Thandie S. Mwalukomo,
Poster Author Of 1 e-Poster
PNEUMOCOCCAL SEROTYPES IN INFANTS LESS THAN 90 DAYS OLD BEFORE AND AFTER INTRODUCTION OF PNEUMOCOCCAL CONJUGATE VACCINE (PCV) IN BLANTYRE, MALAWI
Author Of 3 Presentations
PNEUMOCOCCAL SEROTYPES IN INFANTS LESS THAN 90 DAYS OLD BEFORE AND AFTER INTRODUCTION OF PNEUMOCOCCAL CONJUGATE VACCINE (PCV) IN BLANTYRE, MALAWI (ID 1071)
Abstract
Background
Malawi introduced PCV13 into its Expanded Program on Immunization in November 2011. Our aim was to describe the change in serotype distribution causing invasive pneumococcal disease (IPD) in neonates and young infants in Blantyre, Malawi.
Methods
We conducted a retrospective study of IPD in infants aged <90 days admitted to Queen Elizabeth Central Hospital (QECH) in Blantyre, Malawi between 2005 and 2018. IPD was defined as culture-confirmed Streptococcus pneumoniae from blood or cerebrospinal fluid, collected when clinically indicated. Serotype was determined by Latex agglutination.
Results
We identified and serotyped samples of 130 cases of IPD. Results show that overall, serotypes 5 (19%), 1 (11%), 7F (5%), 6A/B (3%), and 23F (3%) were most common in this population over the time period studied. Non-vaccine serotype (NVT) accounted for 19% of cases and 40 samples were not typeable. Serotypes 5 and 1 were the predominant cause of IPD before as well as after PCV13 introduction.
Conclusions
Overall IPD cases have been on the decline in this population. Vaccine-type serotypes were the main cause of IPD in neonates and young infants, both before and after PCV13 introduction. Vaccine strategies should be considered to optimise the potential for reducing VT-IPD in this setting among this vulnerable population.
RAPID WANING OF VACCINE-INDUCED IMMUNITY AMONG PCV13-VACCINATED CHILDREN UNDER 5 YEARS OLD IN MALAWI WITH SUBSEQUENT ACQUISITION OF NATURAL ANTIBODY THROUGH NATURAL EXPOSURE (ID 267)
INCREASE IN FREQUENCY OF PNEUMOCOCCAL METABOLIC GENOTYPES CHARACTERISED BY ANTIMICROBIAL RESISTANCE AND ADAPTATIONS FOR COLONIZATION AFTER PCV13 INTRODUCTION IN BLANTYRE, MALAWI. (ID 416)
- Andrea Gori, United Kingdom
- Uri Obolski, Israel
- Todd D. Swarthout, Malawi
- Jose Lourenço, United Kingdom
- Caroline M. Weight, United Kingdom
- Jen Cornick,
- Dean Everett, Malawi
- Arox Kamng'ona,
- Thandie S. Mwalukomo,
- Martin C. Maiden, United Kingdom
- Neil French, United Kingdom
- Sunetra Gupta, United Kingdom
- Robert S. Heyderman, United Kingdom
Abstract
Background
Streptococcus pneumoniae naturally undergoes fluctuations in genotype. We previously showed a high residual prevalence of vaccine serotype (VT) pneumococci (18% in under 5’s) 7 years after PCV13 introduction in Malawi. In this context, we hypothesised the emergence and fixation of S. pneumoniae lineages with genetic traits conveying a competitive advantage in the nasopharyngeal niche.
Methods
1826 S. pneumoniae genomes were analysed from isolates collected during rolling cross-sectional carriage surveys in Blantyre, 4-7 years after PCV13 introduction. The metabolic core-genome includes 175 discrete metabolic genotypic profiles (metabolic types, MTs). Relative fitness was assessed by in-vitro growth and adhesive potential evaluated using Detroit 562 nasopharyngeal epithelial cells.
Results
High residual pneumococcal carriage is characterised by persistent MTs in VT (e.g. 3 and 23F) and emerging new MTs in non-VT (NVT; 38 and 23B). Increase in AMR MTs among 38 and 23B was observed. Emerging MTs show characteristic sequences of virulence genes and are characterised phenotypically by higher growth potential and propensity for better adherence to NP cell. We identified convergent evolution between MTs isolated in different countries, result of genetic bottlenecks.
Conclusions
This shift in metabolic genotypes, antimicrobial resistance and colonization adaptations may facilitate vaccine escape.