Reduction of antimicrobial resistant pneumococci seven years after introduction of pneumococcal vaccine in Iceland.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked DownloadBackground: 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.Landspitali University Hospital Research Fun

Pneumococcal vaccination: Direct and herd effect on carriage of vaccine types and antibiotic resistance in Icelandic children

Background Since the introduction of pneumococcal conjugate vaccines, vaccine type pneumococcal carriage and disease has decreased world-wide. The aim was to monitor changes in the nasopharyngeal carriage of pneumococci, the distribution of serotypes and antimicrobial resistance in children before and after initiation of the 10-valent pneumococcal vaccination in 2011, in a previously unvaccinated population. Methods Repeated cross-sectional study at 15 day-care centres in greater Reykjavik area. Nasopharyngeal swabs were collected yearly in March from 2009 to 2015. The swabs were selectively cultured for pneumococci, which were serotyped using latex agglutination and/or PCR and antimicrobial susceptibility determined. Two independent studies were conducted. In study 1, on total impact, isolates from children aged <4 years were included. The vaccine-eligible-cohort (birth-years: 2011–2013, sampled in 2013–2015) was compared with children at the same age born in 2005–2010 and sampled in 2009–2012. In study 2 on herd effect, isolates from older non-vaccine-eligible children (3.5–6.3 years) were compared for the periods before and after the vaccination (2009–2011 vs 2013–2015. Vaccine impact was determined using 1-odds-ratio. Results Following vaccination, the vaccine impact on vaccine type acquisition was 94% (95% CI: 91–96%) in study 1 and 56% (95% CI: 44–65%) in study 2. The impact on serotype 6 A was 33% (95% CI: −9%; 59%) in study 1 and 42% (95% CI: 10–63%) in study 2 with minimal effect on 19A. The non-vaccine serotypes/groups 6C, 11, 15 and 23B were the most common serotypes/groups after vaccination. Isolates from the vaccine-eligible-cohort had lower penicillin MICs, less resistance to erythromycin and co-trimoxazole and less multi resistance than isolates from the control-group. Conclusions The efficacy of the vaccination on vaccine serotypes was high, and a milder effect on vaccine-associated-serotype 6A was observed for the vaccine-eligible-cohort. There was a significant herd effect on vaccine types in older non-vaccine-eligible children. Overall antimicrobial non-susceptibility was reduced.Funding for this study was provided by GlaxoSmithKline Biologicals SA and a grant was received from the Landspitali University Hospital Research Fund. GlaxoSmithKline Biologicals SA was provided the opportunity to review a draft version of this manuscript but the authors are solely responsible for final content and interpretation. The authors received no financial support or other form of compensation related to the development of the manuscript.Peer Reviewe

Serotype and molecular epidemiology of pneumococci before and after pneumococcal vaccination

The pneumococcus is a major human pathogen that causes morbidity and mortality worldwide. Pneumococci are normally carried asymptomatically in the nasopharynx of healthy pre-school children. Pneumococcal infections can range from acute otitis media (AOM) and pneumonia to invasive pneumococcal disease (IPD). Vaccination with conjugate pneumococcal vaccines (PCVs) leads to a reduction of serotypes targeted by the vaccines (vaccine-type, VT) but can also lead to replacement by serotypes not targeted by PCVs (nonvaccine-type, NVT). Iceland introduced the 10-valent PCV (PHiD-CV, GSK) into the national immunization program in 2011. The aim of the study was to assess the impact of PHiD-CV on pneumococci isolated from samples from the nasopharynx of healthy children attending day-care centres (DCCs), middle ear (ME) from children with AOM and lower respiratory tract (LRT) from adults with suspected pneumonia. Serotype distribution, genetic lineages and antimicrobial resistance was analysed by comparing the period before vaccine introduction (PreVac; 2009-2011) to the period post vaccine introduction (PostVac; 2012-2017). Nasopharyngeal swabs were collected annually (March, 2009-2017), from children <7 years old attending 15 DCCs in the greater Reykjavik area. All pneumococci isolated from ME samples from children <7 years old submitted to Landspitali University Hospital from 2009-2017 were included. ME isolates were analysed as the mean number of isolates detected each year (avg/yr) to correct for the difference in the number of years between the two study periods. All pneumococci from LRT samples from adults ≥18 years old were included in the study. The LRT isolates were analysed as the number of detected isolates according to the population size for the referral area. Two PostVac periods were defined for LRT: PostVac-I; 2012-2014 and PostVac-II; 2015-2017. All isolates were serotyped using latex agglutination and/or PCR and/or sequence based serotyping. Antimicrobial susceptibility testing was according to the methods and criteria of EUCAST. Whole genome sequencing (WGS) was done on selected isolates. Multilocus sequence types (STs) were extracted from the WGS data and STs were assigned to clonal complexes (CCs). Phylogenetic trees were constructed and annotated with serotypes and CCs. A two-sided Fisher´s exact test was used to calculate p-values and the level of significance was set ≤0.05. A total of 5,570 pneumococcal isolates were analysed: 3,020 from carriage, 1,330 from ME, 1,047 from LRT and 173 from IPD. Carriage rates remained unchanged between the study periods (67.3% vs. 61.5%; p=0.090). The total number of ME samples and pneumococci isolated from ME and LRT samples decreased PostVac. Overall, VTs decreased PostVac in nasopharyngeal, ME and LRT samples (p<0.001, all sample groups), with a concurrent increase in NVTs in nasopharyngeal and ME samples (p<0.001, both) and LRT samples from adults 18-64 years old (p=0.008). Serotype 23B replaced serotype 23F as the most prevalent serotype in carriage PostVac (from 0.7/1,000 samples PreVac to 49.3 PostVac; p<0.001). Serotype 19F was the most prevalent serotype in both study periods in ME but decreased PostVac: ME from 80.7 isolates avg/yr PreVac to 11.2 PostVac (p<0.001). Serotype 19F was the most prevalent serotype PreVac in LRT samples but decreased from 58.2/100,000 adults PreVac to 10.7 PostVac-II (p<0.001). The majority of serotype 19F isolates were penicillin non-susceptible pneumococci (PNSP) and multidrug resistant (MDR). All PNSP/MDR serotype 19F isolates were members of CC236/271/32019F, variants of the international MDR Taiwan19F-14 lineage. Serotype 23B had a predilection for carriage and serotype 19F for the middle ear. Serotype 6C increased overall between the periods in carriage (from 6.5/1,000 samples to 49.0; p<0.001), ME (from 0.3 isolates avg/yr to 6.8; p<0.001) and LRT samples (from 0.6/100,000 adults to 7.5; p=0.021). A large number of serotype 6C were PNSP and MDR. NVT serotypes that increased significantly PostVac in nasopharyngeal and ME samples from children in different age strata were: 15A, 15B/C, 21, 22F, 23A, 35F and 35B. Non-encapsulated isolates were the most prevalent pneumococci overall in LRT samples PostVac and increased in adults 18-64 years of age (from 4.2/100,000 adults 18-64 years PreVac to 16.2 PostVac-II; p=0.028). The majority were PNSP and MDR. The study revealed that carriage rates were similar in both study periods. The annual number of ME samples and pneumococcal-positive cultures in ME and LRT samples decreased following PHiD-CV implementation. Significant shifts in serotype distribution followed vaccination where VTs decreased and were replaced by NVTs. Herd effect was seen within the older unvaccinated population within four years of vaccine introduction. Isolates of the MDR CC236/271/32019F have nearly been eliminated after vaccine introduction. Whether this lineage will be replaced by other MDR lineages, such as CC3156C, remains to be seen.Pneumókokkar eru mikilvægir sýkingavaldar í mönnum. Heilbrigð börn á leikskólaaldri geta borið pneumókokka í nefkoki án nokkurra einkenna en pneumókokkar geta leitt til miðeyrnasýkingar, lungnabólgu og ífarandi sýkinga. Bólusetning með próteintengdum bóluefnum leiðir til fækkunar stofna af hjúpgerðum sem bóluefnið veitir vörn gegn (bóluefnis hjúpgerð, e. vaccine type: VT) en getur auk þess leitt til fjölgunar stofna af hjúpgerðum sem bóluefnið veitir ekki vörn gegn (ekki bóluefnis hjúpgerð, e. non-vaccine type: NVT). Tíu-gilda próteintengda pneumókokka bóluefnið (PHiD-CV, GSK) var innleitt í ungbarnabólusetningar á Íslandi árið 2011. Markmið rannsóknarinnar var að meta áhrif PHiD-CV á pneumókokka sem ræktaðir voru úr nefkoki heilbrigðra leikskólabarna, miðeyrum (ME) barna með miðeyrnarbólgu og neðri öndunarvegum (LRT) fullorðinna einstaklinga með grun um lungnabólgu. Í rannsókninni var dreifing hjúpgerða, raðgerða (e. sequence types, ST) og sýklalyfjanæmi pneumókokkastofna fundið. Gögn fyrir bólusetningu (2009-2011) voru borin saman við gögn eftir bólusetningu (2012-2017). Nefkoksstrokum var safnað árlega (í mars, 2009-2017) frá börnum <7 ára frá 15 mismunandi leikskólum á stór-höfuðborgarsvæðinu. Allir pneumókokkastofnar sem ræktuðust frá ME barna <7 ára á Landspítala Háskólasjúkrahúsi árin 2009-2017 voru greindir. Til að leiðrétta fyrir mismunandi fjölda ára fyrir og eftir bólusetningu var meðalfjöldi ME stofna á ári skoðaðir á hverju tímabili fyrir sig. Öll sýni frá LRT fullorðinna ≥18 ára voru með í rannsókninni. Pneumókokkastofnum frá LRT eftir bólusetningu var skipt í tvö tímabil: eftir-I (2012-2014) og eftir-II (2015-2017). Allir stofnar voru hjúpgreindir með latex kekkjun og/eða PCR og/eða hjúpgerðin fengin úr raðgreiningargögnum. Sýklalyfjanæmi stofna var mælt og túlkað samkvæmt EUCAST staðli. Annar hver stofn frá árunum 2009-2014 var heilraðgreindur. ST voru fengnar úr raðgreiningargögnunum og þeim raðað í klónal komplexa (CC). Skyldleikatré voru gerð og lituð með tilliti til hjúpgerða og CC. Tveggjaþátta Fisher´s exact próf var notað til að reikna p-gildi og marktækni var miðuð við p ≤0,05. Alls voru 5570 stofnar rannsakaðir yfir allt tímabilið: 3020 frá nefkoki, 1330 frá ME, 1047 frá LRT og 173 úr ífarandi sýkingum. Berahlutfall leikskólabarna var óbreytt milli tímabilanna tveggja (fyrir 67,3% og eftir 61,5%; p=0,090). Sýnum frá ME fækkaði eftir bólusetningu og jafnframt fjöldi pneumókokkaræktanna frá ME og LRT. Pneumókokkastofnum af VT hjúpgerðum fækkaði í öllum sýnaflokkum milli tímabilanna (p<0,001, allir sýnaflokkar) með samhliða fjölgun á pneumókokkastofnum af NVT hjúpgerðum í sýnum frá berum, ME (p<0,001, báðir sýnaflokkar) og LRT frá fullorðnum 18-64 ára (p=0,008). Hjúpgerð 23B tók við af hjúpgerð 23F sem algengasta hjúpgerðin í berasýnum eftir bólusetningu (úr 0,7/1000 sýni fyrir bólusetningu í 49,3 eftir; p<0,001). Stofnar af hjúpgerð 19F voru algengastir bæði tímabilin í ME en fækkaði úr 80,7 á ári fyrir bólusetningu í 11,2 eftir (p<0,001). Stofnar af hjúpgerð 19F voru algengastir fyrir bólusetningu í LRT en fækkaði úr 58,2/100000 fullorðnir fyrir bólusetningu í 10,7 eftir-II (p<0,001). Meirihluti stofna af hjúpgerð 19F var með minnkað næmi fyrir penisillíni (PNSP) og voru fjölónæmir (MDR). Allir PNSP/MDR stofnar af hjúpgerð 19F tilheyrðu CC236/271/32019F, afbrigði af alþjóðlega MDR Taiwan19F -14 klóninum. Hjúpgerð 23B var oftar í nefkoki heilbrigðra leikskólabarna en hjúpgerð 19F sýkti oftar miðeyru barna. Stofnum af hjúpgerð 6C fjölgaði í heildina milli tímabilanna í sýnum frá berum (úr 6,5/1000 sýni fyrir bólusetningu í 49,0 eftir; p<0,001), ME (úr 0,3 á ári fyrir í 6,8 eftir; p<0,001) og LRT (úr 0,6/100000 fullorðnir fyrir í 7,5 eftir-II; p=0,021). Stór hluti stofna af hjúpgerð 6C var PNSP og MDR. Stofnum af öðrum NVT hjúpgerðum sem fjölgaði marktækt eftir bólusetningu í sýnum frá berum og ME meðal barna á mismunandi aldri voru: 15A, 15B/C, 21, 22F, 23A, 35F og 35B. Hjúplausir pneumókokkar voru algengastir eftir bólusetningu í sýnum frá LRT og hjúplausum pneumókokkastofnum fjölgaði í aldurshópi 18-64 ára (úr 4,2/100000 18-64 ára fyrir bólusetningu í 16,2 eftir-II; p=0,028). Meirihluti hjúplausra stofna voru PNSP og MDR. Niðurstöður rannsóknarinnar sýna að berahlutfall var svipað milli rannsóknartímabilanna. Árlegur fjöldi ME sýna og fjöldi pneumókokkaræktana frá ME og LRT sýnum lækkaði eftir innleiðingu PHiDCV. Marktækar breytingar urðu á dreifingu hjúpgerða eftir bólusetningu þar sem stofnum af VT hjúpgerðum fækkaði og í staðinn komu stofnar af NVT hjúpgerðum. Hjarðónæmi hjá eldri óbólusettum einstaklingum var sýnilegt innan fjögurra ára frá innleiðingu bóluefnisins. Stofnar af CC236/271/32019F hafa nánast horfið eftir bólusetningu. Hvort að aðrir MDR klónar, eins og CC3156C, komi í staðinn á eftir að koma í ljós

Dreifing hjúpgerða pneumókokka í sýkingum 0-6 ára barna árið 2010

Streptococcus pneumoniae, pneumókokkar, eru mikilvægir sýkingavaldar í mönnum um allan heim, þó sérstaklega í börnum undir fimm ára aldri og rosknu fólki. Þeir eru meðal algengustu orsaka miðeyrnabólgu og lungnabólgu sem og ífarandi sýkinga eins og blóðsýkinga og heilahimnubólgu. Eiginleikar fjölsykruhjúpsins gera hann að helsta meinvikniþætti pneumókokka og er mikilvægasta hlutverk hans að verja bakteríuna fyrir varnarkerfi hýsilsins. Hæfni pneumókokka til að valda ífarandi sýkingum er mismikil milli hjúpgerða en tiltölulega fáar hjúpgerðir af þeim 93 sem þekktar eru, eru orsök meiri hluta ífarandi sýkinga. Dreifing hjúpgerða pneumókokka er breytileg eftir landsvæðum, aldri og tímabilum en eiginleikar klóna sem eru í umferð hverju sinni gefa þeim forskot sem gæti stuðlað að breytinum á dreifingu hjúpgerða t.d. hæfileikar til að valda ífarandi sýkingum og myndun ónæmis fyrir algengum sýklalyfjum. Hér á landi höfum við á um tveim áratugum séð klón af hjúpgerð 6B sem er fjölónæmur fyrir sýklalyfjum ná fótfestu, dreifast um samfélagið og hverfa síðan nánast alveg og síðan annan klón sem einnig er fjölónæmur af hjúpgerð 19F gera slíkt hið sama, en hann er enn í útbreiðslu. Í apríl á þessu ári hófst bólusetning með bóluefninu Synflorix á Íslandi gegn tíu hjúpgerðum pneumókokka. Bóluefnið stendur öllum börnum sem fæðast frá og með 1. janúar 2011 til boða. Þegar áhrif bólusetninga eru metin þarf fyrst að liggja fyrir dreifing hjúpgerða pneumókokka í sýkingum og hjá heilbrigðum berum áður en þær hefjast og helst um nokkurn tíma þannig að náttúrulegar tímasveiflur sjáist. Með áframhaldandi eftirliti með dreifingu hjúpgerða er þá hægt að meta hvort og þá hvaða hjúpgerðir koma í stað þeirra sem bóluefnið veitir vörn gegn. Markmið þessarar forkönnunar er að setja upp multiplex PCR aðferð sem hjúpgreinir marga pneumókokkastofna í senn á sérvirkan og hlutlægan hátt og meta vaxandi (cumulative) hlutfall hjúpgerða pneumókokka sem greinast í multiplex PCR hvörfum. Jafnframt er markmiðið að kanna dreifingu hjúpgerða pneumókokka í sjúklingasýnum frá 0-6 ára börnum frá árinu 2010. Í sýnum frá augum, miðeyra og nefkoki ræktuðust 602 stofnar frá 0-6 ára börnum sem voru ræktaðir og greindir með hefðbundnum aðferðum á Sýklafræðideild Landspítalans árið 2010. Þegar var búið að full hjúpgreina 134 stofna með Latex taflborðskekkjunarprófi og kóagglútínasjónprófi og jafnframt var búið að greina hjúpgerðarhóp 87 stofna. Fjögur multiplex PCR hvörf voru sett upp í panel til að greina 12 hjúpgerðir pneumókokka í 386 sýnum. Í fyrsta hvarfinu voru prímerar fyrir þrjár algengustu hjúpgerðir pneumókokka sem greindust árið 2005-2007 í rannsókn Mörthu Á. Hjálmarsdóttur og félaga, í öðru hvarfi voru næstu þrjár algengustu og svo koll af kolli. Multiplex PCR aðferðin greindi 44% hjúpgerða pneumókokka í fyrsta hvarfi en í heildina greindust 61,9% hjúpgerðir pneumókokka með multiplex PCR aðferðinni. Jafnframt greindist fyrsta tilfelli af hjúpgerð 6D á Íslandi í þessari rannsókn. Algengustu hjúpgerðir pneumókokka sem greindust í sýnum frá 0-6 ára börnum árið 2010 voru 19F (39,1%), 6A (9,8%), 23F (9,0%), 19A (4,0%) og 14 (3,7%). Hjúpgerð 19F var algengust í öllum sýnaflokkum hjá 0-1 árs börnum og hjá 2-6 ára börnum. Hjúpgerð 23F var næst algengust bæði í sýnum frá augum og miðeyra en hjúpgerð 6A í sýnum frá nefkoki. Jafnframt var hjúpgerð 23F næst algengust hjá yngri börnunum en hjúpgerð 6A hjá eldri börnunum. Rannsóknin sýndi að multiplex PCR aðferðin virkar vel og er hentug til að greina stór stofnastöfn. Jafnframt sýndi rannsóknin að aðferðin getur greint allt að 2/3 pneumókokkastofna í fyrsta multiplex PCR hvarfinu

Comparison of Serotype Prevalence of Pneumococci Isolated from Middle Ear, Lower Respiratory Tract and Invasive Disease Prior to Vaccination in Iceland.

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).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.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

Ranking of the eight most common serotypes according to infection site and their proportions (%) and of VTs and NVTs according to sampling site.

<p>Ranking of the eight most common serotypes according to infection site and their proportions (%) and of VTs and NVTs according to sampling site.</p

Distribution of all isolates and PNSP isolates according to sampling site and age of the patient and their proportions (%) within age group and sampling site.

<p>Distribution of all isolates and PNSP isolates according to sampling site and age of the patient and their proportions (%) within age group and sampling site.</p

Ranking of the 4 most common PNSP serotypes according to sampling site.

<p>Ranking of the 4 most common PNSP serotypes according to sampling site.</p