Nasopharyngeal cultures in children with AOM – A retrospective study on bacteriological findings and impact on management

Background: Despite a far from perfect correlation with middle ear growth, nasopharyngeal cultures are sometimes used in children with acute otitis media (AOM) in order to have some idea of the causative pathogen. How these cultures are used in clinical practice and to what extent they influence clinical management has not previously been studied. The objective with this study was to investigate in what circumstances nasopharyngeal cultures are performed in children with AOM, what the bacteriological results are and to what extent cultures influence clinical management. Methods: All nasopharyngeal cultures taken in clinical practice from children with AOM in the county of Skåne, Sweden, during 2017–2018 were retrieved together with details from the medical charts two months prior to and one month after the culture. Information about the reason for culturing, the bacteriological result, and whether this result changed the management of the child, was retrieved from the charts. Results: During the 2 years, 978 nasopharyngeal cultures were taken in children with AOM. The most common reasons for obtaining a culture was a recurrence of AOM (40%) or treatment failure (22%). Many of the children had ongoing or recent antibiotic treatment. M. catarrhalis was the most commonly identified pathogen (53%), followed by H. influenzae (30%) and S. pneumoniae (14%). Resistance rates were low, and the most commonly identified resistant pathogen was betalactamase-negative ampicillin-resistant H. influenzae. One in five cultures led to a change in management, such as a change of antibiotics or an additional check-up. This was most commonly seen in association with H. influenzae, reflecting clinical practice in Sweden, where AOM is primarily treated with penicillin V. Conclusion: Despite not having a perfect correlation with middle ear growth, nasopharyngeal cultures can provide clues about suitable alternative antibiotics in cases of treatment failure, and they can help monitoring nasopharyngeal carriage and resistance rates.