P-456. Acute Mastoiditis in Children in the era of Pneumococcal Conjugate Vaccines

Abstract Background Acute mastoiditis (AM) is a complication of otitis media. The most common cause is Streptococcus pneumoniae. The incidence of invasive pneumococcal infections has decreased following the introduction of PCV-7 in 2000 and PCV-13 in 2010. We evaluated the changes in the incidence, bacteriology and complications of AM following introduction of PCV-7 and PCV-13. Methods A retrospective review of medical records during 19-year period (2000-2018). AM was defined as a suppurative infection of mastoid air cells with symptoms of less than 3 weeks. Results We identified 242 children with AM: 138 in the first period (2000 to 2010): PCV-7 and 104 in the second period (2011 to 2018): PCV-13. No significant change in AM incidence was noted: 11.0 cases/10,000 admissions in the first period and 8 cases/10,000 admissions in the second (p=0.31). Ages ranged from 3 months to 18 years (median 5.6 years). Symptoms included fever (52%), ear pain (63.6%) and mastoid tenderness (64.9%). Prior antibiotics were prescribed to 37.6%. Surgery was performed on 52.1%. Cultures from 125 patients showed S. pneumoniae (29.6%), S. pyogenes (17.6%), P. aeruginosa (16.8%), S. aureus (13.6%). Two had complicated AM due to Fusobacterium necrophorum. During the second period, S. pneumoniae was detected on 14/46 (34.8%) compared to 21/79 (21.1%) in the first (p=0.417). Partial or complete PCV vaccination was documented in 89 patients including 13/37 who had S. pneumoniae culture-positive AM. Most common parenteral antibiotics used were: IV ceftriaxone (64.5%), IV clindamycin (42.1%), IV ampicillin/sulbactam (19.8%). Most common oral antibiotics: amoxicillin-clavulanate (38%), clindamycin (20.2%) and amoxicillin (8.3%). Complications included bony erosive changes (mastoid/temporal bone) in 78, soft tissue abscesses in 39, venous sinus thrombosis in 10, facial nerve palsy in 6, intracranial extension in 7 patients, 6 of which in the second period. Conclusion Despite a decrease of invasive pneumococcal infections post PCV-7, the incidence of AM in our pediatric population remained unchanged after PCV-13 introduction with many complications. The role of the updated pneumococcal conjugate vaccines on AM incidence needs further evaluation. Disclosures All Authors: No reported disclosures