title: High nasopharyngeal carriage of non-vaccine serotypes in Western Australian aboriginal people following 10 years of pneumococcal conjugate vaccination.
abstract: BACKGROUND
  Invasive pneumococcal disease (IPD) continues to occur at high rates among Australian Aboriginal people. The seven-valent pneumococcal conjugate vaccine (7vPCV) was given in a 2-4-6-month schedule from 2001, with a 23-valent pneumococcal polysaccharide vaccine (23vPPV) booster at 18 months, and replaced with 13vPCV in July 2011. Since carriage surveillance can supplement IPD surveillance, we have monitored pneumococcal carriage in western Australia (WA) since 2008 to assess the impact of the 10-year 7vPCV program.
  
  
  METHODS
  We collected 1,500 nasopharyngeal specimens from Aboriginal people living in varied regions of WA from August 2008 until June 2011. Specimens were cultured on selective media. Pneumococcal isolates were serotyped by the quellung reaction.
  
  
  RESULTS
  Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis were carried by 71.9%, 63.2% and 63.3% respectively of children <5 years of age, and 34.6%, 22.4% and 27.2% of people ≥5 years. Of 43 pneumococcal serotypes identified, the most common were 19A, 16F and 6C in children <5 years, and 15B, 34 and 22F in older people. 7vPCV serotypes accounted for 14.5% of all serotypeable isolates, 13vPCV for 32.4% and 23vPPV for 49.9%, with little variation across all age groups. Serotypes 1 and 12F were rarely identified, despite causing recent IPD outbreaks in WA. Complete penicillin resistance (MIC ≥2µg/ml) was found in 1.6% of serotype 19A (5.2%), 19F (4.9%) and 16F (3.2%) isolates and reduced penicillin susceptibility (MIC ≥0.125µg/ml) in 24.9% of isolates, particularly 19F (92.7%), 19A (41.3%), 16F (29.0%). Multi-resistance to cotrimoxazole, tetracycline and erythromycin was found in 83.0% of 23F isolates. Among non-serotypeable isolates 76.0% had reduced susceptibility and 4.0% showed complete resistance to penicillin.
  
  
  CONCLUSIONS
  Ten years after introduction of 7vPCV for Aboriginal Australian children, 7vPCV serotypes account for a small proportion of carried pneumococci. A large proportion of circulating serotypes are not covered by any currently licensed vaccine.
authors.affiliation: Telethon Institute for Child Health Research, Centre for Child Health Research, the University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Deirdre A
authors.initials: DA
authors.lastname: Collins
authors.affiliation: Telethon Institute for Child Health Research, Centre for Child Health Research, the University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Anke
authors.initials: A
authors.lastname: Hoskins
authors.affiliation: Division of Microbiology & Infectious Diseases, PathWest Laboratory Medicine WA, Perth, Western Australia, Australia.
authors.forename: Jacinta
authors.initials: J
authors.lastname: Bowman
authors.affiliation: Division of Microbiology & Infectious Diseases, PathWest Laboratory Medicine WA, Perth, Western Australia, Australia.
authors.forename: Jade
authors.initials: J
authors.lastname: Jones
authors.affiliation: Division of Microbiology & Infectious Diseases, PathWest Laboratory Medicine WA, Perth, Western Australia, Australia ; Microbiology & Immunology, School of Pathology and Laboratory Medicine, the University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Natalie A
authors.initials: NA
authors.lastname: Stemberger
authors.affiliation: School of Paediatrics and Child Health, University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Richmond
authors.affiliation: Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia.
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Leach
authors.affiliation: Telethon Institute for Child Health Research, Centre for Child Health Research, the University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Deborah
authors.initials: D
authors.lastname: Lehmann
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000890:Anti-Infective Agents / Q000494:pharmacology; D002353:Carrier State / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology* / Q000517:prevention & control; D002648:Child; D002675:Child, Preschool; D005260:Female; D005843:Geography; D006801:Humans; D007223:Infant; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009305:Nasopharynx / Q000276:immunology / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000276:immunology* / Q000382:microbiology* / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000276:immunology*; D044382:Population Groups; D015995:Prevalence; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification; D014611:Vaccination; D018074:Vaccines, Conjugate / Q000276:immunology*; D014904:Western Australia / Q000453:epidemiology
chemical_list: D000890:Anti-Infective Agents; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate