Invasive infections due to Streptococcus pyogenes: seasonal variation of severity and clinical characteristics, Iceland, 1975 to 2012.

• Main Authors: Olafsdottir, L B, Erlendsdóttir, H, Melo-Cristino, J, Weinberger, D M, Ramirez, M, Kristinsson, K G, Gottfredsson, M
• Other Authors: Landspitali Univ Hosp, Dept Med, Reykjavik, Iceland, Landspitali Univ Hosp, Reykjavik, Iceland, Univ Iceland, Fac Med, Sch Hlth Sci, Reykjavik, Iceland, Univ Lisbon, Fac Med, Inst Mol Med, Inst Microbiol, P-1699 Lisbon, Portugal, NIH, Div Int Epidemiol & Populat Studies, Fogarty Int Ctr, Bethesda, MD 20892 USA, Yale Univ, Dept Epidemiol Microbial Dis, Sch Publ Hlth, New Haven, CT USA
• Format: Article in Journal/Newspaper
• Language: English
• Published: Eur Centre Dis Prevention & Control 2014
• Subjects: Bakteríusjúkdómar; Gerlar; Tíðni; Adolescent; Adult; Age Distribution; Aged; 80 and over; Bacterial Proteins; Carrier Proteins; Child; Preschool; Humans; Iceland; Incidence; Middle Aged; Population Surveillance; Retrospective Studies; Seasons; Severity of Illness Index; Sex Distribution; Streptococcal Infections; Streptococcus pyogenes; Virulence; Young Adult
• Online Access: http://hdl.handle.net/2336/325546

To access publisher's full text version of this article click on the hyperlink at the bottom of the page Epidemiology and clinical characteristics of invasive Group A streptococcal infections (IGASI) are highly variable. Long-term studies are needed to understand the interplay between epidemiology and virulence. In a population-based study of IGASI in Iceland from 1975 to 2012, 288 cases were identified by positive cultures from normally sterile body sites. Charts were reviewed retrospectively and emm-types of viable Streptococcus pyogenes isolates (n=226) determined. Comparing the first and last decade of the study period, IGASI incidence increased from 1.09 to 3.96 cases per 100,000 inhabitants per year. The most common were emm types 1 (25%), 28 (11%) and 89 (11%); emm1 strains were most likely to cause severe infections. Infections in adults were significantly more likely to be severe during the seasonal peak from January to April (risk ratio: 2.36, 95% confidence interval: 1.34–4.15). Significant seasonal variability in severity was noted among patients with diagnosis of sepsis, respiratory infection and cellulitis, with 38% of severe infections in January to April compared with 16% in other months (p<0.01). A seasonal increase in severity of IGASI suggested that generalised seasonal increase in host susceptibility, rather than introduction of more virulent strains may play a role in the pathogenesis of these potentially fatal infections. Icelandic Center for Research, Rannis/100436021 Landspitali University Hospital Science Fund