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

Abstract

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.

Impact of pneumococcal conjugate vaccine on the carriage density of Streptococcus pneumoniae and Staphylococcus aureus in children living with HIV: a nested case–control study

“…19 Quantitative PCR is gaining recognition to study carriage and the impact of PCVs, particularly on the dynamics of serotypespecific carriage density. 32,33 The pneumococcal carriage density determines disease severity in HIV-infected adults 3 and is associated with transmission. 2,4 Through qPCR, we could quantify the density of carriage and the detection limit increased.…”

“…35 Increased carriage density in the context of HIV could be due to a decrease in pneumococcus specific CD4-T lymphocytes, particularly the CD154 response, which is known to clear pneumococcus. 32,36 The impact of PCVs on the density of VT versus NVT serotypes is less clear. 32,34,[37][38][39] We found an overall drop in pneumococcal density post-PCV13.…”

“…32,36 The impact of PCVs on the density of VT versus NVT serotypes is less clear. 32,34,[37][38][39] We found an overall drop in pneumococcal density post-PCV13. This warrants further investigation in high-risk families.…”

Performance of the Biomark HD real-time qPCR System (Fluidigm) for the detection of nasopharyngeal bacterial pathogens and Streptococcus pneumoniae typing

“…catarrhalis , S pyogenes , and N meningitides by qPCR 11 , and pneumococcal serotyping was done by qPCR on all samples that tested positive for S . pneumoniae as described 30 . In this study, we now developed and evaluated a Fluidigm assay which screened for an additional 9 serotypes/serogroups (7A/F, 8, 22A/F, 25AF/38 and 35B) not included in our earlier qPCR assay, as well as investigated for presence of additional bacteria ( Bordetella bronchiseptica , Bordetella parapertusis , Bordetella pertussis , Bordetella holmesii, and Neisseria lactamica .…”