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Streptococcus pneumoniae  remains a major agent of invasive diseases, especially in children and the elderly. The presence of pneumococcal capsule, pneumococcal surface protein A (PspA), and pilus type 1 (PI-1) and the ability of colony phase variation are assumed to play important roles in the virulence potential of this microorganism. Differences in the capsular polysaccharide allow the characterization of more than 90 pneumococcal serotypes; among them, serotype 14 and serogroup 9 stand out due to their prevalence in the pre- pneumococcal conjugate vaccine era and frequent association with penicillin non-susceptibility. Here we investigated the distribution of PI-1 and  psp A genes and colony phase variants among 315  S. pneumoniae  isolates belonging to serotype 14 and serogroup 9, recovered over 20 years in Brazil, and correlated these characteristics with penicillin susceptibility and genotype as determined by multilocus sequence typing. All strains were shown to carry  psp A genes, with those of family 2 ( psp A2) being the most common, and nearly half of the strains harbored P1-1 genes. The  psp A gene family and the presence of PI-1 genes were conserved features among strains belonging to a given clone. A trend for increasing the occurrence of  psp A2 and PI-1 genes over the period of investigation was observed, and it coincided with the dissemination of CC156 (Spain 9 V  -3) clone in Brazil, suggesting a role for these virulence attributes in the establishment and the persistence of this successful clone. Opaque variant was the colony phenotype most frequently observed, regardless of clonal type. On the other hand, the transparent variant was more commonly associated with penicillin-non-susceptible pneumococci and with strains presenting evidence of recombination events involving the genes coding for polysaccharide capsule and PspA, suggesting that pneumococcal transparent variants may present a higher ability to acquire exogenous DNA. The results bring to light new information about the virulence potentials of serotype 14 and serogroup 9  S. pneumoniae  isolates representing the major clones that have been associated with the emergence and the dissemination of antimicrobial resistance in our setting since the late 1980s.

frontiers in microbiology

Virulence-Associated Characteristics of Serotype 14 and Serogroup 9 Streptococcus pneumoniae Clones Circulating in Brazil: Association of Penicillin Non-susceptibility With Transparent Colony Phenotype Variants