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Characterisation of Invasive Streptococcus pneumoniae Isolated from Cambodian Children between 2007 - 2012
Catrin E Moore1,2,3,4, Adam Giess3, Sona Soeng2
1Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
Insights
Invasive pneumococcal disease (IPD) significantly impacts Cambodian children, with high mortality. The 13-valent pneumococcal conjugate vaccine (PCV13) demonstrates high coverage for common serotypes, crucial for monitoring post-vaccination epidemiology.
Area of Science:
- Pediatrics
- Infectious Diseases
- Microbiology
Background:
- Invasive pneumococcal disease (IPD) poses a significant threat to child health in Cambodia.
- Limited data exist on prevalent pneumococcal serotypes causing IPD in Cambodia.
- Understanding circulating serotypes is vital for evaluating vaccine impact post-introduction of the 13-valent pneumococcal conjugate vaccine (PCV13).
Purpose of the Study:
- To characterize the common serotypes causing IPD in Cambodian children.
- To assess antimicrobial resistance patterns of Streptococcus pneumoniae isolates.
- To evaluate the potential coverage of existing pneumococcal vaccines.
Main Methods:
- Retrospective study of IPD cases in children at Angkor Hospital for Children (2007-2012).
- Phenotypic serotyping and whole genome sequencing of Streptococcus pneumoniae isolates.
- Analysis of antimicrobial susceptibility, serotype distribution, and vaccine coverage.
Main Results:
- Ninety children hospitalized with IPD; case fatality rate was 15.6%.
- Common serotypes included 1, 23F, 14, 5, and 19A. Significant antimicrobial resistance was observed.
- PCV13, PCV10, and PCV7 coverage was 92%, 76%, and 44%, respectively. Novel sequence types and resistotypes were identified.
Conclusions:
- IPD is a critical pediatric illness in Cambodia with substantial mortality.
- PCV13 offers high coverage for the predominant serotypes identified in this study.
- Whole genome sequencing provided valuable insights into serotype and resistance profiles, identifying novel strains.
Background:
The 13-valent pneumococcal vaccine (PCV13) was introduced in Cambodia in January 2015. There are limited data concerning the common serotypes causing invasive pneumococcal disease (IPD). Knowledge of the circulating pneumococcal serotypes is important to monitor epidemiological changes before and after vaccine implementation.
Methods:
All episodes of IPD defined by the isolation of Streptococcus pneumoniae from blood, cerebrospinal fluid or other sterile site in Cambodian children admitted to the Angkor Hospital for Children in Siem Reap, Northwestern Cambodia, between 1st January 2007 and 1st July 2012 were retrospectively studied. Streptococcus pneumoniae isolates that could be retrieved underwent phenotypic typing and whole genome sequencing.
Results:
There were 90 Cambodian children hospitalized with IPD with a median (IQR) age of 2.3 years (0.9-6.2). The case fatality was 15.6% (95% CI 8-23). Of 50 Streptococcus pneumoniae isolates available for further testing, 46% were penicillin non-susceptible and 8% were ceftriaxone non-susceptible, 78% were cotrimoxazole resistant, 30% were erythromycin resistant and 30% chloramphenicol resistant. There were no significant changes in resistance levels over the five-year period. The most common serotypes were 1 (11/50; 22%), 23F (8/50; 16%), 14 (6/50; 12%), 5 (5/50; 10%) and 19A (3/50; 6%). Coverage by PCV7, PCV10 and PCV13 was 44%, 76% and 92% respectively. We identified novel multilocus sequence types and resistotypes using whole genome sequencing.
Conclusions:
This study suggests IPD is an important disease in Cambodian children and can have a significant mortality. PCV13 coverage of the serotypes determined in studied strains was high and consistent with another recent study. The phenotypic resistance patterns observed were similar to other regional studies. The use of whole genome sequencing in the present study provides additional typing and resistance information together with the description of novel sequence types and resistotypes.
