S121 Sputum bacterial pathogens and antibiotic resistance patterns among asthma patients in Oxfordshire: A 27-year longitudinal study

<h3>Background</h3> The respiratory microbiome is increasingly recognised as a treatable trait in asthma, due to its impacts on respiratory function and exacerbations. Antimicrobial resistance in asthma causes challenges in managing infections and appropriate treatment. <h3>Methods</h3> We analysed bacterial pathogens in sputum cultures among patients with a primary diagnosis of asthma over a 27-year period. 1348 asthma patients, 7279 sputum bacterial pathogens tests, and 86567 antibiotic resistance tests were analysed from the Infections in Oxfordshire Research Database (IORD) from 1993 to 2019. <h3>Results</h3> A potentially pathogenic bacterial species was identified in 24.2% of asthma patients at any time point, including <i>Haemophilus influenzae</i> (8.8%), <i>Pseudomonas aeruginosa</i> (8.3%), and <i>Staphylococcus aureus</i> (2.9%). From 1993 to 2019, the proportion of all the bacterial isolates accounted for by <i>P. aeruginosa</i> increased (6.3% to 26.0%), while those due to <i>M.</i> catarrhalis (31.2% to 6.0%) decreased. Antimicrobial resistance throughout this period fluctuated, with an average resistance prevalence to any antibiotic agent of 12.3% (12.1%-12.5%). The highest resistance rates were observed for macrolides (27.0% (25.9%-28.1%)) and penicillins (21.3% (20.7%-21.9%)). The rate of antimicrobial resistance increased from 5.3% in 1993, peaked at 27.5% in 2011 and decreased to 6.9% in 2019. Resistance rate for macrolides (1.2% to 36.8%) and tetracyclines (1.2% to 34.1%) continued to increase from 1993 to 2019. For <i>H. Influenzae</i>, 25.0% of the samples were resistant to macrolides and the resistance rate for penicillins increased from 12.3% in 1993 to 24.1% in 2019. 25.0% of the <i>P. aeruginosa</i> samples were resistant to fluoroquinolones and 56.0% of <i>S. aureus</i> samples were resistant to penicillins. Patients with an identified bacteria were associated with hospital admission and patients who were resistant to antibiotics were associated with staying in the hospital longer. For patients admitted to the hospital for over 10 days, the antibiotic-resistant rate was 16.4% compared to 9.9% among asthma outpatients. <h3>Conclusion</h3> 24.2% of asthma patients had positive sputum samples, most commonly with <i>H. influenzae</i>, with increasing evidence of resistance to macrolides and penicillins over a 27-year longitudinal study.