Non-Typeable Streptococcus pneumoniae and Pneumococcal Diseases: A Systematic Review and Meta-Analysis

Non-typeable Streptococcus pneumoniae strains are not covered in the current pneumococcal conjugate vaccines (PCVs). As a result, their increasing prevalence in pneumococcal diseases following the introduction of PCVs poses a significant public health concern. This study provides a global summary of the epidemiology of non-typeable pneumococcal diseases by estimating their prevalence and antimicrobial resistance rates, and identifying the circulating sequence types. An extensive search was conducted in PubMed, Scopus and Web of Science for studies reporting pneumococcal diseases caused by non-typeable S. pneumoniae. A meta-analysis was performed to estimate the pooled prevalence of non-typeable S. pneumoniae in pneumococcal diseases. Thirty-four studies conducted in 25 countries spanning four continents were included in the analysis. The pooled prevalence of non-typeable S. pneumoniae in pneumococcal diseases was 8.7% (95% CI [4.6; 13.9]). The pooled prevalence of non-typeable S. pneumoniae was highest in conjunctivitis at 37.6% (95% CI [14.4; 64.4]), followed by meningitis at 5.8% (95% CI [2.7; 9.8]), pneumonia at 5.3% (95% CI [1.8; 10.4]), and otitis media at 0.9% (95% CI [0.2; 2.1]). The pooled prevalence of non-typeable S. pneumoniae in pre-vaccination studies and post-vaccination studies was 5.2% (95% CI [1.7; 10.2]) and 10.9% (95% CI [4.5; 19.6]), respectively. More than 25% of non-typeable pneumococcal isolates were multidrug-resistant. This study presents the first comprehensive global estimate demonstrating a substantial prevalence of non-typeable pneumococcal diseases. Continuous surveillance is essential to monitor trends in non-typeable pneumococcal diseases, informing decisions on disease control and vaccine development.