Diagnosis of Invasive Pulmonary Aspergillosis by Direct Lung Tissue Aspergillus Galactomannan Antigen Detection From Aspirate by Ultrasound-guided Fine Needle Aspiration

Invasive aspergillosis is a serious and often fatal infection in patients who are neutropenic or have undergone solid organ or stem cell transplantation. However, early diagnosis of invasive aspergillosis is a challenge. Reiss and Lehmann first described the value of serum Galactomanna (GM) for diagnosis of invasive pulmonary aspergillosis in 1979. Galactomannan is a water-soluble, polysaccharide cell wall component which is released by Aspergillus during fungal growth after inhalation of Aspergillus conidia to the lung. The availability of the Platelia Aspergillus, a sandwich ELISA that has been approved by FDA in 2003 for managing patients at risk of invasive aspergillosis because of the early detection of the GM antigen. In several studies so far the specificity of the serum galactomannan assay was greater than 85%; however, variable sensitivity from 29~100% was noted over years. In addition, low values and false-negative results are seen more often in nonneutropenic and solid organ transplantation patients as opposed to severely granulocytopenic patients .There are several factors that might explain the reported difference in the performance of antigen detection, including the biological factors (non-neutropenic patients, prior exposure to antifungal agents, encapsulation abscess preventing GM leakage to the circulation, renal clearance,…etc.) and epidemiological factors (patient population, cut-off value, prevalence of infection…etc) .

In recent years, specimens of other body fluids are increasingly used for detection of Aspergillus galactomannan antigen, including urine, bronchoalveolar lavage(BAL) fluid, cerebrospinal fluid and even the tissue specimen. However, the sensitivity and specificity of the GM detection in various specimens still have considerably variation. Ultrasound-guided transthoracic aspirate is a safe and useful method for collecting specimens for accurate bacteriologic diagnosis of lung abscess and obstructive pneumonitis10. We also reported a study of diagnosis of pulmonary Cryptococosis by ultrasound guided percutaneous aspiration. We plan to perform a prospective single-center study to investigate the role of GM in the target organ (lung tissue/fluid) by using ultrasound-guided fine needle aspirate for early diagnosis invasive aspergillosis compared with the serum galactomannan.