Pneumococcus nasopharyngeal carriage in children attending an academic hospital in Pretoria, South Africa, after the introduction of pneumococcal vaccine.

Charity Newton,Siyazi Mda,Caroline Maluleka,Harry Maake

doi:10.4102/sajid.v34i1.112

Abstract

BackgroundIn 2009, pneumococcal conjugate vaccine was introduced in South Africa. However, there are concerns that this could lead to an increase in colonisation of non-vaccine serotypes (serotype replacement).MethodsIn a cross-sectional study, 350 children aged 1 month to 14 years were enrolled at Dr George Mukhari Academic Hospital from December 2015 to April 2016. We assessed the prevalence of nasopharyngeal colonisation with pneumococcus and characterised the serotypes found.ResultsThe median age of the cohort was 33.7 months (interquartile range 16.27–69.5 months), with 20% being < 1 year. A total of 21% of the children were diagnosed with pneumococcal-related conditions; among these, pneumonia was the most common condition. Less than half (43%) of the participants were fully immunised. Forty-six (13%) of the children were colonised with pneumococcus. Younger age was significantly associated with pneumococcal colonisation. Among those colonised with pneumococcus, 35% were fully immunised, 30% were partially immunised, 30% had an unknown immunisation status and 4% were unimmunised. Eight (17%) of the children who were colonised with pneumococcus had pneumococcal-related conditions. The commonest serotype identified was 6A/B. Overall, 2% of the cohort were colonised with vaccine-serotype pneumococcus.ConclusionAs a minority of children had evidence of nasopharyngeal colonisation with vaccine-serotype pneumococci, serotype replacement may be emerging in our population.

Highlights

It is estimated that pneumococcal disease accounts for about 300 000 deaths in children, and half of these occur in Africa.[1]
Nasopharyngeal pneumococcal colonisation is common in children[5] and it is a prerequisite for developing pneumococcal disease.[2,4,6]
Vaccine serotype colonisation was found to be 2% in our study, which is lower than the 22% found in a South African study conducted 2 years after the pneumococcal conjugate vaccine (PCV) roll-out;[7] this is likely an effect of immunisation

Summary

Introduction

It is estimated that pneumococcal disease accounts for about 300 000 deaths in children, and half of these occur in Africa.[1] The incidence of pneumococcal disease differs in many populations and factors such as overcrowding, poverty, human immunodeficiency virus (HIV) and genetics have been attributed as contributing to these differences.[2]. Streptococcus pneumoniae (pneumococcus) is part of the commensal flora of the respiratory tract.[3,4] Nasopharyngeal pneumococcal colonisation is common in children[5] and it is a prerequisite for developing pneumococcal disease.[2,4,6] Colonisation is the main source for transmission of the bacterium within communities; preventing nasopharyngeal colonisation in children is a strategy for preventing disease in children and adults.[4] Immunisation of children with pneumococcal conjugate vaccine (PCV) has been shown to decrease the risk of acquiring vaccine serotype nasopharyngeal colonisation.[7]. There are concerns that this could lead to an increase in colonisation of non-vaccine serotypes (serotype replacement)

Methods

Results

Conclusion