Development of rapid tools for the early diagnosis of Pseudomonas aeruginosa pulmonary infection in patients with cystic fibrosis

• Main Author: Weisner, Abbie Michelle
• Published: Imperial College London 2008
• Subjects: 616.9
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491101

Pseudomonas aernginosa causes chronic lung infections in patients with cystic fibrosis (CF) and is associated with a marked decline in clinical status. Early detection ofthe organism and aggressive specific antibiotic treatment is beneficial to the patient and delays the onset ofchronic infection. The detection ofserum antibodies to P. aernginosa has been reported utilising a wide range ofantigens. The first part ofthis study used SDS-PAGE and immunoblotting to investigate protein and lipopolysaccharide (LPS) antigens from reference and clinical strains and the CF senun antibody response to them. The A-band LPS species, which was not serotype-specific, was studied further and its prevalence determined. It was found to be highly specific for P. aeruginosa, common to approximately 90 % ofclinical strains tested and provoked a strong antibody response. Serum and non-invasive samples (oral fluid, sputum and urine) from CF patients, patients with primary ciliary dyskinesia and healthy volunteers were analysed for A-band LPS-specific antibodies using SDS-PAGE and immunoblotting. Both oral fluid and sputwu showed excellent correlation with senun for antibodies to A-band. Since Pseudomonas-specific antibodies were found in healthy volunteer samples, it was necessary to develop a quantitative ELISA. Both IgM and IgG-specific assays were optimised. The serwn antibody response was further assessed by comparison to culture ofP. aernginosa from sputum, conversion ofP. aernginosa to the mucoid phenotype and lung function data. The IgG-specific assay clearly distinguished clinical infection, although no patients were shown to seroconvert prior to growth ofthe organism from sputum. IgM-specific antibody levels were significantly associated with positive sputum culture, in 83 % ofpatients. Finally, the IgG-specific assay was compared to the current in-house ELISA and two commercial products. There was moderate correlation between the developed assay, the in-house assay and one ofthe commercial kits.