[The use of galactomannan detection in diagnosing invasive aspergillosis in hemato-oncological patients]

Abstract

PREMISES AND OBJECTIVES: Timely diagnosis is of critical importance for the prognosis of invasive aspergilosis (IA) patients. Over recent years, IA detection of galactomannan using the ELISA method has assumed growing importance. The objective of the study was to analyse the usability of the method in current clinical practice of a hemato-oncological ward.

Patients and methods: From May 2003 to October 2006, blood samples were taken from patients at IA risk to detect galactomannan (GM) in serum using the ELISA method. The patients who underwent the tests were classified by the probability of IA presence on the basis of the results of conventional diagnostic methods and section findings.

Results: A total of 11,360 serum samples from 911 adult patients were tested for GM presence. IA (probable/proven) was diagnosed in 42 (4.6%) of them. The rates of sensitivity, specificity, positive and negative predictive value of galactomannan detection for IA diagnosis in our ward were, respectively, 95.2%, 90.0%, 31.5% and 99.7%. The principal causes of the limited positive predictive value of the test were the high percentage of false-positive test results (mainly caused by concomitant administration of some penicillin antibiotics or Plasma-Lyte infusion solution), as well as the fact that a large percentage of patients we examined fell within the group of patients with hematological malignity with a very low prevalence of IA.

Conclusion: GM detection in serum is associated with high sensitivity and excellent negative predictive value in IA diagnosis in hemato-oncological patients. Knowledge and elimination of possible causes of false-positive results as well as focusing the screening on patients at greatest risk of infection are necessary for an even better exploitation of the test.