Lieke Sanders, Netherlands
National Institute for Public Health and the Environment Center for Infectious DiseasesAuthor Of 5 Presentations
IMPACT OF CULTURE-ENRICHMENT ON RANKED PNEUMOCOCCAL SEROTYPE CO-PRESENCE DETERMINED USING MOLECULAR DIAGNOSTIC METHOD OF QUANTITATIVE PCR (ID 875)
Abstract
Background
We investigated impact of culture-enrichment on the rank of serotypes when detected quantitatively in nasopharyngeal samples from toddlers co-carrying multiple pneumococcal strains.
Methods
Pneumococcal serotypes were detected in nasopharyngeal swabs (collected in a cross-sectional study from children aged <5 years) using conventional culture method followed by testing in serotype-specific qPCRs the DNA extracted from all bacterial growth harvested from culture-plates. Next, we quantified with qPCR serotypes in uncultured samples and compared serotype ranks before and after culture-enrichment.
Results
Co-presence of multiple serotypes has been detected in 37 (5.6%) of 658 nasopharyngeal samples. The number of serotype carriage events detected by any method in these 37 samples was 83 (2-5 per sample) while the number of strains cultured was 42 (1-2 per sample). For the majority of samples (n=27 or 73%) the serotype ranks in uncultured and culture-enriched samples matched. A shift in serotype rank was observed in 11% of the samples (4 of 37) whereas in another 16% (6 of 37) the discordance was due to fewer serotypes detected in uncultured samples.
Conclusions
While increasing sensitivity of carriage detection, culture-enrichment has limited impact on the rank of serotypes present in nasopharyngeal swabs and can therefore be used to provide insight into co-carriage dynamics.
IMPACT AND EFFECTIVENESS OF THE 10-VALENT PNEUMOCOCCAL CONJUGATE VACCINE ON INVASIVE PNEUMOCOCCAL DISEASE IN THE NETHERLANDS (ID 443)
Abstract
Background
In 2011, 10-valent pneumococcal conjugate vaccination (PCV10) was introduced in the Dutch National Immunization Program, after five years of PCV7. We report on the impact and effectiveness of PCV10 in the Netherlands.
Methods
We included IPD cases reported from June 2004 up to May 2019 to our surveillance system. We estimated vaccine effectiveness using the indirect cohort method in children eligible for PCV10. We assessed impact in four age groups by comparing IPD incidences in June 2017-May 2019 and June 2009-May 2011 (before switch to PCV10).
Results
Effectiveness of at least two doses of PCV10 was 90% (63%;97%) against PCV10-type IPD and 29% (-177%;82%) against 19A IPD. Overall IPD incidence decreased by 17% (-5%;35%) in children <5 years, 26% (9%;40%) in 5-49 year-olds, 6% (-10%;19%) in 50-64 year-olds and 2% (-9%;11%) in 65+ year-olds. 19A IPD incidence decreased by 17% (-41%;51%) in children <5 years and by 4% (-103%;55%) in 5-49 year-olds, and increased by 77% (12%;180%) in 50-64 year-olds and by 35% (-1%;84%) in 65+ year-olds.
Conclusions
Despite good effectiveness on vaccine serotypes, the switch to PCV10 has had limited impact on further reducing overall IPD burden after five years of PCV7. Serotype 19A IPD incidence is slowly increasing in older adults.
DYNAMICS OF BACTERIAL CARRIAGE DURING 12 YEARS POST PNEUMOCOCCAL CONJUGATE VACCINE (PCV) INTRODUCTION IN THE NETHERLANDS (ID 871)
Abstract
Background
Control of pneumococcal carriage is key to prevention of pneumococcal disease. We assessed the impact of PCV on carriage prevalence of Streptococcus pneumoniae(Sp) serotypes but also of Haemophilus influenzae(Hi), Staphylococcus aureus(Sa), Moraxella catarrhalis(Mc) and Group A Streptococcus(GAS).
Methods
Cross sectional observational study on carriage prevalence, determined by culture of nasopharyngeal swabs, in 24-month-old children performed in 2018/2019. Data were compared to studies performed in 2009, 2010, 2012 and 2015.
Results
Since PCV7 introduction in 2006 and change to PHiD-CV10 in 2011, overall carriage prevalence has decreased for Sp (66 to 49%) but increased for Hi (52 to 73%), Mc (59 to 83%), Sa (5.6 to 10%) and GAS (2.2 to 6.1%). Pneumococcal PHiD-CV10-type serotypes have disappeared. Initially carriage rate of NVT serotypes 19A, 11A, 10A and 23A increased but has declined again; 6C, 15A, 15B and 23B prevalence is still increasing. In 2018, 6C, 19A, 23B and 15B were the predominant serotypes in carriage and invasive disease in children <5 years of age.
Conclusions
Twelve years post-PCV introduction the decline in pneumococcal carriage has stabilized, but changes in frequency and nature of carried NVT Sp, Hi, Sa, Mc and GAS continued and should be considered for invasive and respiratory infection predictions.
DYNAMICS OF PNEUMOCOCCAL CARRIAGE ASSOCIATED WITH INFLUENZA-LIKE ILLNESS IN COMMUNITY-DWELLING OLDER ADULTS (ID 975)
Abstract
Background
In older adults, pneumococcal disease is strongly associated with viral respiratory infections, though the impact of viruses on pneumococcal carriage remains poorly understood. Here, we have investigated effects of influenza-like illness (ILI) on pneumococcal carriage in older adults.
Methods
Pneumococcal presence was determined in saliva samples that were collected in the 2014/2015 influenza season from individuals aged ≥60 years, including 232 individuals with ILI sampled trice and 194 controls sampled twice. Pneumococcal carriage was detected with quantitative-PCRs targeting piaB and lytA genes in minimally-processed saliva and culture-enriched saliva. Bacterial and pneumococcal abundances were determined in minimally-processed saliva. Respiratory viruses were detected in nasopharyngeal and oropharyngeal samples using qPCR.
Results
In general, pneumococcal carriage was significantly associated with exposure to young children and rhinovirus infection. The prevalence of pneumococcal carriage was highest at ILI-onset (18%) and lowest among controls (11-13%). Compared with controls, both absolute and relative pneumococcal abundances were significantly elevated at ILI-onset and remained elevated 7-9 weeks later. Pneumococcal abundances were highest in individuals with carriage acquisition between ILI-onset and 2-3 weeks later.
Conclusions
Our findings support the notion that in older adults acute respiratory infections favor pneumococcal colonization of the upper respiratory tract and this impact persists beyond recovery from ILI.
ANTIBIOTIC RESISTANCE PREDICTION WITH WHOLE GENOME SEQUENCING OF STREPTOCOCCUS PNEUMONIAE CARRIAGE ISOLATES COLLECTED BETWEEN 2009-2018 IN THE NETHERLANDS (ID 566)
Abstract
Background
We investigated the use of whole genome sequencing (WGS) to predict antibiotic resistance of circulating S. pneumoniae (pneumococcus) carriage isolates collected among PCV7 and PCV10-vaccinated toddlers in the Netherlands.
Methods
All Pneumococcal strains (n=737) isolated between 2009-2018 from 24-months old carriers were subjected to WGS. Genome assembly of short reads into contigs was performed using SPAdes, which were subsequently assigned a taxonomic origin with Kraken2. All DNA sequences identified as pneumococcus were used for resistance gene identification with RGI. Predicted resistance genes with ≥50 bitscore and ≥80% sequence identity were further analyzed and compared against phenotypical antibiotic resistance data. Susceptibility testing was performed according to EUCAST guidelines.
Results
Based on WGS data 9.8% (72/737) of pneumococcal isolates were predicted to harbor resistance genes. Genetic markers of antibiotic resistance predicted by WGS were in concordance with resistotypes determined using the EUCAST-recommended method. Lack of susceptibility to penicillins was primarily observed for serotypes 19A (13% of 128) and 23B (19% of 63), respectively.
Conclusions
We have observed good congruence between antibiotic resistance prediction with WGS and standard phenotypical antibiotic sensitivity testing. Antibiotic resistance among pneumococcal carriage isolates in the Netherlands is relatively rare and is characterized by circulation of resistant serotype 19A and 23B strains.