Monitoring early antibiotic treatment with anti-Pseudomonas aeruginosa serology: a comparison of two specific antibody panels.

Abstract

Background: Pseudomonas aeruginosa chronic infection can cause lung function decline in people with cystic fibrosis, and early antibiotic treatment (EAT) is crucial to prevent it. While culture methods are standard for monitoring treatment efficacy, serology may be a complementary tool. The primary objective of this study was to evaluate the accuracy of two commercially available tests in measuring the immune response to P. aeruginosa antigens in people with cystic fibrosis who had undergone EAT.

Methods: Two commercially available ELISA panels, CF-St-Ag or AP, ELA and ExoA antigens, were used to assess immune responses at initial P. aeruginosa detection and 12 months after EAT. Receiver operating characteristic curves were used to determine the optimal antibody titre cut-off for detecting P. aeruginosa infection.

Results: Over 14 years, 170 episodes of initial P. aeruginosa infection in 134 modulator-naïve people with cystic fibrosis (median age 11.2 years) were treated with early eradication treatment, achieving a 77.1 % sustained eradication rate. Of 333 sera samples, titres ExoA showed a sensitivity of 76.9 %, specificity of 95.8 %, and a negative predictive value of 85 %. At 12 months, successful EAT resulted in significantly lower antibody titres compared to treatment failure (p < 0.05). A statistically significant association between any anti-P. aeruginosa antibody titre and microbiological outcome was observed for all antigens tested.

Conclusions: No significant differences were observed when comparing the performance of the two kits. Serology is a useful adjunct test for monitoring the effectiveness of EAT against initial P. aeruginosa infection and appropriate antibody titre cut-offs should be used in the early stages of P. aeruginosa infection.