Surveillance of children with acute otitis media (AOM) for nasopharyngeal colonization with Streptococcus pneumoniae before, during and after the introduction of 7-valent pneumococcal conjugate vaccine (PCV7) indicated the near-complete elimination of PCV7 strains and the emergence of pneumococcal serotype 19A.
To determine effects of the introduction of 13-valent pneumococcal conjugate vaccine (PCV13) on pneumococcal nasopharyngeal colonization, we obtained nasopharyngeal cultures from 228 children 6 through 23 of age months presenting with a new episode of AOM during 2012 and 2013 and enrolled in an ongoing clinical trial of antimicrobial efficacy. All children had received at least 2 doses of PCV13. The S. pneumoniae isolates were subjected to serotyping and testing for antimicrobial susceptibility. We compared the findings with results obtained in 3 earlier studies.
We found nasopharyngeal colonization with S. pneumoniae in 113 (50%) of the children with AOM. PCV7 and PCV13 serotypes accounted for 2% and 12%, respectively, of the pneumococcal isolates. Of the 14 PCV13 isolates, 8 were serotype 19A. Nonvaccine serotypes accounted for 69% of the isolates. Most frequently occurring were subtypes of serotype 15 (23%) and serotype 35B (9%). Overall, 33% of the isolates were penicillin nonsusceptible, a proportion not significantly different from proportions found in our 3 earlier studies (26%, 36% and 37%, respectively). Serotypes 15 and 35B accounted for 51% of penicillin-nonsusceptible isolates.
Expansion of contents of pneumococcal vaccine administered to children is followed by not-fully-predictable changes in nasopharyngeal pneumococcal colonization. Continued surveillance is required to help inform future vaccine development.
From the *Department of Pediatrics, University of Pittsburgh School of Medicine and Children’s Hospital of Pittsburgh, Divisions of General Academic Pediatrics and Infectious Disease, University of Pittsburgh, Pittsburgh, PA; and †Kentucky Pediatric Research Inc., Bardstown, KY.
Accepted for publication May 26, 2014.
Funding for the parent study, A Phase III, Multicenter, Randomized, Double Blind, Placebo-Controlled Clinical Trial to Evaluate the Efficacy of Short-Course Antimicrobial Therapy for Young Children with Acute Otitis Media (AOM) and Impact on Antimicrobial Resistance, was received from the National Institute of Allergy and Infectious Diseases grant number 10-0083. ClinicalTrials.gov Identifier: NCT01511107. This work was also supported by NIH/NCRR/CTSA (UL1RR024153, University of Pittsburgh Clinical and Translational Science Institute [CTSI]).
Address for correspondence: Judith M. Martin, MD, Children’s Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Division of General Academic Pediatrics, 3414 5th Ave, CHOB 3rd Floor, Room 305, Pittsburgh, PA 15213. E-mail: email@example.com.