Emergence of Streptococcus pneumoniae serotype 15A after the introduction of the conjugate vaccine in Victoria

Janet E Strachan, Stacey L Rowe, Eileen M Dunne and Geoffrey G Hogg
Med J Aust 2013; 199 (7): . || doi: 10.5694/mja13.10420
Published online: 7 October 2013

To the Editor: Streptococcus pneumoniae (the pneumococcus) is a major cause of severe bacterial disease worldwide. Since the introduction of the pneumococcal conjugate vaccine (PCV) there have been changes in the epidemiology of invasive pneumococcal disease (IPD), with an increase in infections with pneumococcal serotypes not included in the conjugate vaccines.1 The Microbiological Diagnostic Unit Public Health Laboratory at the University of Melbourne commenced pneumococcal serotyping in 1994. Before the PCV was included in the national immunisation schedule in 2005, a single isolate of S. pneumoniae serotype 15A, a non-vaccine serotype, had been detected in 1999 among Victorian invasive infections. The next serotype 15A invasive isolate was not seen until April 2009. The number of serotype 15A infections began increasing thereafter and accounted for 4% (13/295) of Victorian IPD from 1 January until 30 September 2012.

  • 1 Microbiological Diagnostic Unit Public Health Laboratory, University of Melbourne, Melbourne, VIC.
  • 2 Communicable Disease Epidemiology and Surveillance, Department of Health, Melbourne, VIC.
  • 3 Murdoch Childrens Research Institute, Melbourne, VIC.



We thank Victorian diagnostic laboratories for submitting isolates; staff of the Microbiological Diagnostic Unit for technical assistance; public health officers at the Victorian Department of Health for their contribution to IPD surveillance in Victoria; the Victorian Government’s Operational Infrastructure Support Program for the MLST work; and the Department of Health and Ageing for funding pneumococcal serotyping.

Competing interests:

No relevant disclosures.

  • 1. Miller E, Andrews NJ, Waight PA, et al. Herd immunity and serotype replacement 4 years after seven-valent pneumococcal conjugate vaccination in England and Wales: an observational cohort study. Lancet Infect Dis 2011; 11: 760-768.
  • 2. Fleming-Dutra K, Mbaeyi C, Link-Gelles R, et al. Streptococcus pneumoniae serotype 15A in psychiatric unit, Rhode Island, USA, 2010-2011. Emerg Infect Dis 2012; 18: 1889-1893.
  • 3. Gertz RE Jr, Li Z, Pimenta FC, et al. Increased penicillin nonsusceptibility of nonvaccine-serotype invasive pneumococci other than serotypes 19A and 6A in post-7-valent conjugate vaccine era. J Infect Dis 2010; 201: 770-775.
  • 4. Fenoll A, Aguilar L, Giménez MJ, et al. Variations in serotypes and susceptibility of adult non-invasive Streptococcus pneumoniae isolates between the periods before (May 2000-May 2001) and 10 years after (May 2010-May 2011) introduction of conjugate vaccines for child immunisation in Spain. Int J Antimicrob Agents 2012; 40: 18-23.
  • 5. Liu Z, Nachamkin I, Edelstein PH, et al. Serotype emergence and genotype distribution among macrolide-resistant invasive Streptococcus pneumoniae isolates in the postconjugate vaccine (PCV-7) era. Antimicrob Agents Chemother 2012; 56: 743-750.
  • 6. Dunne EM, Ong EK, Moser RJ, et al. Multilocus sequence typing of Streptococcus pneumoniae by use of mass spectrometry. J Clin Microbiol 2011; 49: 3756-3760.
  • 7. Hanage WP, Huang SS, Lipsitch M, et al. Diversity and antibiotic resistance among nonvaccine serotypes of Streptococcus pneumoniae carriage isolates in the post-heptavalent conjugate vaccine era. J Infect Dis 2007; 195: 347-352.


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