Invasive Pneumococcal Disease in Persons With Predisposing Factors is Dominated by Non-vaccine Serotypes in Southwest Sweden

Abstract

Background: The pneumococcal conjugate vaccine PCV7 was introduced in Southwest Sweden in the child vaccination program in 2009, followed by PCV13 in 2010 and PCV10 in 2015. In this study we assessed the pneumococcal serotype distribution in relation to predisposing factors, clinical manifestations and outcome during seven years after PCV introduction. Methods: Clinical data from 1,278 patients with 1,304 episodes of IPD between January 2009 and December 2015 in Region Västra Götaland, Sweden, were retrospectively collected from medical records. Pneumococcal isolates were serotyped by gel diffusion and/or Quellung reactions performed at the Public Health Agency in Sweden. Results: With the exception of serotype 3, the prevalence of PCV13 serotypes decreased during the study period, from 76% of all IPD episodes in 2009 to 25% in 2015 (p<0.001) while non-PCV13 serotypes increased, mainly among patients ≥ 65 years and in patients with predisposing factors (p<0.001 for both). Patients with predisposing factors were more likely to have IPD caused by a serotype not included in PCV13 rather than a vaccine-included serotype. Serotype 3 was associated with intensive care unit admissions while serotype 1 and 7F caused IPD among healthier and younger patients. PCV13 serotypes were associated with invasive pneumonia, and non-PCV13 serotypes were associated with bacteremia with unknown focus and with manifestations other than pneumonia or meningitis. Conclusions: Non-PCV13 serotypes caused the majority of IPD cases in Southwest Sweden, especially in patients ≥65 years and in patients with predisposing factors. Serotype 3, included in PCV13, was prevalent and often caused severe disease.

Parapneumonic effusions related toStreptococcus pneumoniae: serotype and disease severity trends from 2006 to 2018 in Bristol, UK

“…Serotype 1 expresses a zwitterionic and structurally diverse polysaccharide capsule, which uniquely may act as a T-cell dependent antigen (31). This serotype rarely causes asymptomatic nasopharyngeal colonization but is a commonly isolated in IPD (28), and frequently causes invasive pneumonia (32). Studies suggests serotype 1 is more likely to be identified in young patients, and in some studies it is the most frequent cause of pneumococcal pleural infection, with increasing pleural infection incidence attributable to this serotype (11,13).…”