Diversity of pneumococcal surface protein A (PspA) and relation to sequence typing in Streptococcus pneumoniae causing invasive disease in Chinese children.

The objective of this paper was to investigate the sequence types (STs) and diversity of surface antigen pneumococcal surface protein A (PspA) in 171 invasive Streptococcus pneumoniae isolates from Chinese children. A total of 171 pneumococci isolates were isolated from Chinese children with invasive pneumococcal diseases (IPD) in 11 hospitals between 2006 and 2008. The pneumococci samples were characterized by serotyping, PspA classification, and multilocus sequence typing (MLST). The PspA of these strains could be assigned to two families. The PspA family 2 was the most common (120/171, 70.1%). No PspA family 3 isolates were detected. Family 1 could be subdivided into two clades, with 42 strains in clade 1 and 9 strains in clade 2, and family 2 could be subdivided into clades 3, 4, and 5, which respectively contained 5, 21, and 14 strains. In total, 65 STs were identified, of which ST320 (30/171, 17.5%), ST271 (23/171, 13.5%), and ST876 (18/171, 10.5%) were the most common types. PspA family 2 and family 1 were dominant among pneumococcal clones isolated from Chinese children with invasive disease. The strains with the same ST always presented in the same PspA family.