Group A streptococci (GAS) and other β-hemolytic streptococci (BHS) cause pharyngitis, severe invasive disease and serious nonsuppurative sequelae including rheumatic heart disease and post streptococcal glomerulonephritis. The aim of this study was to assess carriage rates and anti-streptococcal C5a peptidase (anti-SCP) IgG levels and identify epidemiologic factors related to carriage or seropositivity in Australian children.
A throat swab and blood sample were collected for microbiological and serological analysis (anti-SCP IgG) in 542 healthy children aged 0–10 years. Sequence analysis of the SCP gene was performed. Serological analysis used a competitive Luminex Immunoassay designed to preferentially detect functional antibody.
GAS-positive culture prevalence in throat swabs was 5.0% (range 0–10%), with the highest rate in 5 and 9 years old children. The rate of non-GAS BHS carriage was low (<1%). The scp gene was present in all 22 isolates evaluated. As age of child increased, the rate of carriage increased; odds ratio, 1.14 (1.00, 1.29); P = 0.50. Geometric mean anti-SCP titers increased with each age-band from 2 to 7 years, then plateaued. Age, geographic location and number of children within the household were significantly associated with the presence of anti-SCP antibodies.
Children are exposed to GAS and other BHS at a young age, which is important for determining the target age for vaccination to protect before the period of risk.
From the *Vaccinology and Immunology Research Trials Unit, Women’s and Children’s Hospital, †School of Paediatrics and Reproductive Health, ‡Robinson Research Institute, University of Adelaide, North Adelaide, South Australia, Australia; §School of Paediatrics and Child Health, University of Western Australia, ¶Vaccine Trials Group, Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, Subiaco, Western Australia, Australia; ‖Queensland Paediatric Infectious Diseases Laboratory, Queensland Children’s Medical Research Institute, **Royal Children’s Hospital, University of Queensland, Herston, Brisbane, Queensland, Australia; ††National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases, The Children’s Hospital at Westmead, Westmead, ‡‡Marie Bashir Institute, The University of Sydney, Sydney, New South Wales, Australia; §§Department of Paediatrics and Child Health, ANU Medical School, The Canberra Hospital, Canberra, Australian Capital Territory, Australia; and ¶¶Pfizer Vaccine Research, Pearl River, New York.
Accepted for publication February 12, 2015.
Michael Nissen, MB BS is currently at GlaxosmithKline and University of Queensland, Herston, Brisbane, Queensland, Australia.
This study did not require registration on a clinical trials registry as it did not meet the WHO ICMJE definition for registration.
H.S.M., P.R., M.N., R.B. and G.R. declare their institutions received funding from Wyeth (now Pfizer) to complete the work disclosed in this manuscript. H.S.M. is a member of the Australian Technical Advisory Group on Immunisation and the Therapeutic Goods Administration Australian Influenza Vaccine Committee. H.S.M.’s institution (Women’s and Children’s Hospital) has received research grants from GlaxoSmithKline, Novartis, Sanofi Pasteur and Pfizer for independent investigator led studies and on occasion travel support for H.S.M. to present research findings. She has previously been a member of vaccine advisory boards for GlaxoSmithKline and Novartis. H.S.M. has not accepted or received any personal payment. R.B.’s institution has received funding from CSL, Hoffmann–La Roche, Sanofi, GlaxoSmithKline group of companies, Novartis, Baxter and Pfizer to conduct sponsored research, educational grants or to attend and present at scientific meetings. R.B. also received honorarium for delivering educational presentations. Any funding received is directed to a research account at The Children’s Hospital at Westmead and is not personally accepted by R.B. P.R. has received institutional funding for investigator-initiated research from GlaxoSmithKline Biologicals, Novartis, Pfizer and Merck and received travel support from Pfizer and Baxter to present study data at international meetings. M.N. previously directed the Queensland Paediatric Infectious Diseases laboratory that has performed the Meningococcal Antigen Testing System assay on Australian isolates causing invasive meningococcal disease on the behalf of Novartis. M.N. is now an employee of GlaxoSmithKline. He has received travel support from GSK and Pfizer for conference attendance and presentation of data of independent research at international meetings; honoraria from bioCSL, Novartis and Pfizer for educational lectures; institutional funding for investigator initiated research from Abbott Australasia as well as been an principal investigator on vaccine and epidemiological studies sponsored by a range of vaccine manufacturers, and in this role has received support for conference attendance, presentation of data and membership of vaccine advisory boards. M.N. is the current Chair of the Australian National Verification Committee for Measles Eradication and a past member of ATAGI. S.L. and G.R. report no other conflicts of interest. S.S., M.P., K.U.J., A.S.A. and I.S. are employed by Pfizer (Vaccine Research) and as such may own Pfizer shares. Pfizer was the funding source for the study conduct. The microbiological and serological analyses were conducted by Pfizer employees. The statistical analysis and modelling of predictors was conducted by the non-industry investigators. No funding was provided for the costs associated with the development and the publishing of the present manuscript, which was drafted and completed by the first author with contribution from all authors.
Address for correspondence: Helen S. Marshall, Vaccinology and Immunology Research Trials Unit, Women’s and Children’s Hospital, 72 King William Rd, North Adelaide, 5006 South Australia, Australia. E-mail: Helen.firstname.lastname@example.org.