Alienke Wijmenga-Monsuur, Netherlands
National Institute for Public Health and the Environment Center for Infectious Disease Control NetherlandsAuthor Of 3 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.
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.
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.