factor contributing to false-positive serum Aspergillus antigen GM assay results.
- Modifications to the manufacturing process of dextrose-containing fluids were implemented based on study findings to prevent future false positives.
