Comparative characteristics of the clinical course of non-invasive haemophilus influenzae infection caused by type B and non-typeable strains in hospitalized children

Aim: To clinically characterize non-invasive forms of Haemophilus influenzae infection caused by type b (Hib) and non-typeable strains (NTHi) strains in children. Materials and methods : We analyzed medical records of children hospitalized at Children’s City Clinical Hospital No. 5 named after N.F. Filatov (Saint Petersburg) from 2002 to 2023. The study included 62 patients (aged 1 month to 16 years) with verified non-invasive forms of H.influenzae infection: 25 children with Hib infection and 37 with NTHi infection. Verification was performed using bacteriological methods (cultures of nasopharyngeal mucus, sputum, and discharge from ENT foci). Results : In some patients, the process was limited to acute respiratory infection (Hib: 8%; NTHi: 21%). Pneumonia subsequently developed (Hib: 32%; NTHi: 30%) or purulent ENT foci (Hib: 60%; NTHi: 49%). Pneumonia predominantly affected children under 24 months (79%), regardless of etiology; acute respiratory failure of grades I–III was recorded in 84% of patients with pneumonia. Among ENT focal infections, pansinusitis predominated (42%); mastoiditis and otoantritis were identified in 2 cases of Hib infection. Most patients (76%) with ENT involvement were hospitalized between days 7 and 21 of illness. No significant age differences were found between the Hib and NTHi groups. Prehospital targeted therapy was administered to 10 of 62 children; penicillins were ineffective in most cases, whereas II-III generation cephalosporins were effective. Conclusion: Forms of H.influenzae infection caused by Hib and NTHi are characterized by similar manifestations, an indolent course with moderate systemic toxicity, and involvement of young children. Late presentation and diagnosis, along with inadequate prehospital antibiotic therapy, lead to severe disease progression and risk of progression to invasive disease.