The Evaluation of Clinical Utility of Platelia Aspergillus Antigen Immunoassay for Diagnosis of Invasive Aspergillosis / 대한임상미생물학회지

ABSTRACT

BACKGROUND: Because the mortality rate of invasive aspergillosis (IA) is more than 50%, an early diagnosis and appropriate management are important to achieve a favorable outcome. Aspergillus galactomannan(AG)antigen test has recently been introduced for diagnosis and monitoring of IA. This study was to evaluate the clinical utility of AG detection in diagnosis of IA. METHODS: One hundred and seventy-five samples from 149 patients were tested for AG during the period from September 2004 to May 2005 and the results were evaluated retrospectively. IA was diagnosed into 'proven','probable'and 'possible', groups based on patients' clinical laboratory findings as per European Organization for Research and Treatment of Cancer/Mycoses Study Group. AG was tested using a Platelia Aspergillus antigen ELISA (Bio-Rad, Hercules, CA, USA); the optical density (OD) of the test specimen was divided by the mean OD of two cut-off controls. The test was classified as positive when the OD ratio was > or =1.5; ratios 1-1.5 were classified as equivocal. Clinical Information was obtained from the electronic medical records of the patients. RESULTS: Of the 175 samples tested, 19 were positive, 14 equivocal, and 142 negative for AG. A number of the 'proven', 'probable', and 'possible'IA patients were 2, 15, and 28, respectively. At the OD ratio of 1.5, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 76.9%, 94.7%, 58.8%, and 97.7%, respectively, when 4 false-negative patients treated with amphotericin B before Aspergillus antigen test were excluded. CONCLUSION: The Platelia Aspergillus ELISA demonstrated an excellent sensitivity, specificity and NPV for the diagnosis of IA. A combined use of the antigen test with microbiological and clinical evaluation might facilitate the early diagnosis of IA and, consequently, improve its clinical outcome.