Evaluation of fungal colonization and specific IgG against Aspergillus fumigatus in patients with pulmonary tuberculosis

Background and purpose: Aspergillus is a ubiquitous fungus, which causes a wide spectrum of infections including invasive pulmonary aspergillosis (IPA), depending on the patient's immune status and underlying lung disease. Among the Aspergillus spp, A. fumigatus remains the predominant agent of IPA. In patients with a preexisting lung cavity from a variety of causes, such as pulmonary tuberculosis (TB) Aspergillus can colonize and grow into the cavity to form a pulmonary aspergilloma. In this present study we assessed TB patients for aspergilloma based on culture and non-culture based methods Materials and methods: During one year, we studied 124 patients with TB at Massih Daneshvari hospital from Tehran, Iran. Sputum specimens were analyzed by direct microscopic examination (DME) with 20% potassium hydroxide. These samples were also processed for fungal culture. The clinical and radiological features or CT-scan report of all patients were recorded. All patients were screened for serum specific IgG against A. fumigatus, using Aspergillus IgG ELISA Kit (Genesis Diagnostics Ltd, Cambridgeshire, UK). The results are expressed in U/mL. IgG 12 U/mL was considered as positive result based on kit manufacturer instruction. Results: Out of 124 patients with tuberculosis (66 male, 58 female, age range: 10-91 years), 54 had abnormal chest radiographic findings. Chest X-ray findings showed that 48 patients (38.7%) exhibited residual cavities (31 cases in right lobe, 10 in left lobe and 7 in both lung). Round shaped mass lesion was detected only in 6 patients (6.8%). DME of sputum was positive in 10 patients for septate fungal hyphae. A. fumigatus was grown from 14 samples of TB patients. Out of 124 TB patients, 55(44.3%) cases were positive for specific serum IgG against A. fumigatus. There was a significant relationship between positive culture, DME and serum IgG profile level (P< 0.05). Totally, three patients (2.4%) met criteria for aspergilloma Conclusion: Colonization with Aspergillus in preexisting lung cavity produced by TB should be considered as a risk factor for aspergilloma