Journal Article

Trends in serotypes and sequence types among cases of invasive pneumococcal disease in Scotland, 1999–2010

Diggle, Mathew, Inverarity, Donald, McDonald, Eisin, Smith, Andrew, Denham, Barbara, Edwards, Giles F.S., McMenamin, Jim, Flasche, Stefan, Greenhalgh, David, Jefferies, Johanna M., Robertson, Chris, Lamb, Karen E., Clarke, Stuart C., Mitchell, Tim J.

2014

Overview

•PCV7 was introduced for routine use in Scotland in 2006.•Analysis of serotype and sequence type distributions in IPD pre and post PCV7 use.•Serotype changes may be driven by pre-PCV7 serotype and sequence type associations.•Implications for possible effects of introducing higher valency vaccines.•Could aid in predicting replacement serotypes in disease. The 7-valent pneumococcal conjugate vaccine (Prevenar®, Wyeth; PCV7) was introduced to the UK paediatric immunisation schedule in 2006. This study investigates trends in serotypes and multi locus sequence types (STs) among cases of invasive pneumococcal disease (IPD) in Scotland prior to, and following, the introduction of PCV7. Scottish Invasive Pneumococcal Disease Enhanced Surveillance has records of all cases of IPD in Scotland since 1999. Cases diagnosed from blood or cerebrospinal fluid isolates until 2010 were analysed. Logistic and poisson regression modelling was used to assess trends prior to and following the introduction of PCV7. Prior to PCV7 use, on average 650 cases of IPD were reported each year; 12% occurred in those aged <5 years and 35% affected those aged over 65 years. Serotypes in PCV7 represented 47% of cases (68% in <5 year olds). The serotype and ST distribution was relatively stable with only serotype 1 and associated ST 306 showing an increasing trend. PCV7 introduction was associated with a 69% (95% CI: 50%, 80%) reduction in the incidence of IPD among those aged <5 years, a 57% (95% CI: 47%, 66%) reduction among those aged 5–64 years but no significant change among those aged 65 years and over where increases in non-PCV7 serotypes were observed. Serotypes which became more prevalent post-PCV7 are those which were associated with STs related to the PCV7 serotypes. Routine serotyping and sequence typing in Scotland allowed the assessment of the relationship between the capsule and the clones in the post vaccination era. Changes in the distribution of serotypes post PCV7 introduction appear to be driven by associations between serotypes and STs prior to PCV7 introduction. This has implications for the possible effects of the introduction of higher valency vaccines and could aid in predicting replacement serotypes in IPD.

• Publisher: Elsevier Ltd,Elsevier,Elsevier Limited
• Subject: Adolescent / Adult / Aged / Allergy and Immunology / Applied microbiology / Bacterial diseases / Biological and medical sciences / blood / cerebrospinal fluid / Child / Child, Preschool / clones / Fundamental and applied biological sciences. Psychology / Heptavalent Pneumococcal Conjugate Vaccine / Human bacterial diseases / Humans / Immunization / Incidence / Infant / Infant, Newborn / Infectious diseases / Invasive pneumococcal disease / Life Sciences / loci / Logistic Models / Medical sciences / Microbiology / Middle Aged / monitoring / PCV7 / Pneumococcal Infections - epidemiology / Pneumococcal Infections - prevention & control / Pneumococcal Vaccines - administration & dosage / Pneumonia / Population Surveillance / prediction / Santé publique et épidémiologie / Scotland / Scotland - epidemiology / Sequence type / Serogroup / Serotype / serotypes / Serotyping / Staphylococcal infections, streptococcal infections, pneumococcal infections / Streptococcus pneumoniae / Streptococcus pneumoniae - classification / Trends / vaccination / Vaccines / Vaccines, antisera, therapeutical immunoglobulins and monoclonal antibodies (general aspects) / Vaccines, Conjugate - administration & dosage / Young Adult