Puzzling Over the Pneumococcal Pangenome

Abstract

The Gram positive bacterium Streptococcus pneumoniae (pneumococcus) is a major human pathogen. It is a common colonizer of the human host, and in the nasopharynx, sinus, and middle ear it survives as a biofilm. This mode of growth is optimal for multi-strain colonization and genetic exchange. Over the last decades, the far-reaching use of antibiotics and the widespread implementation of pneumococcal multivalent conjugate vaccines have posed considerable selective pressure on pneumococci. This scenario provides an exceptional opportunity to study the evolution of the pangenome of a clinically important bacterium, and has the potential to serve as a case study for other species. The goal of this review is to highlight key findings in the studies of pneumococcal genomic diversity and plasticity.

Serotype Distribution and Antimicrobial Susceptibility of Streptococcus pneumoniae in Pre- and Post- PCV7/13 Eras, Taiwan, 2002–2018

“…The selection pressure of pneumococcal vaccine leads to dynamic changes in serotype distribution with subsequent emergence of NVTs (Hiller and Sa-Leao, 2018;Lo et al, 2019;Ouldali et al, 2019). Our surveillance data together with worldwide reports indicated the need of extending vaccine polyvalency.…”

“…Because changes in pneumococcal antimicrobial susceptibility and ongoing serotype replacement with emergence of new resistance lineages could occur under antibiotic and vaccine selective pressures (Hiller and Sa-Leao, 2018;Lo et al, 2019;Ouldali et al, 2019;Pinto et al, 2019), the World Health Organization (WHO) recommends that surveillance of pneumococcal infection should be continued for at least 5 years after implementation of PCV. The Taiwan Surveillance of Antimicrobial Resistance (TSAR) is a longitudinal multicenter surveillance program of clinical isolates to monitor the molecular epidemiology of bacterial pathogens and their trends of antimicrobial resistance (Huang et al, 2014;Wu et al, 2017).…”

Whole Genomic Comparative Analysis of Streptococcus Pneumoniae Serotype 1 Isolates Causing Invasive and Non-Invasive Infections Among Children Under 5 years in Casablanca, Morocco

“…The pangenome analysis by Roary revealed a total of 1805 accessory genes found in 0% <= strains < 99% of the 80 strains analyzed. Those genes are mainly associated with evasion of the host immune system and virulence factors [21]. Nevertheless, our ndings showed that the accessory genomes in invasive sublineages were substantially smaller.…”

Lysogeny in Streptococcus pneumoniae

“…Contradictory findings on the role of phages in colonization and disease are perhaps not unforeseen given the wide genetic diversity of pneumococcal phages and the extraordinary plasticity of the pneumococcal genome, where the core genome constitutes merely a quarter of the pneumococcal pangenome [ 81 ]. It is thus likely that more factors than the simple presence of a phage, or a specific phage-encoded feature such as PblB, are at play.…”