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Background: Penicillin non-susceptible (PNSP) and multi-resistant pneumococci have been prevalent in Iceland since early nineties, mainly causing problems in treatment of acute otitis media. The 10-valent protein conjugated pneumococcal vaccine (PHiD-CV) was introduced into the childhood vaccination program in 2011. The aim of the study was to investigate the changes in antimicrobial susceptibility and serotype distribution of penicillin non-susceptible pneumococci (PNSP) in Iceland 2011-2017., Methods and Findings: All pneumococcal isolates identified at the Landspítali University Hospital in 2011-2017, excluding isolates from the nasopharynx and throat were studied. Susceptibility testing was done according to the EUCAST guidelines using disk diffusion with chloramphenicol, erythromycin, clindamycin, tetracycline, trimethoprim/sulfamethoxazole and oxacillin for PNSP screening. Penicillin and ceftriaxone minimum inhibitory concentrations (MIC) were measured for oxacillin resistant isolates using the E-test. Serotyping was done using latex agglutination and/or multiplex PCR. The total number of pneumococcal isolates that met the study criteria was 1,706, of which 516 (30.2%) were PNSP, and declining with time. PNSP isolates of PHiD-CV vaccine serotypes (VT) were 362/516 (70.2%) declining with time, 132/143 (92.3%) in 2011 and 17/54 (31.5%) in 2017. PNSP were most commonly of serotype 19F, 317/516 isolates declining with time, 124/143 in 2011 and 15/54 in 2017. Their number decreased in all age groups, but mainly in the youngest children. PNSP isolates of non PHiD-CV vaccine serotypes (NVT) were 154/516, increasing with time, 11/14, in 2011 and 37/54 in 2017. The most common emerging NVTs in 2011 and 2017 were 6C, 1/143 and 10/54 respectively., Conclusions: PNSP of VTs have virtually disappeared from children with pneumococcal diseases after the initiation of pneumococcal vaccination in Iceland and a clear herd effect was observed. This was mainly driven by a decrease of PNSP isolates belonging to a serotype 19F multi-resistant lineage. However, emerging multi-resistant NVT isolates are of concern., Competing Interests: This work is an investigator-initiated study that was supported by grants from: - The Landspítali University Hospital Research Fund (MÁH) https://www.landspitali.is - GlaxoSmithKline Biologicals SA https://www.gsk.com The authors declare that this does not alter our adherence to PLOS ONE policies on sharing data and materials. Neither GlaxoSmithKline Biologicals SA, nor Landspítali University Hospital Research Fund had any role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Vaccinations with the 10-valent pneumococcal conjugated vaccine (PHiD-CV) started in Iceland in 2011. Protein D (PD) from H. influenzae , which is coded for by the hpd gene, is used as a conjugate in the vaccine and may provide protection against PD-positive H. influenzae We aimed to evaluate the effect of PHiD-CV vaccination on H. influenzae in children, both in carriage and in acute otitis media (AOM). H. influenzae was isolated from nasopharyngeal swabs collected from healthy children attending 15 day care centers in 2009 and from 2012 to 2017 and from middle ear (ME) samples from children with AOM collected from 2012 to 2017. All isolates were identified using PCR for the hpd and fucK genes. Of the 3,600 samples collected from healthy children, 2,465 were culture positive for H. influenzae (68.5% carriage rate); of these, 151 (6.1%) contained hpd -negative isolates. Of the 2,847 ME samples collected, 889 (31.2%) were culture positive for H. influenzae ; of these, 71 (8.0%) were hpd negative. Despite the same practice throughout the study, the annual number of ME samples reduced from 660 in 2012 to 330 in 2017. The proportions of hpd -negative isolates in unvaccinated versus vaccinated children were 5.6% and 7.0%, respectively, in healthy carriers, and 5.4% and 7.8%, respectively, in ME samples. The proportion of hpd -negative isolates increased with time in ME samples but not in healthy carriers. The number of ME samples from children with AOM decreased. The PHiD-CV had no effect on the proportion of the hpd gene in H. influenzae from carriage, but there was an increase in hpd -negative H. influenzae in otitis media. The proportions of hpd -negative isolates remained similar in vaccinated and unvaccinated children., (Copyright © 2019 Sveinsdóttir et al.)

The introduction of pneumococcal conjugate vaccines (PCVs) 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 between 2009 and 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 collected between 2009 and 2014 was sequenced ( n  = 275). Serotypes and multilocus sequence types (STs) were extracted from the genome data. Three study periods were defined, 2009 to 2011 (PreVac), 2012 to 2014 (PostVac-I), and 2015 to 2017 (PostVac-II). The total number of isolates and vaccine-type (VT) pneumococci decreased from PreVac to PostVac-II ( n  = 314 versus n  = 230 [ p  = 0.002] and n  = 170 versus n  = 33 [ p  < 0.001], respectively), but non-vaccine-type (NVT) pneumococci increased among adults 18 to 64 years old ( n  = 56 versus 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 Taiwan 19F -14 PMEN lineage. Serotype 6A decreased among adults ≥65 years old in the PostVac-II period ( p  = 0.037), while serotype 6C increased ( p  = 0.021) and most serotype 6C isolates were MDR. Nonencapsulated Streptococcus pneumoniae (NESp) isolates increased among adults 18 to 64 years old in the PostVac-II period, and the majority were MDR ( p  = 0.028). An overall reduction in the number of LRT samples and pneumococcus-positive cultures and significant changes in the serotype distribution became evident within 4 years, thereby demonstrating a significant herd effect., (Copyright © 2019 Quirk et al.)

Background: Information on pneumococcal serotype distribution before vaccination is a prerequisite for evaluation of vaccine effect. The aim was to investigate the prevalence of pneumococcal serotypes isolated from middle ear (ME), lower respiratory tract (LRT) and from invasive disease (IPD) in Iceland prior to implementation of ten-valent pneumococcal Haemophilus influenzae protein D conjugate vaccine (PHiD-CV-10) into the infant vaccination program (April 2011)., Methods and Findings: All isolates cultured 2007-2011 from ME, LRT and IPD identified as pneumococci were serotyped and tested for susceptibility at the Clinical Microbiology Department, Landspitali University Hospital that serves approximately 85% of the Icelandic population. Pneumococcal isolates were 1711 and 1616 (94.4%) were available for serotyping and included. Isolates belonging to PHiD-CV10 serotypes (VTs) were 1052 (65.1%). Isolates from ME were 879 (54.4%), with 639 (72.7%) from 0-1 year old patients and 651 of VTs (74%). Isolates from LRT were 564 (34.9%), with 292 (51.8%) from ≥65 years old patients, and 300 (53.2%) of VTs. IPD isolates were 173 (10.7%), although more evenly distributed according to age than isolates from the other sites most were from adults and the youngest age group,101 (58.4%) isolates were of VTs. The most common serotype was 19F, 583 (36.1%). Its prevalence was highest in ME, 400 (45.5%), 172 (30.5%) in LRT and 11 isolates (6.4%), in IPD. Penicillin non-susceptible isolates were 651 (40.3%), mainly belonging to VTs, 611 (93.9%), including 535 (82.2%) of 19F., Conclusions: Multiresistant isolates of serotype 19F were highly prevalent, especially from ME of young children but also from LRT of adults. Serotype 14 was the most common serotype in IPD. The rate of VTs was high and almost all PNSP were of VTs. There was great difference in vaccine coverage between sampling sites, also reflecting difference in vaccine coverage by age groups., Competing Interests: Competing Interests: Some of the authors (HE, ÁH and KGK) have received a research grant from GSK, to study the effectiveness of pneumococcal vaccination in Iceland. That study is an investigator initiated study with no conflicting interests related to the current study. GSK did not fund this specific study. There are no patents, products in development or marketed products to declare. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

The pneumococcus is a leading global pathogen and a key virulence factor possessed by the majority of pneumococci is an antigenic polysaccharide capsule ('serotype'), which is encoded by the capsular ( cps ) locus. Approximately 100 different serotypes are known, but the extent of sequence diversity within the cps loci of individual serotypes is not well understood. Investigating serotype-specific sequence variation is crucial to the design of sequence-based serotyping methodology, understanding pneumococcal conjugate vaccine (PCV) effectiveness and the design of future PCVs. The availability of large genome datasets makes it possible to assess population-level variation among pneumococcal serotypes and in this study 5405 pneumococcal genomes were used to investigate cps locus diversity among 49 different serotypes. Pneumococci had been recovered between 1916 and 2014 from people of all ages living in 51 countries. Serotypes were deduced bioinformatically, cps locus sequences were extracted and variation was assessed within the cps locus, in the context of pneumococcal genetic lineages. Overall, cps locus sequence diversity varied markedly: low to moderate diversity was revealed among serogroups/types 1, 3, 7, 9, 11 and 22; whereas serogroups/types 6, 19, 23, 14, 15, 18, 33 and 35 displayed high diversity. Putative novel and/or hybrid cps loci were identified among all serogroups/types apart from 1, 3 and 9. This study demonstrated that cps locus sequence diversity varied widely between serogroups/types. Investigation of the biochemical structure of the polysaccharide capsule of major variants, particularly PCV-related serotypes and those that appear to be novel or hybrids, is warranted.

Objectives The objective of this study was to investigate the prevalence of pilus islets [pilus islet 1 (PI-1) and pilus islet 2 (PI-2)] in pneumococcal isolates from healthy Icelandic preschool children attending day care centres, prior to the introduction of conjugated pneumococcal vaccine, and the association of the pilus islets with vaccine serotypes and antibiotic resistance. Methods Nasopharyngeal swabs were collected from 516 healthy children attending day care centres in Reykjavik in March and April 2009. Infant vaccination was started in 2011, thus the great majority of the children were unvaccinated. Pneumococci were cultured selectively, tested for antimicrobial susceptibility and serotyped. The presence of PI-1 and PI-2 was detected using PCR. Results A total of 398 viable isolates were obtained of which 134 (33.7%) showed the presence of PI-1. PI-1-positive isolates were most often seen in serotype 19F [30/31 (96.8%)] and were of clade I, and in 6B [48/58 (82.8%)] of clade II. PI-2-positive isolates were most common in serotype 19F [27/31 (87.1%)]; all of them were also PI-1 positive. Of the PI-1-positive and PI-2-positive isolates, 118 (88.1%) and 31 (81.6%), respectively, were of vaccine serotypes. Both PI-1 and PI-2 were more often present in penicillin-non-susceptible pneumococci (PNSP) than in penicillin-susceptible pneumococci [PI-1 in 41/58 (70.7%) and 93/340 (27.4%), respectively, and PI-2 in 28/58 (48.3%) and 10/340 (2.9%), respectively]. Conclusions Genes for PI-1 and/or PI-2 in pneumococci isolated from healthy Icelandic children are mainly found in isolates of vaccine serotypes and in PNSP isolates belonging to multiresistant international clones that have been endemic in the country. ` [ABSTRACT FROM AUTHOR]