Acute mastoiditis: clinical, microbiological, and therapeutic aspects.

The charts of 73 children (31 girls, 42 boys) aged 4 months to 14 years (mean 4.5 years) with acute mastoiditis managed during a 16-year period were reviewed. Of the patients 36% were less than 24 months old. Retro-auricular swelling was described in 63 of the 73 children, tenderness in 59, erythema in 58, and protrusion of the auricle in 45. A pathological tympanic membrane was noted in 33% of the patients and fever in only 29%. Apart from local inflammation, the most frequent complaints and symptoms were otalgia (n = 42), recent upper respiratory tract infections (n = 22), and fever alone (n = 22). A subperiosteal abscess was found in 36 patients, and CNS involvement in 5. Nearly half of the patients (48%) were on antibiotic therapy at admission. The isolation rates in bacterial cultures from subperiosteal aspirated (81%) and from mastoid mucosa (68%) were considerably higher than from blood cultures (14%) and were not influenced by previously administered antibiotics. Pneumococci (9/32) and Staphylococcus epidermidis (6/32) were the agents most often isolated. The incidence of the bacteria isolated from patients pre-treated with antibiotics differed from the incidence in patients not previously treated. In 24 patients (33%) the lesion healed with antibiotic therapy without mastoid surgery. Myringotomy and the insertion of a ventilation tube is indicated initially, if acute otitis media with effusion is found. In the absence of a subperiosteal abscess and of CNS involvement, a 48-hour trial of intravenous antibiotic therapy, directed also against staphylococci, is justified before mastoid surgery is considered.