Daijiworld Media Network – Western Pennsylvania
Western Pennsylvania, Jul 21: Haemophilus influenzae has emerged as the most common bacterial cause of acute ear infections in young children, according to a new study that also found a high prevalence of antibiotic-resistant strains, highlighting the need for continued monitoring and improved treatment strategies.
The prospective cohort study, conducted in Western Pennsylvania, enrolled 451 children aged between six and 35 months from October 2019 to August 2023. Researchers examined bacterial patterns in children diagnosed with acute otitis media (middle ear infection) and upper respiratory infections.

Middle ear fluid samples were obtained through tympanocentesis from 57 children with acute otitis media and tested for three common bacterial pathogens – Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis. Nasal specimens were collected from all participants.
Researchers found that a single bacterial pathogen was identified in 79 per cent of the middle ear fluid samples. H. influenzae was detected in 56 per cent of the samples, making it the most frequently identified pathogen, followed by M. catarrhalis (23 per cent) and S. pneumoniae (21 per cent).
The study also found only modest agreement between bacteria present in nasal swabs and those detected in middle ear fluid, suggesting that nasal colonisation may not accurately predict the organism causing the ear infection.
Among children with acute otitis media, nasal testing detected S. pneumoniae in 46 per cent, H. influenzae in 43 per cent and M. catarrhalis in 70 per cent of cases.
Most S. pneumoniae isolates remained susceptible to penicillin, with commonly detected serotypes including 3, 15B, 15C, 23A, 23B/B1 and 35B. In contrast, nearly 40 per cent of children carrying H. influenzae harboured β-lactamase-producing strains, which are resistant to several commonly used antibiotics.
The researchers said the findings point to changing bacterial patterns in childhood ear infections and emphasised the importance of ongoing surveillance of disease-causing bacteria and antibiotic resistance to guide treatment decisions and support future vaccine development.