Molecular methods for the diagnosis of chronic fungal rhinosinusitis
August 08 2016
A diagnosis of chronic fungal rhinosinusitis (CFRS) usually relies on the culture and histological examination of sinus samples obtained during endonasal sinus surgery. A 3-year retrospective study (Comacle et al 2016) underlines the importance of using both culture and histology because false negative results often occur by histological examination, particularly for AFRS cases where fungal hyphae may be sparse.
The authors also evaluated the sensitivity of ITS1/ITS2 PCR on sinus samples for fungal identification. All positive samples by direct examination (microscopy) were successfully amplified by PCR with a sensitivity of 100%. Molecular detection by ITS1/2 proved far superior to both culture (51% sensitivity) and histology (48% senstitivity).
Bilateral ethmoidal obstruction as a result of mucus, in a woman with allergic fungal rhinosinusitis, who also had severe asthma.
Chronic rhinitis, sometimes with nasal polyps, is a common disorder affecting an estimated 0 – 17% of all people, and many are attributable to fungi, CFRS. The sensitivity of fungal cultures from mucus is poor and specificity from nasal wash or swab also poor, as fungi are commonly cultured from the nose, as it is an air filter. Therefore the epidemiology of CFRS is likely to be under estimated. The molecular ITS1/2/method had the advantage over conventional diagnostic tests of identifying the fungal species in 46/47 samples. Aspergillus was the most commonly identified (37/47) of which 31 were A. fumigatus, whilst A. nidulans, Cladosporium cladosporoides, & Scedosporium spp. were found equally in 8.5 % of samples each. This study demonstrates that molecular tools such as PCR are important for establishing a diagnosis of CRS and for it's aetiology.