Aspergillus galactomannan detection in comparison to a real-time PCR assay in serum samples from a high-risk group of patients

Comparison of real-time PCR, nested PCR, and galactomannan antigen detection by enzyme-linked immunosorbent assay in sera for diagnosis of invasive aspergillosis

Conventional methods for diagnosis of invasive aspergillosis (IA) lack sensitivity and specificity. Serological methods still have many cases of cross-reactivity. However, molecular techniques seem to arise as a rapid approach, specific and direct that could be used in the diagnosis of IA. In this study, we analyzed 88 serum samples from patients of having IA using GM-ELISA test, nested PCR with primers for the rRNA 18S of Aspergillus genus and real time PCR specific for A. fumigatus. Among the 88 samples, 64 of them had positive GM titers and 23 had positive nested PCRs; 18 of the 23 PCR-positive samples were also GM-positive. On the other hand, 18 samples were detected positive by reel time PCR; 13 positive samples were also detecting positive by nested PCR. QPCR revealed 26 % of the patients with IA, while nested PCR and galactomannan ELISA revealed respectively 34 % and 94 % of the patients with IA. Probable IA was diagnosed in 18 and possible IA was diagnosed in 6 episodes. Forty-four episodes were defined as not having IA. The positive and negative predictive values were respectively 100 %, and 88 % for QPCR, 100 % and 97 % for nested PCR, and 28 % and 60 % for GM test. These results suggesting that combined use of methods might improve the diagnosis of IA.

Aspergillus Bronchitis in Patients with Cystic Fibrosis

Aspergillus fumigatus frequently colonizes the airways of patients with cystic fibrosis (CF) and may cause various severe infections, such as bronchitis. Serological data, sputum dependent markers and longitudinal data of treated cases of Aspergillus bronchitis were evaluated for further description of this infection. This study, which comprises three substudies, aimed to analyze epidemiological data of Aspergillus in CF and the entity of Aspergillus bronchitis. In a first step, data of the German Cystic Fibrosis Registry were used to evaluate the frequency of Aspergillus colonization in patients with CF (n = 2599). Then a retrospective analysis of 10 cases of Aspergillus bronchitis was performed to evaluate longitudinal data for lung function and clinical presentation parameters: sputum production, cough and physical capacity. Finally, a prospective cohort study (n = 22) was conducted to investigate serological markers for Aspergillus bronchitis: total serum IgE, specific serum IgE, specific serum IgG, as well as sputum galactomannan, real-time PCR detection of Aspergillus DNA in sputum and fungal cultures. Analysis of the German CF registry revealed an Aspergillus colonization rate of 32.5% among the 2599 patients. A retrospective data analysis of 10 treated cases revealed the clinical course of Aspergillus bronchitis, including repeated positive sputum culture findings for A. fumigatus, no antibiotic treatment response, total serum IgE levels <200 kU/l, no observation of new pulmonary infiltrates and appropriate antifungal treatment response. Antifungal treatment durations of 4 ± 1.6 (2-6) weeks significantly reduced cough (P = 0.0067), sputum production (P < 0.0001) and lung function measures (P = 0.0358) but not physical capacity (P = 0.0794). From this retrospective study, a prevalence of 1.6% was calculated. In addition, two cases of Aspergillus bronchitis were identified in the prospective cohort study according to immunological, molecular and microbiological parameters. A prevalence of 9% was assessed. Aspergillus bronchitis appears to occur in a minority of colonized CF patients. Antifungal treatment may reduce respiratory symptoms and restore lung function.