Publications by authors named "Didrik F Vestrheim"

27 Publications

  • Page 1 of 1

Antimicrobial susceptibility and clonality of Streptococcus pneumoniae isolates recovered from invasive disease cases during a period with changes in pneumococcal childhood vaccination, Norway, 2004-2016.

Vaccine 2020 07 30;38(34):5454-5463. Epub 2020 Jun 30.

Department of Infection Control and Vaccines, Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway. Electronic address:

Changes in pneumococcal antimicrobial resistance (AMR) have been reported following use of pneumococcal conjugate vaccines (PCVs) in childhood vaccination programmes. We describe AMR trends and clonality in Norway during 2004-2016; we studied 10,239 invasive pneumococcal disease (IPD) isolates in terms of serotypes, antimicrobial susceptibility, and for a systematically collected subset of 2473 isolates, multilocus sequence types (ST). The IPD cases were notified to the Norwegian Surveillance System for Communicable Diseases and pneumococcal isolates were collected through the National Reference Laboratory for Pneumococci. The cases are sourced from the entire Norwegian population. We supplemented the IPD isolates with isolates from carriage studies in children attending day-care, performed in 2006 (before mass childhood vaccination with PCV7), 2008 (2 years after PCV7 introduction), 2013 (2 years after the transition to PCV13), and 2015. IPD cases were 0-102 years old; median 64 years. Carriage study participants were typically aged 1-5 years. Overall, AMR was low; a maximum of 7% of IPD isolates were resistant, depending on the antimicrobial. Erythromycin and trimethoprim/sulfamethoxazole resistant IPD (ERY-R and SXT-R, respectively) decreased in the PCV7 period (2006-2010). In the PCV13 period (2011-2016) however, we saw an indication of increased non-susceptibility among IPD isolates. This increase was mainly due to non-vaccine serotypes 15A-ST63 (multidrug resistant), 24F-ST162 (SXT-R), 23B-ST2372 (penicillin non-susceptible and SXT-R) and 33F (ERY-R and clindamycin resistant). Resistant or non-susceptible IPD isolates were often clones introduced into Norway during the study period. The exception was ERY-R isolates; initially, these largely consisted of an established serotype 14-ST9 clone, which disappeared after introducing PCV7. The carriage study results mostly resembled the changes seen in IPD with a maximum of 9% of the participants per study carrying resistant pneumococci. As actual PCVs are not fully limiting AMR, higher-valency vaccines and prudent use of antimicrobials are still needed to temper pneumococcal AMR.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.vaccine.2020.06.040DOI Listing
July 2020

High overall confidence in childhood vaccination in Norway, slightly lower among the unemployed and those with a lower level of education.

Vaccine 2020 06 21;38(29):4536-4541. Epub 2020 May 21.

Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway.

In Norway, childhood immunisation is offered on voluntary basis, free of charge and is delivered through trained nurses at > 650 child health centres and school health services. Maintaining high confidence in the vaccination programme is key to sustaining high vaccine uptake. We aimed to investigate confidence in childhood vaccination in the general population and to identify determinants for lower confidence. In 2017 and 2018, Statistics Norway asked questions on confidence in childhood vaccination (to all respondents) and children's vaccination history (to parents) in their routine cross-sectional survey. Respondents reported their level of agreement on a five-point Likert scale. Using a weighted analysis we calculated proportions agreeing [95% confidence interval] by respondent characteristics. Overall, 2169 individuals participated (54% response). 95.8% [94.8-96.7] answered that vaccination is important, 93.4% [92.2-94.4] thought that vaccines are safe, 96.0% [95.0-96.8] thought that vaccines are effective and for 93.4% [92.2-94.4] vaccination was compatible with their basic values. Those with lower level of education expressed lower confidence in vaccination due to conflict with their basic values (88.2% [84.7-91.0] answered positively). Those unemployed expressed lower confidence due to conflict with their basic values (81.9% [71.8-88.9]) and because of concerns about vaccines' safety (83.5% [73.7-90.1]). 96.3% [94.3-97.6] of parents (n = 580) had their children fully vaccinated, despite that one fifth answered that they at least once have had doubts on whether or not to vaccinate their children. There is high confidence in childhood vaccination in Norway. Those with a lower level of education and the unemployed reported comparatively lower confidence. To maintain high confidence in childhood vaccination, we recommend maintaining the well-informed system with easily accessible vaccinations. Furthermore, we recommend maintaining surveillance of vaccine confidence, supplemented with targeted studies on subgroups who are less confident, express doubts and/or oppose vaccination. Those studies should inform communication strategies tailored to subgroups.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.vaccine.2020.05.011DOI Listing
June 2020

Impact of narrow-spectrum penicillin V on the oral and faecal resistome in a young child treated for otitis media.

J Glob Antimicrob Resist 2020 03 12;20:290-297. Epub 2019 Aug 12.

Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway. Electronic address:

Objectives: Antibiotic overuse has led to the global emergence of antimicrobial-resistant bacteria, and children are among the most frequent users of antibiotics. Most studies with broad-spectrum antibiotics show a severe impact on resistome development in patients. Although narrow-spectrum antibiotics are believed to have fewer side effects, their impact on the microbiome and resistome is mostly unknown. The aim of this study was to investigate the impact of the narrow-spectrum antibiotic phenoxymethylpenicillin (penicillin V) on the microbiome and resistome of a child treated for acute otitis media.

Methods: Oral and faecal samples were collected from a 1-year-old child before (Day 0) and after (Days 5 and 30) receiving penicillin V for otitis media. Metagenomic sequencing data were analysed to determine taxonomic profiling using Kraken and Bracken software, and resistance profiling using KMA in combination with the ResFinder database.

Results: In the oral samples, antimicrobial resistance genes (ARGs) belonging to four classes were identified at baseline. At Day 5, the abundance of some ARGs was increased, whereas some remained unchanged and others could no longer be detected. At Day 30, most ARGs had returned to baseline levels or lower. In the faecal samples, seven ARGs were observed at baseline and five at Day 5. At Day 30, the number of ARGs had increased to 21.

Conclusions: Following penicillin V, we observed a remarkable enrichment of the aecal resistome, indicating that even narrow-spectrum antibiotics may have important consequences in selecting for a more resistant microbiome.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jgar.2019.08.004DOI Listing
March 2020

Indirect Effects of Pneumococcal Childhood Vaccination in Individuals Treated With Immunosuppressive Drugs in Ambulatory Care: A Case-cohort Study.

Clin Infect Dis 2019 04;68(8):1367-1373

Department of Vaccine Preventable Diseases, Norwegian Institute of Public Health.

Background: The extent to which iatrogenically-immunosuppressed individuals benefit from indirect effects of childhood vaccination with pneumococcal conjugate vaccines (PCVs) is unknown. We determined how the sequential introduction of PCV7 (2006) and PCV13 (2011) in the Norwegian childhood vaccination program has affected the epidemiology of invasive pneumococcal disease (IPD) in individuals treated with immunosuppressants in ambulatory care.

Methods: We conducted a case-cohort study comprising 7926 IPD cases reported to the Norwegian Surveillance System for Communicable Diseases in 2005-2014 and 249998 individuals randomly selected from the National Registry in 2012. We defined immunosuppressive treatment groups based on dispensed prescriptions retrieved from the Norwegian Prescription Database. Incidences and age-adjusted relative risks (RR) were estimated.

Results: IPD incidences decreased in all groups. The PCV13 incidence decreased by 5-12% across groups. The non-PCV13 incidence increased by 4-10%, mostly in individuals on chemotherapy (overlapping 95% confidence intervals). In the PCV13 era, the RR for IPD was highest (significant) and the percentage of cases caused by the polysaccharide vaccine PPV23 serotypes lowest (numerical) in individuals on chemotherapy (RR = 20.4, PPV23 = 52%), followed by individuals on corticosteroids (RR = 6.2, PPV23 = 64%), other immunosuppressants (RR = 5.6, PPV23 = 68%), and no immunosuppressants (RR = 1 [reference], PPV23 = 74%).

Conclusions: IPD incidences declined after PCV introduction in both immunocompetent and iatrogenically-immunosuppressed individuals, underscoring the benefit of childhood vaccination for the entire population. Still, individuals treated with immunosuppressants in ambulatory care are at increased risk of IPD caused by a more diverse group of serotypes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/cid/ciy714DOI Listing
April 2019

Effect of childhood pneumococcal conjugate vaccination on invasive disease in older adults of 10 European countries: implications for adult vaccination.

Thorax 2019 05 24;74(5):473-482. Epub 2018 Oct 24.

EpiConcept, Paris, France.

Background: Pneumococcal conjugate vaccines (PCVs) have the potential to prevent pneumococcal disease through direct and indirect protection. This multicentre European study estimated the indirect effects of 5-year childhood PCV10 and/or PCV13 programmes on invasive pneumococcal disease (IPD) in older adults across 13 sites in 10 European countries, to support decision-making on pneumococcal vaccination policies.

Methods: For each site we calculated IPD incidence rate ratios (IRR) in people aged ≥65 years by serotype for each PCV10/13 year (2011-2015) compared with 2009 (pre-PCV10/13). We calculated pooled IRR and 95% CI using random-effects meta-analysis and PCV10/13 effect as (1 - IRR)*100.

Results: After five PCV10/13 years, the incidence of IPD caused by all types, PCV7 and additional PCV13 serotypes declined 9% (95% CI -4% to 19%), 77% (95% CI 67% to 84%) and 38% (95% CI 19% to 53%), respectively, while the incidence of non-PCV13 serotypes increased 63% (95% CI 39% to 91%). The incidence of serotypes included in PCV13 and not in PCV10 decreased 37% (95% CI 22% to 50%) in six PCV13 sites and increased by 50% (95% CI -8% to 146%) in the four sites using PCV10 (alone or with PCV13). In 2015, PCV13 serotypes represented 20-29% and 32-53% of IPD cases in PCV13 and PCV10 sites, respectively.

Conclusion: Overall IPD incidence in older adults decreased moderately after five childhood PCV10/13 years in 13 European sites. Large declines in PCV10/13 serotype IPD, due to the indirect effect of childhood vaccination, were countered by increases in non-PCV13 IPD, but these declines varied according to the childhood vaccine used. Decision-making on pneumococcal vaccination for older adults must consider the indirect effects of childhood PCV programmes. Sustained monitoring of IPD epidemiology is imperative.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/thoraxjnl-2018-211767DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6484683PMC
May 2019

Draft Genome Sequence of a Potentially Novel Streptococcus Species Belonging to the Streptococcus mitis Group.

Genome Announc 2018 Jun 28;6(26). Epub 2018 Jun 28.

Division of Infection Control and Environmental Sciences, Norwegian Institute of Public Health, Oslo, Norway

We report here the draft genome sequence of a species belonging to the group. While a clear species identification cannot be made for the isolate, it appears that its most recent common ancestor is the species .
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/genomeA.00620-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6025937PMC
June 2018

Surveillance of Circulating Bordetella pertussis Strains in Europe during 1998 to 2015.

J Clin Microbiol 2018 05 25;56(5). Epub 2018 Apr 25.

Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland

One reason for increased pertussis incidence is the adaptation of to vaccine-induced immunity by modulating its genomic structure. This study, EUpert IV, includes 265 isolates collected from nine European countries during 2012 to 2015 ( = 265) and compares the results to previous EUpert I to III studies (1998 to 2009). The analyses included genotyping, serotyping, pulsed-field gel electrophoresis (PFGE), and multilocus variable-number tandem-repeat analysis (MLVA). Genotyping results showed only small variations among the common virulence genes of The frequencies of serotypes Fim2 and Fim3 varied among the four collections. Genomic analyses showed that MLVA type 27 increased to 80% between the periods of 1998 to 2001 and 2012 to 2015. Two PFGE profiles, BpSR3 (29.4%) and BpSR10 (27.2%), constituted more than 50% of the circulating isolates in the present collection. Our study indicates that the European population is changing and became more homogenous after the introduction of acellular pertussis vaccines.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/JCM.01998-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5925733PMC
May 2018

External Quality Assurance for Laboratory Identification and Capsular Typing of Streptococcus pneumoniae.

Sci Rep 2017 10 16;7(1):13280. Epub 2017 Oct 16.

Department of vaccine preventable diseases, Norwegian Institute of Public Health, Oslo, Norway.

An external quality assessment (EQA) scheme for pneumococcal serotype identification has been performed over a period of 11 years, by a network of European pneumococcal reference laboratories. We report the results from the EQA, and present an assessment of the acceptability and utility of the EQA scheme. Reports from 22 EQA panels distributed in 2005-2016 were analysed. Each EQA panel consisted of seven isolates. A questionnaire including seven questions related to the acceptability and utility of the EQA scheme was distributed to all participating laboratories. Altogether, 154 pneumococcal isolates were tested. Of the 92 serologically distinct serotypes currently defined, 49 serotypes were included in the rounds. Discrepant results were observed in eight EQA rounds, involving 11 isolates (7.1%, 95% CI: 4% to 12%). All participating laboratories reported that the EQA scheme was useful for quality assurance purposes. Our results show that comparable serotyping data can be obtained in different laboratories. The EQA participation helps to keep the typing procedures at a high standard and provides data for accreditation purposes. The EQA is helpful when new technologies are introduced, and reveal limitations of both genotypic and phenotypic methods. Continuation of the presented EQA scheme is planned.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-017-13605-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5643306PMC
October 2017

HPV-vaksinene gir god beskyttelse.

Tidsskr Nor Laegeforen 2017 08 21;137(14-15). Epub 2017 Aug 21.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4045/tidsskr.17.0585DOI Listing
August 2017

Effect of high-valency pneumococcal conjugate vaccines on invasive pneumococcal disease in children in SpIDnet countries: an observational multicentre study.

Lancet Respir Med 2017 08 27;5(8):648-656. Epub 2017 Mar 27.

Epidemiology Department, EpiConcept, Paris, France.

Background: The Streptococcus pneumoniae Invasive Disease network (SpIDnet) actively monitors populations in nine sites in seven European countries for invasive pneumococcal disease. Five sites use 13-valent pneumococcal conjugate vaccine (PCV13) alone and four use the ten-valent PCV (PCV10) and PCV13. Vaccination uptake is greater than 90% in six sites and 67-78% in three sites. We measured the effects of introducing high-valency PCVs on the incidence of invasive pneumococcal disease in children younger than 5 years.

Methods: We compared the incidence of invasive pneumococcal disease in each of the 4 years after the introduction of PCV13 alone or PCV10 and PCV13 with the average incidence during the preceding period of heptavalent PCV (PCV7) use, overall and by serotype category. We calculated incidence rate ratios (IRRs) and 95% CIs for each year and pooled the values for all sites in a random effects meta-analysis.

Findings: 4 years after the introduction of PCV13 alone or PCV10 and PCV13, the pooled IRR was 0·53 (95% CI 0·43-0·65) for invasive pneumococcal disease in children younger than 5 years caused by any serotype, 0·16 (0·07-0·40) for disease caused by PCV7 serotypes, 0·17 (0·07-0·42) for disease caused by 1, 5, and 7F serotypes, and 0·41 (0·25-0·69) for that caused by 3, 6A and 19A serotypes. We saw a similar pattern when we restricted the analysis to sites where only PCV13 was used. The pooled IRR for invasive pneumococcal disease caused by non-PCV13 serotypes was 1·62 (1·09-2·42).

Interpretation: The incidence of invasive pneumococcal disease caused by all serotypes decreased due to a decline in the incidence of vaccine serotypes. By contrast, that of invasive pneumococcal disease caused by non-PCV13 serotypes increased, which suggests serotype replacement. Long-term surveillance will be crucial to monitor the further effects of PCV10 and PCV13 vaccination programmes in young children.

Funding: European Centre for Disease Prevention and Control, Czech National Institute of Public Health, French National Agency for Public Health, Irish Health Services Executive, Norwegian Institute of Public Health, Public Health Agency of Catalonia, Public Health Department of Community of Madrid, Navarra Hospital Complex, Public Health Institute of Navarra, CIBER Epidemiology and Public Health, Institute of Health Carlos III, Public Health Agency of Sweden, and NHS Scotland.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/S2213-2600(17)30110-8DOI Listing
August 2017

In vitro and in vivo comparison of transport media for detecting nasopharyngeal carriage of Streptococcus pneumoniae.

PeerJ 2016 22;4:e2449. Epub 2016 Sep 22.

Infection Control and Environmental Health, Norwegian Institute of Public Health , Oslo , Norway.

Background: As a standard method for pneumococcal carriage studies, the World Health Organization recommends nasopharyngeal swabs be transported and stored at cool temperatures in a medium containing skim-milk, tryptone, glucose and glycerol (STGG). An enrichment broth used for transport at room temperature in three carriage studies performed in Norway may have a higher sensitivity than STGG. We therefore compared the media in vitro and in vivo.

Methods: For the in vitro component, three strains (serotype 4, 19F and 3) were suspended in STGG and enrichment broth. Recovery was compared using latex agglutination, quantification of bacterial loads by real-time PCR of the lytA gene, and counting colonies from incubated plates. For the in vivo comparison, paired swabs were obtained from 100 children and transported in STGG at cool temperatures or in enrichment broth at room temperature. Carriage was identified by latex agglutination and confirmed by Quellung reaction.

Results: In vitro, the cycle threshold values obtained by PCR did not differ between the two media (p = 0.853) and no clear difference in colony counts was apparent after incubation (p = 0.593). In vivo, pneumococci were recovered in 46% of swabs transported in STGG and 51% of those transported in enrichment broth (Kappa statistic 0.90, p = 0.063).

Discussion: Overall, no statistical differences in sensitivity were found between STGG and enrichment broth. Nevertheless, some serotype differences were observed and STGG appeared slightly less sensitive than enrichment broth for detection of nasopharyngeal carriage of pneumococci by culturing. We recommend the continued use of STGG for transport and storage of nasopharyngeal swabs in pneumococcal carriage studies for the benefit of comparability between studies and settings, including more resource-limited settings.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5036082PMC
http://dx.doi.org/10.7717/peerj.2449DOI Listing
October 2016

Epidemiology and outcome of sepsis in adult patients with Streptococcus pneumoniae infection in a Norwegian county 1993-2011: an observational study.

BMC Infect Dis 2016 05 23;16:223. Epub 2016 May 23.

Clinic of Anaesthesia and Intensive Care, St Olav University Hospital, Trondheim, Norway.

Background: Invasive pneumococcal disease (IPD) is responsible for significant mortality and morbidity worldwide. There are however few longitudinal studies on the changes in case fatality rate of IPD in recent years. We carried out a prospective observational study of patients with IPD in Nord Trøndelag county in Norway from 1993 to 2011 to study the clinical variables and disease outcome. The main outcome was all-cause mortality after 30 and 90 days.

Methods: Patients with positive blood cultures were registered prospectively by the microbiology laboratory and clinical variables were registered retrospectively from patients' hospital records. The severity of sepsis was assigned according to the 2001 International Sepsis Definition Conference criteria. The association between mortality and predictive factors was studied using a logistic regression model.

Results: The total number of patients was 414 with mean age of 67 years and 53 % were male. Comorbidity was assessed by the Charlson Comorbidity Index (CCI). A CCI-score of 0 was registered in 144 patients (34.8 %), whereas 190 had a score of 1-2 (45.9 %) and 80 (19.3 %) had a score ≥3. 68.8 % of the patients received appropriate antibiotics within the first 6 h. The 30-day mortality risk increased by age and was 3-fold higher for patients aged ≥80 years (24.9, 95 % CI 16.4-33.4 %) compared to patients aged <70 (8.0, 95 % CI 3.5-12.4 %). 110 patients, (26.6 %) had severe sepsis and 37 (8.9 %) had septic shock. The 30 day all-cause mortality risk for those with sepsis without organ failure was 5.4 % (95 % CI 2.7-8.0 %), 20.2 % (95 % CI 13.5-27.4 %) for those with severe sepsis and 35.0 % (95 % CI 21.6-49.0 %) for those with septic shock. The mortality risk did not differ between the first and the second halves of the study period with a 30-day mortality risk of 13.5 % (95 % CI 7.9-19.2 %) for 1993-2002 versus 11.8 % (95 % CI 8.2-15.3 %) for 2003-2011.

Conclusion: IPD carries a high mortality despite early and appropriate antibiotics in most cases. We found no substantial decrease in case fatality rate during the study period of 18 years. Older age and higher severity of disease were important risk factors for death in IPD.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12879-016-1553-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4877975PMC
May 2016

Geographical differences in seroprevalence of Borrelia burgdorferi antibodies in Norway, 2011-2013.

Ticks Tick Borne Dis 2016 07 27;7(5):698-702. Epub 2016 Feb 27.

Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway.

Detection of specific antibodies against Borrelia burgdorferi sensu lato is a useful aid for the diagnosis of Lyme borreliosis. However, antibodies are present in the general population. The seroprevalence increase with age, and varies according to the prevalence of infected ticks. We performed a seroprevalence study of IgM and IgG antibody reactivity against B. burgdorferi sensu lato in Norway by age-groups and geography, in order to provide a reference set of seroprevalence to inform the interpretation of positive test results. We used two commercially available enzyme immuno assays (EIA) and a multiplexed bead assay to detect Borrelia IgG antibodies in a convenience sample of 3057 sera collected from clinical chemistry laboratories in 10 of 19 counties in Norway between December 2011 and January 2013. We estimated seroprevalence by age and county by a logistic regression model. IgM antibodies were detected by two commercially available EIAs and a multiplexed bead assay. The overall seroprevalence of Borrelia IgG was 4.0% (95% CI: 2.4-6.6%) and 4.2% (2.6-6.8%) by the two EIAs, respectively. The seroprevalence increased by age, and by geography from north to south. The IgG assays showed a good agreement for positive test results. All sera positive for IgG in the multiplexed bead assay reacted with the VlsE antigen, and also had high antibody levels by EIA. The Borrelia seroprevalence varied by geography and increased by age. The results indicate regional differences in pre-test probabilities for positive test results, and can inform the interpretation of laboratory results.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ttbdis.2016.02.020DOI Listing
July 2016

Decreased Carriage and Genetic Shifts in the Streptococcus pneumoniae Population After Changing the Seven-valent to the Thirteen-valent Pneumococcal Vaccine in Norway.

Pediatr Infect Dis J 2015 Aug;34(8):875-83

From the *Division of Infectious Disease Control, Department of Bacteriology and Immunology, Norwegian Institute of Public Health, Oslo, Norway; †Faculty of Medicine, University of Oslo, Oslo, Norway; and ‡European Programme for Public Health Microbiology Training (EUPHEM), European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden.

Background: Shifts in the pneumococcal population colonizing healthy children are expected after switching from a 7-valent pneumococcal conjugate vaccine (PCV7) to a 13-valent (PCV13) in the childhood immunization program. We assessed effects of the switch by comparing pneumococcal carriage and serotype and genetic diversity of pneumococci carried by children in the PCV13-era with those carried in the prevaccination-era and PCV7-era.

Methods: Nasopharyngeal swabs were obtained in autumn 2013 from children attending day-care centers (874 swabs, 583 isolates). Serotyping, multilocus sequence typing and antimicrobial susceptibility testing were performed on all isolates. Results were compared with samples from 2006 (610 swabs, 538 isolates) and 2008 (600 swabs, 562 isolates).

Results: The carriage prevalence in 2013 was 62 of 100 children (95% confidence intervals: 58-66), a significant decrease from 2006 and 2008. PCV13 serotypes accounted for 7% of isolates in 2013. Non-PCV13 prevalence increased from 2006 to 2008 [prevalence ratio: 1.73 (1.40-2.15)] but remained stable in 2013 [0.99 (0.88-1.12)]. Still, non-PCV13 serotypes 21, 23B, 23A and 22F had increased. In 2013, the serotype and genetic diversity had decreased slightly, and distinct serotype and genetic profiles clustered more within day-care centers compared with the earlier samples. Serotype switch was uncommon. Overall, antimicrobial resistance was limited.

Conclusions: Carriage of PCV13 serotypes has decreased without a coinciding increase in non-PCV13 serotypes. The serotype and genetic shifts among non-PCV13 serotypes suggest that a new equilibrium has not yet been reached. As the few non-PCV13 serotypes that increased have generally a lower invasive capacity than vaccine serotypes, direct and indirect protection of PCV13 on invasive pneumococcal disease can be expected to continue.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/INF.0000000000000751DOI Listing
August 2015

Pneumococcal vaccination in older adults in the era of childhood vaccination: Public health insights from a Norwegian statistical prediction study.

Epidemics 2015 Jun 19;11:24-31. Epub 2015 Jan 19.

Division of Infectious Disease Control, Norwegian Institute of Public Health, Norway; Oslo Center for Biostatistics and Epidemiology, Department of Biostatistics, Institute of Basic Medical Sciences, University of Oslo, Norway.

Two different vaccines, a 23-valent polysaccharide vaccine (PPV23) and a 13-valent conjugate vaccine (PCV13), are available for prevention of invasive pneumococcal disease (IPD) in the population aged 65 years and older (65+). The IPD epidemiology in the 65+ is undergoing change due to indirect effects of childhood immunisation. Vaccine recommendations for the 65+ must take into account these trends in epidemiology. We therefore explored the preventive potential of vaccination strategies to prevent IPD in the 65+, including PPV23, PCV13 or PCV13 + PPV23 in 2014-2019. Quasi-Poisson regression models were fitted to 2004-2014 population-wide surveillance data and used to predict incidences for vaccine-type and non-vaccine type IPD. We determined the number of people needed to be vaccinated to prevent one case per season (NNV) for each strategy and estimated the public health impact on the IPD case counts from increasing the vaccine uptake to 28-45%. Our results indicate that PCV13-IPD will decrease by 71% from 58 (95% prediction interval 55-61) cases in 2014/15 to 17 (6-52) in 2018/19 and PPV23-IPD by 32% from 168 (162-175) to 115 (49-313) cases. The NNV will increase over time for all strategies because of a decreasing vaccine-type IPD incidence. In 2018/19, the PCV13-NNV will be 5.3 times higher than the PPV23-NNV. Increasing the vaccine uptake will lead to a larger public health impact for all scenarios. Combining PCV13 and PPV23 is most effective, but the additional effect of PCV13 will decrease and is only marginal in 2018/19. Our study demonstrates the importance of increasing PPV23 uptake and of developing vaccines that confer broader immunity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.epidem.2015.01.001DOI Listing
June 2015

Prompt effect of replacing the 7-valent pneumococcal conjugate vaccine with the 13-valent vaccine on the epidemiology of invasive pneumococcal disease in Norway.

Vaccine 2013 Dec 29;31(52):6232-8. Epub 2013 Oct 29.

Division of Infectious Disease Control, Norwegian Institute of Public Health, Oslo, Norway; European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden. Electronic address:

The introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in the childhood immunisation programme in Norway in 2006 substantially decreased the incidence of vaccine-type (VT) invasive pneumococcal disease (IPD) in all age groups. Additionally, a slight increase in the non-vaccine (NVT) serotype IPD incidence (serotype replacement) was observed. After replacing PCV7 with PCV13 in 2011, a further decrease in IPD incidence is expected. However, the protection by the six additional serotypes opens new nasopharyngeal niches for colonisation, which favours conditions for serotype replacement. Close monitoring of IPD therefore remains important in order to quickly detect changes. In this observational retrospective population-based cohort study we used data notified nationally between 1 January 2004 and 31 December 2012 to determine the VT- and NVT-IPD incidences. The diversity in serotype distribution per year was analysed using the Simpson's index of diversity. Immunisation history of young children was obtained from the Norwegian Vaccination Registry to determine vaccine failure. The incidence of VT-IPD decreased in the targeted (<5 years) and non-targeted (≥5) age groups since PCV7 introduction and further decreased after the replacement with PCV13. Only two cases of vaccine failure were identified. This indicates very high effectiveness of the 2+1 schedules with PCV7 or PCV13 and suggests that non-vaccinated individuals profit through indirect protection. The decrease in incidence of PCV7-IPD in non-targeted age groups became larger in later years, indicating a lag phase for the indirect effects, and suggests that the indirect protection of PCV13 will increase in coming years. The incidence of some NVT, specifically serotypes 23B and 15A, increased after PCV13 introduction. This coincided with an increased Simpson's index of diversity in the targeted age group. As this suggests that serotype replacement is again occurring, continues monitoring of IPD is important so that adaptations to vaccine recommendations can be promptly issued.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.vaccine.2013.10.032DOI Listing
December 2013

Recovery of Bordetella pertussis from PCR-positive nasopharyngeal samples is dependent on bacterial load.

J Clin Microbiol 2012 Dec 3;50(12):4114-5. Epub 2012 Oct 3.

Department of Bacteriology and Immunology, Norwegian Institute of Public Health, Oslo, Norway.

Viable Bordetella pertussis isolates are essential for surveillance purposes. We performed culture of 223 PCR-positive nasopharyngeal samples. B. pertussis was recovered from 45 (20.2%) of the samples. Growth was associated with a high bacterial load, as determined by PCR. Culture from PCR-positive samples is a feasible approach to recover B. pertussis isolates, and culture can be limited to samples with a high bacterial load.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/JCM.01553-12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3502974PMC
December 2012

Decline in early childhood respiratory tract infections in the Norwegian mother and child cohort study after introduction of pneumococcal conjugate vaccination.

Pediatr Infect Dis J 2012 Sep;31(9):951-5

Department of Chronic Diseases, Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway.

Background: The 7-valent pneumococcal conjugate vaccine (PCV7) was introduced into the Norwegian Childhood Immunization Program in 2006. A substantial effectiveness of PCV7 immunization against invasive pneumococcal disease has been demonstrated, whereas evidence of its impact on respiratory tract infections are less consistent.

Methods: This study included children participating in the Norwegian Mother and Child Cohort Study, which recruited pregnant women between 1999 and 2008. Maternal report of acute otitis media (AOM), lower respiratory tract infections (LRTIs) and asthma in the child was compared by PCV7 immunization status, as obtained from the Norwegian Immunization Registry. Generalized linear models with the log-link function were used to report adjusted relative risks (RRs) and 95% confidence intervals (CIs).

Results: For children who had received 3 or more PCV7 immunizations by 12 months of age, the adjusted RRs of AOM and LRTIs between 12 and 18 months were 0.86 (95% CI: 0.81, 0.91) and 0.78 (95% CI: 0.70, 0.87) respectively, when compared with nonimmunized children. A reduced risk of AOM, RR 0.92 (95% CI: 0.90, 0.94), and LRTIs, RR 0.75 (95% CI: 0.71, 0.80), between 18 and 36 months of age was also identified among children who had received 3 or more immunizations by 18 months of age. No association was seen between PCV7 immunization and asthma at 36 months of age.

Conclusion: Reduced incidences of AOM and LRTIs before 36 months of age were observed among children immunized with PCV7 through the childhood immunization program.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/INF.0b013e31825d2f76DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3421039PMC
September 2012

Postvaccination increase in serotype 19A pneumococcal disease in Norway is driven by expansion of penicillin-susceptible strains of the ST199 complex.

Clin Vaccine Immunol 2012 Mar 11;19(3):443-5. Epub 2012 Jan 11.

Department of Bacteriology and Immunology, Norwegian Institute of Public Health, Oslo, Norway.

Serotype replacement in invasive pneumococcal disease has been observed after widespread use of the 7-valent pneumococcal conjugate vaccine (PCV7). Replacement is dominated by penicillin-nonsusceptible serotype 19A in several countries. Antibiotic selection pressure has been proposed to interact with immunization, leading to rapid replacement. In Norway, where prescription of antibiotics is limited, post-PCV7 replacement by serotype 19A is dominated by penicillin-susceptible clones. Hence, serotype 19A replacement occurs, although it is not driven by antibiotic selection pressure.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/CVI.05563-11DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3294600PMC
March 2012

Pherotypes of pneumococcal strains co-existing in healthy children.

Infect Genet Evol 2011 Oct 7;11(7):1703-8. Epub 2011 Jul 7.

Department of Bacteriology and Immunology, Norwegian Institute of Public Health, Oslo, Norway.

Genetic diversity in the species Streptococcus pneumoniae is mainly driven by horizontal gene transfer. S. pneumoniae is naturally competent for transformation. Competence is induced by a pheromone termed competence stimulating peptide (CSP) by a quorum-sensing mechanism. Two CSP pherotypes predominate amongst clinical isolates of S. pneumoniae, CSP-1 and CSP-2, with ability to trigger competence in bacteria of the homologue pherotype. Opposing theories on the effect of pherotypes on speciation have been proposed, either as a barrier for intra-pherotype gene transfer, or as a mechanism for fratricide resulting in lysis of non-competent bacterial cells. The aim of the present study was to determine pherotype distribution in strains of S. pneumococci isolated from the nasopharynges of healthy children. We sequenced the locus encoding CSP, comC, in sets of strains obtained from children colonised by multiple pneumococcal strains simultaneously. The impact of pherotype on co-colonisation was determined by comparing the observed distribution of pherotypes in co-colonising strains with the estimated pair-wise probability based on the overall pherotype distribution in the sample set. Five distinct comC alleles were identified, encoding CSP belonging to the two dominating pherotypes, CSP-1 (62.7%) and CSP-2 (37.3%). The observed distribution of pherotypes in sets of co-colonising pneumococcal strains did not differ from the probability estimate. Thus, co-colonisation of S. pneumoniae in healthy children is not restricted by pherotype.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.meegid.2011.07.003DOI Listing
October 2011

[Reduce the use of one-dose azithromycin].

Tidsskr Nor Laegeforen 2011 Apr;131(7):673-4

Olafiaklinikken, Oslo universitetssykehus, Trondheimsveien 2, 0560 Oslo, Norway.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4045/tidsskr.10.1224DOI Listing
April 2011

[Gonorrhea--time for new guidelines].

Tidsskr Nor Laegeforen 2011 Apr;131(7):671-2

Olafiaklinikken, Oslo universitetssykehus, Postboks 4763, 0506 Oslo, Norway.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4045/tidsskr.10.1380DOI Listing
April 2011

Impact of a pneumococcal conjugate vaccination program on carriage among children in Norway.

Clin Vaccine Immunol 2010 Mar 27;17(3):325-34. Epub 2010 Jan 27.

Department of Bacteriology and Immunology, Division of Infectious Disease Control, Norwegian Institute of Public Health, Nydalen, Oslo, Norway.

In July 2006, the seven-valent pneumococcal conjugate vaccine (PCV7) was introduced in Norway with a reduced (2 doses + 1 boost) dose schedule. Post-PCV7 shifts in pneumococcal reservoirs were assessed by two point prevalence studies of nasopharyngeal colonization among children in day care centers, before (2006) and after (2008) widespread use of PCV7. Nasopharyngeal swabs were obtained from 1,213 children, 611 in 2006 and 602 in 2008. A total of 1,102 pneumococcal isolates were recovered. Serotyping, multilocus sequence typing, and antimicrobial drug susceptibility testing were performed on all isolates. Although carriage of PCV7 serotypes decreased among both vaccinated and unvaccinated children, the overall prevalence of pneumococcal carriage remained high (80.4%) after vaccine introduction. The pneumococcal populations were diverse, and in the shift toward non-PCV7 serotypes, expansion of a limited number of established clonal complexes was observed. While non-antimicrobial-susceptible clones persisted among PCV7 serotypes, antimicrobial resistance did not increase among non-PCV7 serotypes. Direct and indirect protection of PCV7 against nasopharyngeal colonization was inferred from an overall decrease in carriage of PCV7 serotypes. No preference was found for nonsusceptible clones among the replacing non-PCV7 serotypes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/CVI.00435-09DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2837970PMC
March 2010

Indirect effect of conjugate pneumococcal vaccination in a 2+1 dose schedule.

Vaccine 2010 Mar 5;28(10):2214-2221. Epub 2010 Jan 5.

Division of Infectious Disease Control, Norwegian Institute of Public Health, Oslo, Norway.

In 2006, the heptavalent pneumococcal conjugate vaccine (PCV7) was introduced in the Norwegian Childhood Vaccination Programme in a 2+1 dose schedule; immunisations are administered at 3, 5 and 12 months. Changes in invasive pneumococcal disease in all ages from the baseline years 2004-2005 to 2008 were assessed, focusing on the indirect effect in the unvaccinated population. Following the introduction of PCV7, incidence rates of IPD caused by vaccine serotypes declined across all age groups, the decline being statistically significant for the age groups <5 years, 5-19 years, 40-64 years and > or = 65 years. In the unvaccinated population aged > or = 5 years the incidence rate of IPD caused by PCV7 serotypes declined by 48% from 12.34 cases/100,000 population to 6.44 cases/100,000 population, accounting for 74% of prevented cases of IPD in 2008. Among the adults aged > or = 65 years the incidence rate of IPD caused by serotypes not included in PCV7 increased. No vaccine failure was identified, indicating a very high effectiveness of the 2+1 dose schedule vaccination programme.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.vaccine.2009.12.054DOI Listing
March 2010

[Bacterial resistance against antibiotics].

Tidsskr Nor Laegeforen 2008 Nov;128(21):2452-6

Avdeling for bakteriologi og infeksjonsimmunologi Nasjonalt folkehelseinstitutt Postboks 4404 Nydalen 0403 Oslo.

Background: Antibiotic resistance has progressed over many decades and is increasingly problematic. This paper gives a short summary of antibiotic resistance and its biology.

Material And Methods: The authors have worked in this field for many years. References to major overviews and important work are given, but no systematic literature search has been done.

Results: Development of resistance is driven by positive selection of resistant clones of bacteria. There are multiple, often interlinked molecular mechanisms behind this resistance, and they all lead to a less effective interaction between antibiotics and their target.

Interpretation: Many observations of antibiotic resistance phenomena and their development over the last decades indicate that the problem is substantial, persisting and increasing. It will probably have an important impact on many medical disciplines in the future. Work to counteract this development is needed in every medical field in order to halt and hopefully counteract resistance development as strongly as we can.
View Article and Find Full Text PDF

Download full-text PDF

Source
November 2008

Phenotypic and genotypic characterization of Streptococcus pneumoniae strains colonizing children attending day-care centers in Norway.

J Clin Microbiol 2008 Aug 4;46(8):2508-18. Epub 2008 Jun 4.

Department of Bacteriology and Immunology, Division of Infectious Disease Control, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo, Norway.

A cross-sectional study of nasopharyngeal colonization with Streptococcus pneumoniae was performed among 573 children attending 29 day-care centers (DCCs) in Norway prior to the start of mass vaccination with the heptavalent pneumococcal conjugate vaccine (PCV-7). A sensitive sampling method was employed, including transport in an enrichment broth and serotyping of pneumococci directly from the broth, in addition to traditional single-colony isolation from blood agar plates. The prevalence of carriage was high, peaking at 88.7% in 2-year-olds. More than one serotype was isolated from 12.7% of the carriers. Of 509 isolates obtained, 227 (44.6%) belonged to the PCV-7 serotypes. Penicillin nonsusceptibility was rare (1.8% of the isolates). Nonsusceptibility to erythromycin (5.9%), clindamycin (2.0%), and tetracycline (5.5%) was associated with PCV-7 serotypes (P < 0.001). Multilocus sequence typing was performed on the whole strain collection, revealing 102 sequence types (STs), of which 31 (30.4%) were novel. Eleven isolates (2.2%) belonged to the England(14)-9 clone, and 19 isolates (3.7%) belonged to, or were single-locus variants of, the Portugal(19F)-21 clone. The pneumococcal populations within the DCCs were composed of a majority of isolates with STs shared between the DCCs and a minority of isolates with STs unique for each DCC. The highest numbers of different STs, including novel STs, were found within the most frequent serotypes. Our study indicates that carriage of S. pneumoniae is highly prevalent among children in Norwegian DCCs, with a genetically diverse pneumococcal population consisting of unique microepidemic DCC populations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/JCM.02296-07DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2519506PMC
August 2008

Effectiveness of a 2+1 dose schedule pneumococcal conjugate vaccination programme on invasive pneumococcal disease among children in Norway.

Vaccine 2008 Jun 18;26(26):3277-81. Epub 2008 Apr 18.

Division of Infectious Disease Control, Norwegian Institute of Public Health, Nydalen, Oslo, Norway.

The 7-valent pneumococcal conjugate vaccine (PCV-7) was licensed in Norway in 2001. In July 2006, PCV-7 was introduced in the Norwegian Childhood Vaccination Programme in a 2+1 dose schedule, with immunizations administered at 3, 5 and 12 months of age. PCV-7 was offered through the vaccination programme to all children born from January 2006, i.e. a catch-up for children aged 3-6 months. Prior to 2006 the use of PCV-7 was negligible. The effectiveness of the PCV-7 vaccination programme was assessed using data on invasive pneumococcal disease (IPD) incidence obtained from the Norwegian Surveillance System for Communicable Diseases, serotype distribution from the National Reference Laboratory for Pneumococci, and vaccine coverage and vaccination status from the Norwegian National Vaccination Register. Vaccine coverage quickly reached high levels; 95% of children >3 months born from January 2006 had received at least one immunization with PCV-7. The incidence rate of IPD among children <2 years rapidly declined; the rate of vaccine serotype IPD in this age group fell from an average of 47.1 cases/100,000 population in the 2 years prior to PCV-7 introduction to 13.7 cases/100,000 population in 2007. The incidence rate of nonvaccine serotype IPD remained stable. The vaccine programme effectiveness was estimated to be 74% (95% CI 57-85%). No vaccine failure was seen after complete primary immunization with two vaccine doses. Our findings indicate that PCV-7 provides highly effective protection against vaccine serotype IPD when administered in a 2+1 dose schedule.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.vaccine.2008.03.087DOI Listing
June 2008