Introduction Bacterial infections are a well-known trigger for exacerbations of COPD. A variety of antibiotics are regularly prescribed for this group of patients but the risk and frequency of antibiotic resistance in the COPD population is less understood. Routine culture data can be evaluated to establish resistance prevalence and patterns.
Methods Culture data were collected from the sputum samples of 293 patients in the London COPD cohort over a period of 5 years (01/01/2006–31/12/2010) mean (±SD) months in study 28.4(±19.9); age 69.9 years (±8.9); predicted FEV1 47.8% (±16.5); male gender 58%; exacerbation samples 48.9%; sputum producers 77.5%. Identification of bacterial presence was established and where clinically indicated drug sensitivity tests (DSTs) were performed. A resistant sample was reported as any bacterial isolate resistant to at least one antimicrobial agent.
Results 92/293 (31.4%) patients had at least one bacteria positive sample over the study period. 87/92 (94.6%) patients had samples where DSTs were performed on bacteria positive samples. Resistance was observed in 69/87 (79.3%) patients. 30/293 (10.2%) patients were resistant to all samples where DSTs were performed. 227/293 (77.5%) of patients were sputum producers. There was no significant relationship between predicted FEV1 and antibiotic resistance frequency in this cohort (X2-test; p=0.577). Patients who were classified as regular sputum producers were more likely to exhibit resistance in culture positive bacteria (p=0.048).
Conclusion Results from this analysis conclude that an estimated 23.5% of COPD patients will develop resistance to an antimicrobial agent within 28.4 months of follow-up with sputum producers being at a higher risk. This study highlights the importance of investigating sputum samples with determination of resistance patterns. Information on resistance patterns and transmission of resistance in COPD can allow more appropriate and targeted antibiotic therapy for COPD exacerbations with improved outcomes.