Scientific Publications
P187 Diversity of pseudomonas aeruginosa in non-cystic fibrosis bronchiectasis: insights from a norfolk patient population
Thorax, 80, A258
Background Bronchiectasis is a chronic pulmonary condition characterised by abnormal, irreversible bronchial dilation, leading to persistent airway infection and inflammation. Pseudomonas aeruginosa colonisation is associated with frequent exacerbations and higher mortality. Previous sequencing studies have shown significant diversity between patients in P. aeruginosa sequence types. Methods Adults with non-CF bronchiectasis and at least 1 positive P. aeruginosa sputum culture over 12 months were recruited between January and December 2024. Bacteria were cultured from sputum using differential agar and some incubated in 5% CO2 to reflect the lung microenvironment. DNA from isolates was sequenced using Illumina NextSeq. A core SNP phylogeny was constructed to assess intra-patient strain diversity. Antibiotic minimum inhibitory concentration testing was performed on agar plates to determine the AMR profile, using EUCAST breakpoints. Existing wastewater-derived phages were screened for host range against clinical isolates. Results 541 suspected P. aeruginosa isolates were cultured from 49 participants. Of the isolates tested thus far, 73% were confirmed as P. aeruginosa using whole genome sequencing. P. aeruginosa was still detected in some patients post-antibiotic treatment. Phylogenetic analysis revealed patient-specific clades, as well as notable cross-patient clustering. 69% of tested isolates were resistant to ciprofloxacin; one isolate was resistant to all frontline antibiotics used at the host institution. Notably, none of the 14 previously isolated phages lysed clinical strains, despite demonstrating activity against other clinical and reference strains. Conclusions Clinical P. aeruginosa isolates from bronchiectasis patients in Norfolk display significant in vitro antibiotic resistance and patient-specific genetic diversity. These results are in keeping with or slightly higher than in previous studies which show greater diversity between patients than within individual patients. Previously isolated phages failed to lyse these strains, highlighting the need for a more targeted isolation approach to identify therapeutically viable phages for bronchiectasis patients.
Thorax, 80, A258
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