Epidemiology and Infection

Original Papers

Vaccines

Laboratory surveillance of invasive pneumococcal disease in New South Wales, Australia, before and after introduction of 7-valent conjugate vaccine: reduced disease, but not antibiotic resistance rates

S. OFTADEHa1 c1, H. F. GIDDINGa1a2 and G. L. GILBERTa1a3

a1 Centre for Infectious Diseases and Microbiology – Public Health, Westmead Hospital, Westmead, NSW, Australia

a2 School of Public Health and Community Medicine, University of New South Wales, Sydney, Australia

a3 Sydney Institute for Emerging Infections and Biosecurity, University of Sydney, NSW, Australia

SUMMARY

We compared serotype distributions of Streptococcus pneumoniae isolates from patients aged <5 and ≥5 years with invasive pneumococcal disease in New South Wales, Australia, and antibiotic susceptibilities of isolates from the <5 years age group only, before (2002–2004) and after (2005–2009) introduction of the 7-valent pneumococcal conjugate vaccine (PCV7). Overall, there were significant decreases in the mean annual number of referred isolates (770 vs. 515) and the proportion belonging to PCV7 serotypes (74% vs. 38%), but non-PCV7 serotypes, particularly 19A, increased (5% vs. 18%). All changes were more marked in the <5 years age group. Susceptibility testing of isolates from the <5 years age group showed variation in resistance between serotypes, but significant overall increases in penicillin non-susceptibility (23% vs. 31%), ceftriaxone resistance (2% vs. 12%) and multidrug resistance (4% vs. 7%) rates; erythromycin resistance fell (32% vs. 25%). Continued surveillance is needed to monitor changes following the introduction of 13-valent PCV in 2012.

(Received June 11 2012)

(Revised August 03 2012)

(Accepted August 29 2012)

(Online publication September 25 2012)

Key words

  • Antibiotic susceptibility;
  • broth microdilution;
  • serotype distribution;
  • 7-valent pneumococcal conjugate vaccine;
  • Streptococcus pneumoniae

Correspondence

c1 Author for correspondence: Dr S. Oftadeh, Centre for Infectious Diseases and Microbiology – Public Health (CIDM), Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, Darcy Road, Westmead, New South Wales, 2145 Australia. (Email: shahin.oftadeh@swahs.health.nsw.gov.au)

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