OBJECTIVES: Since the introduction of PCV-10 in 2011 there is a lack of evidence about its impact on acute otitis media (AOM) in children under five years in Colombia. We aimed to describe the clinical and sociodemographic characteristics of patients from 3 to 59 months old with diagnosis of AOM whom attended to a third-level health institution from Cartagena, Colombia. We estimated the prevalence of AOM caused by S. pneumoniae, the serotype distribution and antimicrobial resistance patterns.

METHODS: A prospective cohort study was conducted during 12 months from August 5th 2022 to August 5th, 2023. Diagnosis of AOM was confirmed by an otorhinolaryngologist. Middle ear fluid (MEF) samples were collected using a swab or by tympanocentesis depending on if spontaneous drainage was present. Samples with a positive culture for S. pneumoniae were sent to the National Health Institute for serotyping.

RESULTS: A total of 61 patients were enrolled. 58% were male, the median age was 12 months. Most frequent isolates were P. aeruginosa (14.8%), S. pneumoniae and Methicillin-resistant S. aureus 9,8% each. Six cases of S. pneumoniae were identified, median age was 24 months, none had any comorbidities, only one presents previous episodes of AOM. 5 of these were vaccinated. The serotypes distribution was 19A 4 (67%), 10F and 35A 1 (17%) each; the six isolates showed antimicrobial resistance, with 19A being multidrug-resistant to beta-lactam, macrolides, lincosamides and TMP/SMX.

CONCLUSIONS: S. pneumoniae remains a leading cause of AOM, even though its incidence has decreased over time, particularly for cases linked to the PCV-10 vaccine serotypes. Serotype 19A accounts for 67% of these infections and exhibits a multidrug-resistant pattern, like the behavior observed in invasive pneumococcal diseases. Future studies will be needed to track AOM trend after PCV13 introduction.