The diagnosis of non-tuberculous mycobacteria (NTM) is a particular challenge in people with cystic fibrosis. Current standard diagnostic approaches rely on serial sputum culture, which is resource demanding, dependent on patient expectoration and may be compromised by excessive decontamination, conventional bacterial overgrowth and masking by concomitant oral and nebulised antibiotics. An alternative rapid, reliable and inexpensive diagnostic method is therefore urgently needed. Serum of patients withMycobacterium abscessusinfection and chronic suppurative lung disease without NTM infection was tested against an array of novel synthetic mycolic acids, identical or similar to natural components of mycobacterial cell walls, and glycopeptidolipid (GPL)-core antigen, which has previously been investigated inMycobacterium aviumpulmonary infection. Diagnostic accuracy of individual antigens and combination of various antigens were calculated. An ELISA using individual trehalose dimycolates and GPL-core antigen was able to effectively distinguish serum from infected and non-infected individuals with a specificity of 88% and a sensitivity of up to 88%, which increased to 88% sensitivity and 93% specificity by combining several antigens in the test. These results suggest synthetic mycolic acid antigens, used individually or in combination with GPL-core antigen could be successfully used to distinguish patients withM. abscessusinfection from disease controls.
Corresponding author's email: arf27@cam.ac.uk RATIONALE Numerous factors have been identified as contributing to the development of bronchiectasis although their relative prevalence remains poorly understood. The Cambridge Centre for Lung Infection (CCLI) at Papworth Hospital has one of the largest specialist bronchiectasis units in Europe. All new patients referred with recurrent or severe chest infections undergo a systematic investigation protocol to determine an underlying cause for their lung disease involving: high-resolution CT (HRCT) scan; full pulmonary function tests; sweat testing and CFTR sequencing; nasal nitric oxide measurements; immunological test including serum immunoglobulins, specific antibody levels pre-and post vaccination, auto-antibody screening; Aspergillus serology and multiple sputum sample testing for conventional and mycobacterial microscopy and culture. We undertook an analysis of the results of these investigations to determine the relative contributions of causal factors in patients with bronchiectasis. METHODS We examined the results and case notes of all 306 patients referred to the CCLI with recurrent chest infections between January 1st 2009 and December 31st 2010. Of these, 177 individuals had HRCT evidence of bronchiectasis. The results of their initial investigations were analysed to determine the proportion of patients we could ascribe a likely cause for their bronchiectasis and whether this affected their subsequent management. RESULTS. Using our investigation strategy, we were able to identify a likely cause in 121/177 (67%) patients, with 33% remaining idiopathic. Identifying an underlying cause frequently influenced subsequent patient management. Common causes included post-infection (24%), aspiration (8%), primary and secondary immune-deficiencies (5 and 6 % respectively), and allergic broncho-pulmonary aspergillosis (6%). Four new diagnoses of cystic fibrosis were made in patients aged 23, 26, 46 and 53. We also identified 3 new cases of Primary Ciliary Dyskinesia. CONCLUSION This study represents the largest analysis of causative factors of bronchiectasis to date. Using our current investigation algorithm, we can ascribe a cause for bronchiectasis in 67% of new patients. Many of the underlying conditions diagnosed require specialist management. This abstract is funded by: Wellcome Trust, Papworth Hospital NHS Foundation Trust Am J Respir Crit Care Med 185;2012:A3655 Internet address: www.atsjournals.org Online Abstracts Issue
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