Background Allergic Broncho-Pulmonary Aspergillosis (ABPA) is associated with known pulmonary fungal colonisation and proven response to long term anti-fungal therapy. A recent trial at our site, confirmed that anti fungal therapy was effective in a group of patients with Severe Asthma with Fungal Sensitisation (SAFS). Whether these patients have pulmonary fungal colonisation remains unknown. Previous hypotheses have indicated that bowel colonisation causes an allergic reaction leading to broncho-constriction. Our hypothesis is that patients with SAFS, who respond to anti-fungal therapy, do have airway colonisation. Aspergillus polymerase chain reaction (APCR), represent a novel and more sensitive way to detect the presence of Aspergillus.
Methods We have performed sputum APCR tests in clinical practise over the last 2–3 years. We reviewed a retrospective cohort of patients attending a Severe Asthma Service, whose results were stored on the Mycology results system. Patient notes were reviewed to determine patient’s total serum IgE’s, IgE’s specific to Aspergillus and anti fungal therapy status.
Results 77 results were logged on the microbiology of which 70 cases were available for notes review. Of these 44 (63%) were female with an average age of 57.5 years. 26 had ABPA, 42 SAFS and 2 had neither ABPA nor SAFS, but had severe asthma. Overall 57% of ABPA or SAFS patients were APCR positive. 55% of SAFS patients were APCR positive, this number increased to 68% for those who were not taking anti-fungal therapy at the time of the test. The equivalent numbers for ABPA were 65% and 70% respectively. Neither of the 2 control severe patients had positive APCR. The full data is presented in table 1.
Conclusion This data supports the concept that patients with Severe Asthma with Fungal Sensitisation (SAFS) have pulmonary colonisation with Aspergillus. Suppression of such colonisation and reduced allergic response may then be the mechanism of action for anti-fungal therapy.