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

To access publisher's full text version of this article click on the hyperlink at the bottom of the pageEpidemiology 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 Fun

Evolving epidemiology of invasive Haemophilus infections in the post-vaccination era: results from a long-term population-based study.

Historically, Haemophilus influenzae (Hi) serotype b (Hib) caused most invasive Haemophilus infections worldwide, mainly in children. In 1989 routine childhood vaccination against Hib was initiated in Iceland. We conducted a population-based study of all patients in the country with Haemophilus spp. isolated from sterile sites (n = 202), from 1983 to 2008. Epidemiology, clinical characteristics of the infections and serotypes of the isolates were compared during the pre-vaccination (1983-1989) and post-vaccination era (1990-2008). Following the vaccination, the overall incidence of Hib decreased from 6.4 to 0.3/100,000 per year (p <0.05) whereas the incidence did not change significantly for infections caused by Haemophilus sensu lato not serotype b, hereafter referred to as non-type b Hi (0.9 vs 1.2, respectively). The most frequent diagnosis prior to 1990 was meningitis caused by Hib, which was subsequently replaced by pneumonia and bacteraemia caused by non-type b Hi. Most commonly, non-type b Hi were non-typeable (NTHi; 40/59), followed by Hi serotype f (14/59) and Hi serotype a (3/59). Pregnancy was associated with a markedly increased susceptibility to invasive Haemophilus infections (RR 25.7; 95% CI 8.0-95.9, p <0.0001) compared with non-pregnant women. The case fatality rate for Hib was 2.4% but 14% for non-type b Hi, highest at the extremes of age. Hib vaccination gives young children excellent protection and decreases incidence in the elderly due to herd effect in the community. Replacement with other species or serotypes has not been noted. Pregnant women are an overlooked risk group

Molecular epidemiology of late recurrent candidaemia--a population-based study in Iceland.

To access publisher full text version of this article. Please click on the hyperlink in Additional Links field.Candidaemia is associated with high patient mortality. Among those who survive an initial episode of candidaemia, the incidence of recurrent episodes has been incompletely defined. All patients in Iceland with candidaemia in 1980-2008 were identified, and clinical information was reviewed. Episodes of candidaemia in the same patient were considered to be separate if they occurred ≥ 1 month apart or were caused by different Candida species. The isolates were genotyped by using PCR fingerprinting, and antifungal susceptibility was determined. During the 29-year period, candidaemia was diagnosed in 307 patients in Iceland, 298 of whom (97.1%) had a single episode. Overall, 206 patients survived >1 month from the first episode and were therefore at risk of recurrence, yielding 1062 patient-years of observation in the survivors. Of those, nine (4.4%) later developed recurrent candidaemia. The median time between recurrences was 6 months (range, <1 month to 14 years). Patients with late recurrences were younger (p 0.012) and more likely to have underlying gastrointestinal diseases than patients with single episodes (55.6% vs. 18.5%, respectively; p 0.017). The recurrences were caused by identical Candida sp. genotypes in two of 13 cases (15%), but by different species or dissimilar genotypes in eight of 13 (62%); isolates were missing in three cases. In conclusion, late recurrent candidaemia was a relatively rare event, and younger patients with gastrointestinal disorders were more prone to recurrent infections. The majority of late recurrences represented re-infections with new Candida strains that were susceptible to common antifungal agents.Landspitali University Hospita

Effect of vaccination on pneumococci isolated from the nasopharynx of healthy children and the middle ear of children with otitis media in Iceland

Vaccination with pneumococcal conjugate vaccines (PCVs) disrupts the pneumococcal population. Our aim was to determine the impact of the 10-valent PCV on the serotypes, genetic lineages and antimicrobial susceptibility of pneumococci isolated from children in Iceland. Pneumococci were collected between 2009-2017 from the nasopharynx of healthy children attending 15 day-care centres and from the middle ear (ME) of children with acute otitis media from the greater Reykjavik capital area. Isolates were serotyped and tested for antimicrobial susceptibility. Whole genome sequencing (WGS) was performed on alternate isolates from 2009-2014 and serotypes and multilocus sequence types (STs) were extracted from the WGS data. Two study periods were defined: 2009-2011 (PreVac) and 2012-2017 (PostVac). The overall nasopharyngeal carriage rate was similar between the two periods (67.3% PreVac and 61.5% PostVac, p=0.090). Vaccine-type (VT) pneumococci decreased and nonvaccine-type (NVT) pneumococci (serotypes 6C, 15A, 15B/C, 21, 22F, 23A, 23B, 35F, 35B) significantly increased post-PCV introduction in different age strata. The total number of pneumococci recovered from ME samples significantly decreased, as did the proportion that were VTs, although NVT pneumococci (6C, 15B/C, 23A and 23B) increased significantly. Most serotype 6C pneumococci were multidrug-resistant (MDR). Serotype 19F was the predominant serotype associated with ME and it significantly decreased post-PCV introduction: these isolates were predominantly MDR and of the Taiwan19F-14 PMEN lineage. Overall, the nasopharyngeal carriage rate remained constant and the number of ME-associated pneumococci decreased significantly post-PCV introduction; however, there was a concomitant and statistically significant shift from VTs to NVTs in both collections of pneumococci

Changing epidemiology of group B streptococcal infections among adults in Iceland: 1975–2014

To access publisher's full text version of this article click on the hyperlink at the bottom of the pageWe 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).governments of Iceland, Lichtenstein and Norway Fundacao para a Ciencia e a Tecnologia SFRH/BPD/80038/2011 Landspitali University Hospital Research Fun

Vaccination of Icelandic children with the 10-valent pneumococcal vaccine leads to a significant herd effect among adults in Iceland

The introduction of pneumococcal conjugate vaccines (PCV) into childhood vaccination programs has reduced carriage of vaccine serotypes and pneumococcal disease. The 10-valent PCV was introduced in Iceland in 2011. The aim of this study was to determine PCV impact on the prevalence of serotypes, genetic lineages and antimicrobial-resistant pneumococci isolated from the lower respiratory tract (LRT) of adults.Pneumococci isolated during 2009-2017 at the Landspitali University Hospital, were included (n=797). The hospital serves almost three-quarters of the Icelandic population. Isolates were serotyped and tested for antimicrobial susceptibility, and the genome of every other isolate from 2009-2014 was sequenced (n=275). Serotypes and multilocus sequence types (STs) were extracted from the genome data. Three study periods were defined: 2009-2011 (PreVac), 2012-2014 (PostVac-I) and 2015-2017 (PostVac-II).The total number of isolates and vaccine-type (VT) pneumococci decreased from PreVac to PostVac-II (n=314 vs n=230; p=0.002 and n=170 vs n=33; p<0.001, respectively), but nonvaccine-type (NVT) pneumococci increased among adults 18-64 years old (n=56 vs n=114; p=0.008). Serotype 19F decreased in the PostVac-II period: these isolates were all multidrug-resistant (MDR) and were members of the Taiwan19F-14 PMEN lineage. Serotype 6A decreased among adults ≥65 years old PostVac-II (p=0.037), while serotype 6C increased (p=0.021) and most serotype 6C isolates were MDR. Non-encapsulated S. pneumoniae (NESp) increased among adults 18-64 years old PostVac-II and the majority were MDR (p=0.028).An overall reduction in the number of LRT samples, pneumococcal-positive cultures, and significant changes in the serotype distribution became evident within four years thereby demonstrating a significant herd effect

Correction for van Tonder et al., Genomics Reveals the Worldwide Distribution of Multidrug-Resistant Serotype 6E Pneumococci.

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