Characterisation of Invasive Streptococcus pneumoniae Isolated from Cambodian Children between 2007 - 2012.

Catrin E Moore,Nicole Stoesser,Varun Kumar,Pheakdey Nhoung,Adam Giess,Poda Sar,Nicholas P J Day,Christopher M Parry,Paul Turner,Rachel Bousfield,Sona Soeng,Paulo Lee Ho

doi:10.1371/journal.pone.0159358

Abstract

BackgroundThe 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.MethodsAll 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.ResultsThere 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.ConclusionsThis 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.

Highlights

Streptococcus pneumoniae causes an estimated one million childhood deaths each year, mostly in developing countries [1]
All episodes of invasive pneumococcal disease (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
This study suggests IPD is an important disease in Cambodian children and can have a significant mortality

Summary

Introduction

Streptococcus pneumoniae (pneumococcus, S. pneumoniae) causes an estimated one million childhood deaths each year, mostly in developing countries [1]. Strains carried in the upper airways are considered the reservoir of isolates that may cause lower respiratory tract infections, pneumonia and invasive disease. The serotypes causing disease in Asia have been recently reviewed but data is limited for Cambodia [3,4,5,6]. In a recent study of S. pneumoniae, 88% of 43 invasive isolates serotypes causing invasive pediatric disease in Cambodia in 2013–14 had a serotype covered by the PCV13 vaccine [7]. 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

Results

Conclusion