Abstract
For epidemiological and surveillance purposes, it is relevant to monitor the distribution and dynamics of Streptococcus pneumoniae serotypes. Conventional serotyping methods do not provide rapid or quantitative information on serotype loads. Quantitative serotyping may enable prediction of the invasiveness of a specific serotype compared to other serotypes carried. Here, we describe a novel, rapid multiplex real-time PCR assay for identification and quantification of the 40 most prevalent pneumococcal serotypes and the assay impacts in pneumonia specimens from emerging and developing countries. Eleven multiplex PCR to detect 40 serotypes or serogroups were optimized. Quantification was enabled by reference to standard dilutions of known bacterial load. Performance of the assay was evaluated to specifically type and quantify S. pneumoniae in nasopharyngeal and blood samples from adult and pediatric patients hospitalized with pneumonia (n = 664) from five different countries. Serogroup 6 was widely represented in nasopharyngeal specimens from all five cohorts. The most frequent serotypes in the French, South African, and Brazilian cohorts were 1 and 7A/F, 3 and 19F, and 14, respectively. When both samples were available, the serotype in blood was always present as carriage with other serotypes in the nasopharynx. Moreover, the ability of a serotype to invade the bloodstream may be linked to its nasopharyngeal load. The mean nasopharyngeal concentration of the serotypes that moved to the blood was 3 log-fold higher than the ones only found in the nasopharynx. This novel, rapid, quantitative assay may potentially predict some of the S. pneumoniae serotypes invasiveness and assessment of pneumococcal serotype distribution.
Highlights
Streptococcus pneumoniae is the major pathogen implicated in community-acquired pneumonia (CAP) in adults and children
In order to determine the complex relationship between capsule composition, serotype-specific load, the risk of infection for healthy carriers and disease severity, we developed a real-time multiplex PCR method to accurately serotype and quantify the bacterial concentration of 40 globally-prevalent S. pneumoniae serotypes
Twenty nine isolated strains representatives of 29 different Streptococcus species provided by bioMérieux, France, were used: S. agalactiae, S. anginosus, S. australis, S. bovis, S. canis, S. constellatus ssp constellatus, S. constellatus ssp pharynges, S. cristatus, S. downei, S. ferus, S. gordonii, S. infantarius ssp coli, S. infantarius ssp infantarius, S. infantis, S. iniae, S. intermedius, S. mitis, S. oralis, S. mutans, S. oligofermentans, S. parasanguinis, S. peroris, S. pseudopneumoniae, S. pyogenes, S. ratti, S. salivarius ssp salivarius, S. sanguinis, S. sinensis, S. sobrinus
Summary
Streptococcus pneumoniae is the major pathogen implicated in community-acquired pneumonia (CAP) in adults and children. CAP is a major public health problem worldwide; more than one million people die of pneumococcal disease every year including ~800,000 deaths in children aged under five [1], mostly in developing countries [2,3]. About 10 different S. pneumoniae serotypes have been described to account for the majority of invasive pneumococcal disease worldwide [6]. Prior to the introduction of pneumococcal vaccines, a limited number of serotypes and serogroups were frequently associated with pediatric disease (serotypes 4 and 14 and serogroups 6, 7, 9, 18, 19, and 23) [7]. The distribution of serotypes can vary with age, geography and time [8], which increases the challenges for vaccine development
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
