P3 ECBS study: exacerbation of chronic bronchial sepsis – utility of a novel rapid molecular diagnostic test (MBLA) to detect and quantify viable bacteria. (11th November 2022)

• Record Type: Journal Article
• Authors: Dhasmana, DJ; Walbaum, N; Finch, S; Sloan, DJ; Gillespie, SH; Sabiiti, W
• Is Part Of: Thorax. Volume 77(2022)Supplement 1
• Page Start: A82
• Page End: A82
• Publication Date: 2022-11-11
• Subjects: Chest -- Diseases -- Periodicals; Thorax; Chest -- Diseases; Periodicals; Periodicals; 617.54
• DOI: 10.1136/thorax-2022-BTSabstracts.139
• Languages: English
• ISSNs: 0040-6376

Abstract

Abstract : Introduction and Objectives: The significant overlap of clinical features of patients with bronchiectasis and those with COPD and frequent infections has led to the term 'chronic bronchial sepsis' (CBS). Culture-dependent techniques lack sensitivity, are time-consuming and rarely helpful in acute exacerbations. We have developed a novel rapid sputum diagnostic test, the molecular bacterial load assay (MBLA), a ribosomal RNA-based qPCR assay able to provide both diagnostic and quantitative data on viable bacteria. After successful lab development, we sought to provide proof-of-concept data for the CBS-MBLA in clinical practice. Methods: The Exacerbation of CBS (ECBS) study is a prospective observational study of patients with a history of CBS (confirmed bronchiectasis or COPD with positive sputum bacteriology) presenting to hospital with acute severe exacerbation. Sputum was processed alongside standard care. The CBS-MBLA identifies commonly identified bacteria in CBS: P.aeruginosa, H.influenzae, S.pneumoniae, S.aureus, M.catarrhalis, K.pneumoniae . The primary outcome was MBLA performance compared to sputum culture. Secondary outcomes included longitudinal assessment of bacterial loads over time and quality of life (QoL). Results: 26 patients with 29 exacerbation-admissions were enrolled and tracked over 8-months with the following baseline features: median age 72 (49–89); 1.9 female:1 male; COPD 59%, bronchiectasis 41%; ever-smokers 68%; BMI 21.9kg/m 2 (13.8–36.7); CAT score 30 (5–40); inhaled steroids 26%; admission blood results CRP 52 g/l (1.6–210.3), neutrophils 8.8 x 10 9 (2.9–20.5). Compared to culture, CBS-MBLA showed higher diagnostic yields from day 1 sputum (14/27 (52%) vs 10/27 (37%)) and when all day 1–3 sputum was included (24/27 (89%) vs 12/29 (41%)). H.influenzae (17) and P.aeruginosa (12) were the most commonly identified bacteria by MBLA. Of 3 negative MBLA results, 1 cultured S.pseudopneumoniae and 2 remained culture-negative. MBLA-bacterial loads did not consistently fall during clinical recovery, either between different patient-pathways or within the same patient ( figure 1 ). High QoL scores at presentation reduced significantly with treatment, however, the sample size precluded sufficient correlation with MBLA values. Conclusions: We have shown proof-of-concept of the CBS-MBLA in clinical practice in acute exacerbations. We show 89% sensitivity despite antibiotic use and consistent performance on quantitative viable bacterial loads. CBS-MBLA offers significant potential value in clinical practice and in our understanding of CBS.