Genotyping of invasive Streptococcus pneumoniae serotype 19A and 19F in China

Objective To investigate the genotypes of invasive Streptococcus pneumoniae serotype 19A and 19F in China. Methods A total of 57 invasive S. pneumoniae isolates,including 35 serotype 19A strains and 22 serotype 19F strains,were collected through laboratory-based bacterial vaccine preventable disease surveillance network of China. All the isolates were serotyped quellung and PCR. Multilocus sequence typing(MLST)was used for genotyping. Cluster analysis was performed by using software BioNumerics. Results There were 6 STs among 35 invasive S. pneumoniae serotype 19A strains. The predominant sequence type was ST320(n=29,82.9%),followed by ST876(n=2,5.7%),ST4560(n=1,2.9%),ST9230 (n=1,2.9%),ST7759(n=1,2.9%)and ST6429(n=1,2.9%). There were 7 STs among 22 invasive S. pneumoniae serotype 19F strains,including ST271(n=14,63.6%),ST236(n=1,4.5%),ST320(n=2,9.1%),ST1937(n=2,9.1%), ST6993(n=1,4.5%),ST9236(n=1,4.5%)and ST9240(n=1,4.5%). The predominant sequence type was ST271. Conclusion ST320 was the predominant genotype of invasive S. pneumoniae serotype 19A strains. The predominant genotype of 19F invasive strains was ST271. Both the serotype 19A strains and serotype 19F strains had same genotype ST320.