Haemophilus influenzae and Haemophilus parainfluenza in CysticFibrosis: 15 Years Experience

Background: Haemophilus influenzae and Haemophilus parainfluenzae are commonly identified in the lower airways of patients with cystic fibrosis (CF). Little is known of the change in prevalence and antimicrobial susceptibility in this population over time. We examined the epidemiology of both organisms over 15 years in our CF clinic. Results: 1538 isolates from respiratory specimens of 349 CF patients over 15 years were investigated. Annual prevalence increased significantly for both bacteria, being more pronounced for H. parainfluenzae. Average percentage of resistant cultures increased by 46% (H. Influenzae) and 61% (H. Parainfluenzae). For H. influenzae, resistance to ampicillin was 34.4%, co-trimoxazole 21.4%. For H. parainfluenzae, resistance to ampicillin was 50.0%, co-trimoxazole 26.8%. Resistance in H. influenzae and H. parainfluenzae to ampicillin and in H. parainfluenzae to amoxicillin/ clavulanic acid and co-trimoxazole increased over the study. Conclusion: This present study has shown an increased annual prevalence of H. influenzae and H. parainfluenzae in a large group of CF patients. Resistance to ampicillin significantly increased for H. influenzae and H. parainfluenzae, but increased resistance to amoxicillin/ clavulanic acid and co-trimoxazole was only significant in H. parainfluenzae.