Decrease in Pneumococcal Otitis Media Cultures With Concomitant Increased Antibiotic Susceptibility in the Pneumococcal Conjugate Vaccines Era.

Objective: To study the change in the incidence and antibiotic susceptibility patterns of Streptococcus pneumoniae (Spn) in cultures obtained from children with otitis media (OM) during the pneumococcal conjugate vaccines (PCVs) era.

Study Design: Retrospective.

Setting: Secondary medical care center.

Patients: Children less than 8 years who presented with OM and had positive pneumococcal cultures during January 1, 2007 to December 12, 2014 were identified. Data recorded included demographics, preadmission antibiotics, culture source, and antibiotic susceptibility tests. We compared the pre-PCV years (2007-2008) with the transition years (2009-2011) and the post-PCV13 years (2012-2014).

Interventions: PCV7 (2009), PCV13 (2010), therapeutic.

Main Outcome Measure(s): Annual rate of Spn cultures, antibiotic susceptibility patterns.

Results: We identified 134 children (76 boys, 57%) who contributed 162 pneumococcal cultures. There was a downward trend in the annual incidence rate of Spn cultures between the pre-PCV years, transition years, and post-PCV13 years: 11.12, 8.48, and 4.11/1000 hospitalized children/year, respectively (p = 0.08, p = 0.04). Had there been no interventions, and based on the 2007 to 2009 average, the observed over the expected Spn cultures ratio rates for 2010 to 2014 were 0.59, 0.45, 0.40, 0.40, and 0.25, respectively. In parallel, the susceptibility of Spn strains to four commonly tested antibiotics significantly increased from the pre-PCV years to the transition years and the post-PCV13 years. In each period, Spn strains were penicillin sensitive in 37, 51, and 100%; for erythromycin, 46, 71, and 82%; for trimethoprim/sulfamethoxazole, 32, 71, and 97%; and for ceftriaxone, 95, 96, and 100%, respectively.

Conclusion: The introduction of PCVs significantly decreased the incidence rate of pneumococcal OM, and increased Spn susceptibility to common antibiotics.