Clinical relevance of bacterial resistance in lower respiratory tract infection in primary care: Secondary analysis of a multicentre European trial

Background: The impact of antimicrobial resistance on clinical outcomes in patients with lower respiratory tract infection in primary care is largely unknown. Aim:We determined the illness course of infections with resistant bacteria in adults presenting with acute cough to primary care. Design and setting:Secondary analysis of a multicentre European trial in primary care.Method: 2,061 adults with acute cough (≤ 28 days) were recruited from primary care and randomised to amoxicillin or placebo. To reflect the natural course of disease, only patients in the placebo group (n = 1,021) were eligible. Nasopharyngeal flocked swabs and/or sputa (when available) were analysed at baseline and Streptococcus pneumoniae and Haemophilus influenzae isolates underwent susceptibility testing. Patients recorded their symptoms in a diary every day for four weeks. Patients with and without resistant bacterial infection were compared with regards to symptom severity, duration of symptoms and a return consultation. Results: Of the 834 patients with diary records, 104 showed S. pneumoniae and/or H. influenzae infection. Of this number, 54/104 (52%) were antibiotic-resistant, while 7/104 (7%) were resistant to penicillin. Neither duration of symptoms rated “moderately bad or worse” (hazard ratio 1.27, 95% CI 0.67-2.44) nor mean symptom severity (difference -0.48, 95% CI -1.17-0.21) nor worsening of illness (odds ratio 0.31, 95% CI 0.07-1.41) differed significantly between the antibiotic resistant and antibiotic sensitive groups. Conclusion: The illness course of antibiotic-resistant lower respiratory tract infection does not differ from that caused by sensitive bacteria