Opportunistic fungi in lower respiratory tract infection among immunocompromised and immunocompetent patients

Objectives: (1) to identify the opportunistic fungi from sputum and bronchial wash of patients with lower respiratory tract (LRT) infections in immunocompromised (IC) and immunocompetent (IP) patients, and apparently healthy controls, (2) to detect antibodies against Aspergillus species by double immunodiffusion test (ID). Subjects and methods: Three hundred patients suffering from LRT infections of both IC (150/300) and IP (150/300) patients were included in the study. The clinical specimens collected were samples of sputum (247), bronchial wash (80), and blood (300). The control group was 50 apparently healthy individuals, from whom sputum and blood were obtained. The identification of the isolated fungi was carried out by direct fluorescent and/or light microscopy, culture on different media, and biochemical tests. Moreover, the serums of patients with Aspergillus isolates were tested by double ID test for the detection of specific antibody. Results: One hundred eighty patients showed fungal elements in their clinical specimens (60%). Two hundred four funguses were detected, including 24 samples with 2 types of isolates. The identified fungi were encountered from both IC (60.9%) and IP (39.1%) patients with a significant difference between them (p< 0.001). Nine opportunistic genus-species were identified. Five were filamentous type namely Aspergillus spp., Penicillium spp., Cladosporium spp., Fusarium spp., and Geotrichum spp., while the other 4 were unicellular organisms including Candida spp., Saccharomyces cereviciae, Cryptococcus neoformans, and Rhodotorula rubra. In the control group, 36% showed fungal isolates in their sputa, and the ID test showed a positive result for antibody in only one patient with Aspergillus isolate. Conclusions: Many opportunistic fungi are important uncommon pathogens in LRT infections in IC patients. The ID test is of limited value for the detection of specific antibody of Aspergillus spp.