Prevalence and Clonal Distribution of pcpA, psrP and Pilus-1 among Pediatric Isolates of Streptococcus pneumoniae

Streptococcus pneumoniae is the leading cause of vaccine-preventable deaths globally. The objective of this study was to determine the distribution and clonal type variability of three potential vaccine antigens: Pneumococcal serine-rich repeat protein (PsrP), Pilus-1, and Pneumococcal choline binding protein A (PcpA) among pneumococcal isolates from children with invasive pneumococcal disease and healthy nasopharyngeal carriers. We studied by Real-Time PCR a total of 458 invasive pneumococcal isolates and 89 nasopharyngeal pneumococcal isolates among children (total = 547 strains) collected in Barcelona, Spain, from January 2004 to July 2010. pcpA, psrP and pilus-1 were detected in 92.8%, 51.7 % and 14.4 % of invasive isolates and in 92.1%, 48.3 % and 18 % of carrier isolates, respectively. Within individual serotypes the prevalence of psrP and pilus-1 was highly dependent on the clonal type. pcpA was highly prevalent in all strains with the exception of those belonging to serotype 3 (33.3 % in serotype 3 isolates vs. 95.1 % in other serotypes; P,.001). psrP was significantly more frequent in those serotypes that are less apt to be detected in carriage than in disease; 58.7 % vs. 39.1% P,.001. Antibiotic resistance was associated with the presence of pilus-1 and showed a negative correlation with psrP. These results indicate that PcpA, and subsequently Psrp and Pilus-1 together might be good candidates to be used in