Molecular surveillance of pneumococcal carriage following completion of immunization with the 13-valent pneumococcal conjugate vaccine administered in a 3 + 1 schedule

Abstract

In a cross-sectional study, with the use of molecular methods, we aimed to gain insight into oropharyngeal pneumococcal colonization over time in 1212 Greek children recruited in general pediatric settings throughout the country; they were fully vaccinated with PCV13 (3 + 1 schedule). A single sample was obtained from each child at a time interval of 26 days to 70 months after administration of the 4th (booster) PCV13 dose; sampling time was divided into six time intervals. Carriage of Streptococcus pneumoniae was detected by real-time PCR targeting the lytA gene and isolates were serotyped by singleplex real-time PCR assays. Multiple control procedures to avoid false-positive results were applied. We showed an overall S. pneumoniae carriage rate of 48.6%. Serotyping identified typeable isolates in 82% of the total lytA-positive samples. Non-PCV13 serotypes represented 83.8% of total isolates when excluding serogroups with mixed PCV13 and non-PCV13 serotypes. In multivariate analysis daycare/school attendance emerged as the main contributing factor. Notably, serotypes 19A and 3 were the only two PCV13 serotypes the colonization rate of which increased over time (χ2 for trend P < 0.001 and P = 0.012, respectively). The application of the SP2020 gene on lytA-positive serotyped samples showed pneumococcal colonization in 97% of cases, and the overall colonization profile over time closely resembled that of the lytA gene. With the provisions of the methodological approach and age group of our study, the use of the oropharynx emerges as a reliable alternative to the nasopharynx in estimating pneumococcal carriage in epidemiological studies.

High Levels of Detection of Nonpneumococcal Species of Streptococcus in Saliva from Adults in the United States

“…However, the processing and analyzing of samples collected in carriage studies is an extensive process. As such, the data presented in the current study is within a time frame (sample collection to reporting) similar to the reports from surveillance on pneumococcal carriage conducted by others ( 4 , 33 , 34 ). Still, we feel that the data presented in this study remains relevant to the field as the issue of confounding of PCR assays used for the detection of pneumococcus was first reported much prior to this and still holds true today.…”

Pneumococcal carriage and serotype distribution in children with nephrotic syndrome

“…The samples that tested positive for S. pneumoniae were subjected to Sanger sequencing and examined using the methodology described by Marmaras et al [11]. The sequences were subsequently uploaded to the S. pneumoniae CST Typing Tool to determine the serotype of S. pneumoniae [12].…”

Estimating the Clinical and Economic Impact of Switching from the 13-Valent Pneumococcal Conjugate Vaccine (PCV13) to Higher-Valent Options in Greek Infants

“…Of the 18 fatal meningitis cases reported in the study, a large proportion of fatalities were caused by the additional serotypes included in higher-valent PCVs, with serotypes 10A, 8, and 22F contributing to 22% of all fatalities [ 15 ]. Finally, in a cross-sectional study from 2017 on pneumococcal carriage in children fully vaccinated with PCV13 in Greece, NVTs represented 83.8% of total isolates when excluding serogroups with mixed PCV13 and non-PCV13 serotypes [ 16 ]. Serotypes/serogroups 15A/B/C/F and 11A/D/E were the most prevalent serotypes/serogroups in pneumococcal carriage (13.8% and 11.4%, respectively).…”