Background: The microbiology of acute otitis media has changed in the heptavalent pneumococcal conjugate vaccine (PCV) era. We hypothesize similar changes with pediatric mastoiditis.
Objectives: To compare the etiology of mastoiditis in the pre-PCV (January 1995-December 2000) and post-PCV (January 2001- April 2005) eras to guide empiric antimicrobial therapy in the pediatric emergency department.
Methods: Retrospective chart review of all patients admitted with a diagnosis of mastoiditis from January 1995 to April 2005.
Results: One hundred twenty-two charts were reviewed, 68 pre-PCV and 54 post-PCV. Etiological agents were determined by culture results in 60 patients. The most common bacterial isolates were Streptococcus pneumoniae (24), Pseudomonas aeruginosa (12), Staphylococcus aureus (12), Streptococcus pyogenes (8), and Haemophilus influenzae (2). There was no reduction in mastoiditis due to S. pneumoniae from the pre-PCV to the post-PCV eras (odds ratio [OR], 0.9; 95% confidence interval [CI], 0.4-2.1; P = 0.77). Ceftriaxone nonsusceptibility was seen in 30% of post-PCV S. pneumoniae isolates compared with 7% of pre-PCV isolates. Acute mastoiditis was diagnosed in 93 patients, and chronic mastoiditis (defined as ≥3 wk of symptoms) was diagnosed in 29 patients. Streptococcus pneumoniae was more likely to be implicated in acute versus chronic mastoiditis (OR, 9.2; 95% CI, 1.2-52.2; P = 0.01). Pseudomonas aeruginosa was more frequently implicated in chronic versus acute mastoiditis (OR, 16.4; 95% CI, 2.1-75.8; P = 0.0003).
Conclusions: There was no difference in the proportion of pediatric mastoiditis cases caused by S. pneumoniae in the pre-PCV versus post-PCV eras. Empiric antimicrobial therapy with ceftriaxone alone is not sufficient in the post-PCV era.