Emergence of Streptococcus pneumoniae Serogroups 15 and 35 in Nasopharyngeal Cultures from Young Children with Acute Otitis Media

Pediatr Infect Dis J. 2014 Jun 6. [Epub ahead of print]

Emergence of Streptococcus pneumoniae Serogroups 15 and 35 in Nasopharyngeal Cultures from Young Children with Acute Otitis Media.

Martin JM1, Hoberman A, Paradise JL, Barbadora KA, Shaikh N, Bhatnagar S, Shope T, Block SL, Haralam MA, Kurs-Lasky M, Colborn DK, Green M.

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Abstract

BACKGROUND::

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.

METHODS::

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 three earlier studies.

RESULTS::

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 three earlier studies (26%, 36%, and 37%, respectively). Serotypes 15 and 35B accounted for 51% of penicillin-nonsusceptible isolates.

CONCLUSION::

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.

PMID: 24911895 [PubMed - as supplied by publisher]