title: Changing epidemiology of group B streptococcal infections among adults in Iceland: 1975-2014.
abstract: We studied the bacterial characteristics and incidence of invasive infections caused by group B streptococci (GBS) in adults in Iceland in 1975-2014. A total of 145 isolates were characterized by serotyping, antimicrobial susceptibility, multilocus sequence typing and surface protein gene profiling. Disease incidence increased during the studied period (p <0.001), reaching 2.17 cases/100 000 person-years in 2013-14. Overall, serotype Ia was the most frequently found (23%), but serotypes Ib, II, III and V showed similar prevalence (14%-17%). Although there were notable changes in the proportion of most serotypes during the study period, only the decline of serotype III was statistically supported (p = 0.003) and was reflected in a decrease of clonal complexes CC17 and CC19 that included most serotype III isolates (p <0.04). On the other hand, the increase in frequency of CC1 was caused by two lineages expressing distinct serotypes: ST1/V/alp3 and ST196/IV/eps. Underlying the relative stability of serotype Ia were major changes in the lineages expressing this serotype, with an increase in the relative importance of CC23, including both ST23/Ia/eps and ST24/Ia/bca lineages, and a decrease in CC7. Nine cases of invasive GBS disease were caused by ST7, of possible zoonotic origin. All isolates were susceptible to penicillin. Rates of erythromycin and clindamycin resistance were 8.3% and 9.7%, respectively. An over-representation of resistance solely to clindamycin was associated with the unusual lsaC gene and serotype III ST19/rib lineage (p <0.001).
authors.affiliation: Department of Clinical Microbiology, Landspítali University Hospital, Reykjavik, Iceland; University of Iceland, Faculty of Medicine, Reykjavik, Iceland.
authors.forename: E S
authors.initials: ES
authors.lastname: Björnsdóttir
authors.affiliation: Instituto de Microbiologia, Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.
authors.forename: E R
authors.initials: ER
authors.lastname: Martins
authors.affiliation: Department of Clinical Microbiology, Landspítali University Hospital, Reykjavik, Iceland; University of Iceland, Faculty of Medicine, Reykjavik, Iceland.
authors.forename: H
authors.initials: H
authors.lastname: Erlendsdóttir
authors.affiliation: Department of Clinical Microbiology, Landspítali University Hospital, Reykjavik, Iceland; University of Iceland, Faculty of Medicine, Reykjavik, Iceland.
authors.forename: G
authors.initials: G
authors.lastname: Haraldsson
authors.affiliation: Instituto de Microbiologia, Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.
authors.forename: J
authors.initials: J
authors.lastname: Melo-Cristino
authors.affiliation: Department of Clinical Microbiology, Landspítali University Hospital, Reykjavik, Iceland; University of Iceland, Faculty of Medicine, Reykjavik, Iceland.
authors.forename: K G
authors.initials: KG
authors.lastname: Kristinsson
authors.affiliation: Instituto de Microbiologia, Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal. Electronic address: ramirez@fm.ul.pt.
authors.forename: M
authors.initials: M
authors.lastname: Ramirez
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D024881:Drug Resistance, Bacterial; D005260:Female; D005838:Genotype; D006801:Humans; D007055:Iceland / Q000453:epidemiology; D015994:Incidence; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D012703:Serotyping; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013292:Streptococcus agalactiae / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D055815:Young Adult
chemical_list: D008565:Membrane Proteins
keywords: Adults; Streptococcus agalactiae; antimicrobial resistance; bacterial capsules; epidemiology; invasive infection; molecular epidemiology; multilocus sequence typing