Results of a study published in Vaccine found that there was a low prevalence of Streptococcus pneumoniae nasopharynx-oropharynx colonization (NOC) in adults, but the prevalence was higher among younger adults. According to the study authors, NOC is a proposed new target to reduce the development of invasive pneumococcal disease in adults but there is limited information on NOC rates in this population.1
According to a separate study published in Open Forum Infectious Diseases, the rates of all-cause pneumonia per 100,000 patient-years were 953 for those aged 18 to 49 years, 2679 for those aged50 to 64 years, and 6930 for those ages 65 or older.2
Investigators of the current review aimed to synthesize and analyze existing data on the prevalence of S. pneumoniae NOC in adults. Data included were original observational studies such as cross-sectional, case-control, and cohort designs. The studies also had to include adults aged 18 years and older without symptoms or suspicion of viral or pneumococcal disease and the primary outcome had to be the identification of pneumococcal colonization, according to the study authors. Investigators included studies from PubMed, Science Direct, Web of Science, and Scopus, spanning from January 1, 1983, to May 31, 2023.1
A total of 319 potential articles were initially selected for review, with 175 excluded due to irrelevance and 75 failing to meet the inclusion criteria, according to the study authors. Investigators included 37 articles in the final meta-analysis, accounting for 23,724 individuals aged 18 and older. In 87% of the studies, pneumococcus was identified with traditional culture methods and 8% used PCR tests, while 5% combined both approaches. Further, 65% used nasopharyngeal swabs, 19% used a combination of nasopharyngeal swabs and oropharyngeal swabs, and 8% combined nasopharyngeal swabs with other sample types, according to the study authors.1
Investigators found that the overall prevalence of S. pneumoniae NOC among adults was 6%, while the subgroup analysis revealed that adults aged 18 to 64 years old had a prevalence of 10% and those 65 years and older had a prevalence of 2%. The high heterogeneity was >90% but fell to 70% when the analysis was restricted to just oropharyngeal swabs, showing that the identification of S. pneumoniae NOC could vary depending on the method used for diagnosis, according to the study authors.1
Key Takeaways
- A study published in Vaccine found that Streptococcus pneumoniae colonization in adults' throats (nasopharynx-oropharynx colonization or NOC) is uncommon, with an overall prevalence of only 6%.
- Younger adults (aged 18-64) were four times more likely to have this colonization compared to older adults (65+).
- This review highlights limitations in the existing research, including data overlap, missing information on specific bacterial strains and risk factors for colonization, and a lack of data from low- and middle-income countries.
Further, investigators found that the prevalence proportion of adults during the pre-pneumococcal conjugate vaccine (PCV) ranged from 21% to 18%, but the prevalence in the post-PCV period had a 0% to 26% range, according to the study authors.1
The study authors indicated that due to the overlap of data within different age groups, they excluded the data to avoid bias, which resulted in some data in the colonization proportion being derived from “less-than-ideal tables and images,” possibly introducing bias. Further, they noted there was a lack of data on serotypes, antibiotic sensitivity, risk factors, and vaccine dosage. Lastly, they said some results had poor information associated with low- and middle-income countries.1
Reference
Lozada J, Gómez JO, Serrano-Mayorga CC, et al. Streptococcus pneumoniae as a colonizing agent of the Nasopharynx - Oropharynx in adults: A systematic review and meta-analysis. Vaccine. 2024. doi:10.1016/j.vaccine.2024.03.041
Grant LR, Meche A, McGrath L, et al. Risk of Pneumococcal Disease in US Adults by Age and Risk Profile. Open Forum Infect Dis. 2023;10(5):ofad192. doi:10.1093/ofid/ofad192
