Bacteriology in relation to clinical findings and treatment of acute mastoiditis in children.

Objective: We assessed clinical, radiological, laboratory and microbiological findings in children with acute mastoiditis in order to improve the diagnostics and treatment of these patients. We also investigated whether different pathogens cause different clinical findings of mastoiditis.
Methods: A retrospective review of the medical records of all children aged 0-16 years treated as in-ward patients for acute mastoiditis at Helsinki University Central Hospital, Department of Otorhinolaryngology, between 2003 and 2012.
Results: Fifty-six patients met the inclusion criteria. The incidence of mastoiditis was 1.88/100000/year. The most common pathogens were Streptococcus pneumoniae (38%), Streptococcus pyogenes (11%) and Pseudomonas aeruginosa (11%). Of S. pneumoniae, 48% had reduced susceptibility (intermediate or resistant) for the common antimicrobials; this was clearly overrepresented relative to the background population (p<0.001). Otalgia and retroauricular symptoms were common in the patients with S. pneumoniae. Otorrhoea was less common (p=0.03) in these patients relative to the other pathogens. Patients with S. pneumoniae had more destruction of the mastoid septa (p=0.05) than patients with any of the other pathogens. Mastoidectomy was performed in 34% of all cases, it was most common (60%) in the patients with S. pneumoniae with reduced susceptibility. The patients with S. pyogenes had less otalgia and seemed to have less retroauricular symptoms relative to other pathogens. P. aeruginosa especially affected children with tympanostomy tubes, caused otorrhoea in all patients and caused a milder form of disease with less retroauricular swelling (p=0.04) than the other pathogens, and there was no need for mastoidectomies. The younger children (<2 years) had less otorrhoea and more retroauricular symptoms of infection than the older patients. No significant differences emerged in outcome of the patient groups.
Conclusions: The clinical findings of acute mastoiditis differ according to the causative pathogen. S. pneumoniae, especially strains with reduced susceptibility, causes severe symptoms and leads to mastoidectomy more often than the other pathogens. S. pyogenes causes less otalgia than the other pathogens. P. aeruginosa particularly affects children with tympanostomy tubes and causes a less aggressive form of disease.
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