Use of Multiplex Quantitative PCR To Evaluate the Impact of Pneumococcal Conjugate Vaccine on Nasopharyngeal Pneumococcal Colonization in African Children

ABSTRACT Pneumococcal conjugate vaccine (PCV) immunization of children induces shifts in colonizing pneumococcal serotypes. This study evaluated the effect of infant vaccination with 7-valent PCV (PCV7) on vaccine serotype (VT) colonization and whether the increase in nonvaccine serotype (NVT) was d...

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Autores principales:	Courtney P. Olwagen, Peter V. Adrian, Marta C. Nunes, Michelle J. Groome, Mark F. Cotton, Avy Violari, Shabir A. Madhi
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2017
Materias:	PCV7 vaccination serotype replacement unmasking Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/6c4cd540ecb643678b151a62940a3141
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spelling	oai:doaj.org-article:6c4cd540ecb643678b151a62940a31412021-11-15T15:21:51ZUse of Multiplex Quantitative PCR To Evaluate the Impact of Pneumococcal Conjugate Vaccine on Nasopharyngeal Pneumococcal Colonization in African Children10.1128/mSphere.00404-172379-5042https://doaj.org/article/6c4cd540ecb643678b151a62940a31412017-12-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mSphere.00404-17https://doaj.org/toc/2379-5042ABSTRACT Pneumococcal conjugate vaccine (PCV) immunization of children induces shifts in colonizing pneumococcal serotypes. This study evaluated the effect of infant vaccination with 7-valent PCV (PCV7) on vaccine serotype (VT) colonization and whether the increase in nonvaccine serotype (NVT) was due to either unmasking of previously low-density-colonizing serotypes or increase in acquisition of NVT. A multiplex quantitative PCR (qPCR) was used to evaluate VT and NVT nasopharyngeal colonization in archived swabs of PCV-vaccinated and PCV-unvaccinated African children at 9 and 15 to 16 months of age. Molecular qPCR clearly identified the vaccine effect typified by a decrease in VT colonization and an increase in NVT colonization. Serotype 19A was primarily responsible for the higher NVT carriage among PCV vaccinees at 9 months of age (53.4% difference; P = 0.021) and 16 months of age (70.7% difference; P < 0.001). Furthermore, the density of serotype 19A colonization was higher in PCV-vaccinated groups than in PCV-unvaccinated groups (3.76 versus 2.83 CFU/ml [P = 0.046], respectively, and 4.15 versus 3.04 CFU/ml [P = 0.013], respectively) at 9 and 16 months of age, respectively. Furthermore, serotype 19A was also more commonly reported as a primary isolate (by having the highest density among other cocolonizing serotypes identified in the sample) in PCV7-vaccinated children, while being equally a primary (46.2%) or nonprimary (53.8%) isolate in PCV-unvaccinated children. Molecular qPCR showed both serotype replacement and unmasking to be the cause for the increase in NVT colonization in PCV7-vaccinated children, as some serotypes were associated with an absolute increase in colonization (replacement), while others were associated with an increase in detection (unmasking). IMPORTANCE This study focused on evaluating the effect of infant vaccination with 7-valent pneumococcal conjugate vaccine (PCV7), using a multiplex qPCR method, on the density of serotype-specific nasopharyngeal colonization in order to delineate the relative role of serotype replacement versus unmasking as the cause for the increase in nonvaccine serotype colonization in PCV7-vaccinated children. This is pertinent in the context of the ongoing deployment of PCV immunization in children, with surveillance of colonization considered an early proxy for disease that might arise from nonvaccine serotypes, as well as the success of childhood vaccination on indirect effect in the community through the interruption of pneumococcal transmission from vaccinated young children.Courtney P. OlwagenPeter V. AdrianMarta C. NunesMichelle J. GroomeMark F. CottonAvy ViolariShabir A. MadhiAmerican Society for MicrobiologyarticlePCV7 vaccinationserotype replacementunmaskingMicrobiologyQR1-502ENmSphere, Vol 2, Iss 6 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	PCV7 vaccination serotype replacement unmasking Microbiology QR1-502
spellingShingle	PCV7 vaccination serotype replacement unmasking Microbiology QR1-502 Courtney P. Olwagen Peter V. Adrian Marta C. Nunes Michelle J. Groome Mark F. Cotton Avy Violari Shabir A. Madhi Use of Multiplex Quantitative PCR To Evaluate the Impact of Pneumococcal Conjugate Vaccine on Nasopharyngeal Pneumococcal Colonization in African Children
description	ABSTRACT Pneumococcal conjugate vaccine (PCV) immunization of children induces shifts in colonizing pneumococcal serotypes. This study evaluated the effect of infant vaccination with 7-valent PCV (PCV7) on vaccine serotype (VT) colonization and whether the increase in nonvaccine serotype (NVT) was due to either unmasking of previously low-density-colonizing serotypes or increase in acquisition of NVT. A multiplex quantitative PCR (qPCR) was used to evaluate VT and NVT nasopharyngeal colonization in archived swabs of PCV-vaccinated and PCV-unvaccinated African children at 9 and 15 to 16 months of age. Molecular qPCR clearly identified the vaccine effect typified by a decrease in VT colonization and an increase in NVT colonization. Serotype 19A was primarily responsible for the higher NVT carriage among PCV vaccinees at 9 months of age (53.4% difference; P = 0.021) and 16 months of age (70.7% difference; P < 0.001). Furthermore, the density of serotype 19A colonization was higher in PCV-vaccinated groups than in PCV-unvaccinated groups (3.76 versus 2.83 CFU/ml [P = 0.046], respectively, and 4.15 versus 3.04 CFU/ml [P = 0.013], respectively) at 9 and 16 months of age, respectively. Furthermore, serotype 19A was also more commonly reported as a primary isolate (by having the highest density among other cocolonizing serotypes identified in the sample) in PCV7-vaccinated children, while being equally a primary (46.2%) or nonprimary (53.8%) isolate in PCV-unvaccinated children. Molecular qPCR showed both serotype replacement and unmasking to be the cause for the increase in NVT colonization in PCV7-vaccinated children, as some serotypes were associated with an absolute increase in colonization (replacement), while others were associated with an increase in detection (unmasking). IMPORTANCE This study focused on evaluating the effect of infant vaccination with 7-valent pneumococcal conjugate vaccine (PCV7), using a multiplex qPCR method, on the density of serotype-specific nasopharyngeal colonization in order to delineate the relative role of serotype replacement versus unmasking as the cause for the increase in nonvaccine serotype colonization in PCV7-vaccinated children. This is pertinent in the context of the ongoing deployment of PCV immunization in children, with surveillance of colonization considered an early proxy for disease that might arise from nonvaccine serotypes, as well as the success of childhood vaccination on indirect effect in the community through the interruption of pneumococcal transmission from vaccinated young children.
format	article
author	Courtney P. Olwagen Peter V. Adrian Marta C. Nunes Michelle J. Groome Mark F. Cotton Avy Violari Shabir A. Madhi
author_facet	Courtney P. Olwagen Peter V. Adrian Marta C. Nunes Michelle J. Groome Mark F. Cotton Avy Violari Shabir A. Madhi
author_sort	Courtney P. Olwagen
title	Use of Multiplex Quantitative PCR To Evaluate the Impact of Pneumococcal Conjugate Vaccine on Nasopharyngeal Pneumococcal Colonization in African Children
title_short	Use of Multiplex Quantitative PCR To Evaluate the Impact of Pneumococcal Conjugate Vaccine on Nasopharyngeal Pneumococcal Colonization in African Children
title_full	Use of Multiplex Quantitative PCR To Evaluate the Impact of Pneumococcal Conjugate Vaccine on Nasopharyngeal Pneumococcal Colonization in African Children
title_fullStr	Use of Multiplex Quantitative PCR To Evaluate the Impact of Pneumococcal Conjugate Vaccine on Nasopharyngeal Pneumococcal Colonization in African Children
title_full_unstemmed	Use of Multiplex Quantitative PCR To Evaluate the Impact of Pneumococcal Conjugate Vaccine on Nasopharyngeal Pneumococcal Colonization in African Children
title_sort	use of multiplex quantitative pcr to evaluate the impact of pneumococcal conjugate vaccine on nasopharyngeal pneumococcal colonization in african children
publisher	American Society for Microbiology
publishDate	2017
url	https://doaj.org/article/6c4cd540ecb643678b151a62940a3141
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Use of Multiplex Quantitative PCR To Evaluate the Impact of Pneumococcal Conjugate Vaccine on Nasopharyngeal Pneumococcal Colonization in African Children

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