Sopio Chochua, United States of America

Author Of 3 Presentations

 Conference Calendar

PREVALENCE OF VACCINE-TYPE PNEUMOCOCCAL CARRIAGE FIVE YEARS AFTER 13-VALENT PNEUMOCOCCAL CONJUGATE VACCINE (PCV13) INTRODUCTION IN GHANA (ID 663)

Session Name
Vaccines - Impact of Vaccine programs and Serotype Replacement
Presenter
Authors

Abstract

Background

Outbreaks of vaccine-type (VT) pneumococcal meningitis, especially serotype 1 (ST1), continue in Ghana despite PCV13 introduction in 2012 (6, 10, and 14-week schedule) and coverage >85%. We assessed VT-pneumococcal carriage prevalence, focusing on ST1, during the 2018 meningitis season

Methods

We conducted a cross-sectional nasopharyngeal (NP) carriage survey from February-July in three northern Ghana “meningitis belt” regions. Individuals aged 6 weeks-35 years with respiratory symptoms or clinical signs of meningitis were recruited from emergency departments across 6 hospitals. Pneumococci isolated from NP swabs were serotyped by Quellung; ST1 isolates were sequenced.

Results

Among 934 participants, 671 (71.8%) carried pneumococci. Overall and VT-pneumococcal carriage were 76.3% (464/608) and 21.5% (131/608) in <5 years, 67.4% (116/172) and 26.7% (46/172) in 5-14 years, and 59.1% (91/154) and 19.5% (30/154) in 15-35 years, respectively. ST1 colonization was lower in participants <5 versus ≥ 5 years-old (0.3% [2/608] vs. 3.1% [10/326]; P=0.001). All ST1 isolates were sequence type 217/303, but not closely related. Serotypes 3, 19F, 23F, 6A and 14 were the most prevalent PCV13-types.

Conclusions

VT-pneumococcal carriage remains common in Ghana, with ST1 colonization more common among those too old to have received PCV13. Vaccination strategies to decrease VT-pneumococcal transmission are needed.

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BACTERIAL MUTATIONS ASSOCIATED WITH MENINGITIS AMONG INVASIVE PNEUMOCOCCAL DISEASE (IPD) PATIENTS (ID 826)

Session Name
Basic Sciences - Genomics and Transmission
Presenter
Authors

Abstract

Background

Our understanding on bacterial genetic determinants of pneumococcal disease manifestation is still limited. We aim to confirm the previous findings and identify additional bacterial variants associated with meningitis.

Methods

We sequenced IPD isolates identified through the Active Bacterial Core surveillance (ABCs) in the United States from 2016 to 2017. We evaluated the association between meningitis and a previously reported pneumococcal pbp1b641C allele by using a mixed-effects logistic regression model accounting for population structure (represented by multi-locus sequence type) and potential confounders (pneumococcal serotype, antibiotic resistance, and patient age). We also performed a k-mer based bacterial genome-wide association study (GWAS).

Results

Among all 5560 sequenced IPD isolates, 371 (6.7%) were from meningitis cases. Among the 576 isolates carrying the pbp1b641C allele, 86 (14.9%) were meningitis. After adjusting for covariates, the pbp1b641C allele was significantly associated with meningitis (OR=1.76, 95% CI,1.10-2.81). Pneumococcal genome contents explained 8.2% (95% CI,1.6%-13.2%) of variation in meningitis in the GWAS. Additional pneumococcal mutations that showed significant association were identified in loci including SP_1448 (conserved hypothetical protein, p=1.7×10-8), SP_2167 (L-fuculokinase, p=3.6×10-8), and SP_0647 (phosphotransferase, p=1.0×10-7).

Conclusions

IPD manifestation varied significantly according to pneumococcal genomes. More knowledge on such mutations could help better understand bacterial pathogenesis and clinical outcome.

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GENOMIC CLUSTERS OF INVASIVE PNEUMOCOCCAL DISEASE (IPD) ISOLATES, USA, 2015-2017 (ID 833)

Session Name
Population Sciences - Epidemics, Outbreaks and Special Settings
Presenter
Authors

Abstract

Background

Outbreaks of pneumococcal infections have been reported in closed settings and are often caused by clusters of genomically highly related isolates (genomic clusters), suggesting close transmission connections.

Methods

We used whole-genome sequencing (WGS) to characterize all IPD isolates identified through the Active Bacterial Core surveillance (ABCs) from 2015 to 2017. We identified genomic clusters by performing hierarchical cluster analysis of pair-wise genomic distances and applying a cut-off value of 3-base difference per 1.8Mb shared genome.

Results

WGS characterized 8029 isolates representing 87% of all IPD cases. The cluster analysis identified 379 genomic clusters accounting for 847 (11%) of the isolates. Higher proportions of clustered isolates (isolates belonging to any clusters) were found in serotypes 12F (36%), 4 (26%), and 7F (25%), while lower proportions were found in serotypes 35F, 7C, 15A, 23B (each <1.5%), and penicillin non-susceptible isolates (4%). Clustered isolates were significantly associated with patients who were homeless (OR=3.3), who were injecting drugs (OR=2.1), and who were 25 to 50 years of age (OR=1.5; all p-values < 0.001).

Conclusions

IPD genomic clusters were associated with specific patient and strain features in the ABCs population. Understanding the dynamics and demographics of vaccine-serotype clusters could help identify new target groups to inform vaccine policy.

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