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Background: Streptococcus pneumoniae serotype 8 incidence has increased in Denmark after the introduction of pneumococcal conjugated vaccines (PCV). The mechanism behind the serotype 8 replacement is not well understood. In this study, we aimed to present epidemiological data on invasive pneumococcal disease (IPD) and molecular characterization of 96 serotype 8 clinical isolates., Methods: IPD data from 1999 to 2019 were used to calculate the incidence and age distribution. Whole-genome sequencing (WGS) analysis was performed on 96 isolates (6.8% of the total serotype 8 IPD isolates in the period) to characterize the isolates with respect to pneumococcal lineage traits, a range of genes with potential species discrimination, presence of colonization and virulence factors, and molecular resistance pattern., Results: The serotype 8 IPD incidence increased significantly (P < 0.05) for the age groups above 15 years after the introduction of PCV13, primarily affecting the elderly (65+). All isolates were phenotypically susceptible to penicillin, erythromycin and clindamycin. Molecular characterization revealed seven different MLST profiles with ST53 as the most prevalent lineage (87.5%) among the analyzed serotype 8 isolates. The genes covering the cell-surface proteins: lytA, rspB, pspA, psaA & Xisco and the pneumococcal toxin pneumolysin = ply were present in all isolates, while genes for the membrane transporter proteins: piaA/piaB/piaC; the capsular genes: cpsA (wzg) & psrP; the metallo-binding proteins zmpB & zmpC; and the neuroamidase proteins: nanA/nanB were variably present. Surprisingly, the putative transcriptional regulator gene SP2020 was not present in all isolates (98%). Susceptibility to penicillin, erythromycin and clindamycin was molecularly confirmed., Conclusion: The observed serotype 8 replacement was not significantly reflected with a change in the MLST profile or changes in antibiotic resistance- or virulence determinants.

Objective: To describe trends in incidence rates of adenoidectomy in children in Denmark from 1998-2014 and to look for possible explanatory factors such as intranasal steroids and pneumococcal vaccination., Design: A nationwide, population-based, retrospective, interrupted time-series analysis, using data from Danish registries., Setting: Hospitals and private Ear, Nose and Throat clinics., Participants: Children who underwent adenoidectomy from 1998 to 2014 in Denmark., Main Outcome Measure: Adenoidectomy., Methods: The National Patient Register and the National Health insurance Service Register were used to identify all adenoidectomies performed in children. The National Prescription Register supplied data on intranasal steroids., Results: A total of 174,557 adenoidectomies were identified, distributed among 153 022 children. The annual incidence rate was stable at around 11 per 1000 person-years from 1998 to 2004. A decrease was seen from 2004 reaching 7.9 in 2009, followed by an increase to 9.1 in 2014. The highest age-specific incidence rates were seen at 2-3 years of age. An estimated 14% of children born in 2014 will have had adenoidectomy performed before turning 16 years old. The proportion of adenoidectomies performed in private clinics compared with hospitals was 90%., Conclusion: From 1998 to 2004 the incidence rate of adenoidectomy in children in Denmark was among the highest in the world with around 11 per 1000 person-years. A decrease to 7.9 was seen from 2004 to 2009. We found no inverse correlation on a national level between the incidence rates of adenoidectomy and intranasal steroid, nor the introduction of the pneumococcal vaccine. The amount of intranasal steroids used in children in Denmark was negligible compared with adenoidectomy., (© 2019 John Wiley & Sons Ltd.)