The prevalence of pilus islets in Streptococcus pneumoniae isolates from healthy children in Indonesia

Streptococcus pneumoniae produces pili that function as adherence factors to bind to epithelial cells in the human upper respiratory tract. In this study, we investigated the prevalence of pilus islets (PIs) in S. pneumoniae strains carried by healthy children below 5 years of age prior to pneumococcal vaccination in 2012 in Lombok Island, Indonesia. In all, 347 archived S. pneumoniae isolates were screened using polymerase chain reactions for the presence of rrgC and pitB genes representing pilus islet 1 (PI-1) and pilus islet 2 (PI-2), respectively. We found that 40 isolates (11.5 %) contained the PI genes: 5.2% carried both PI-1 and PI-2, and 3.5 and 2.9% carried PI-1 and PI-2, respectively. Furthermore, we found that most of the strains carrying either of the PIs belonged to the vaccine serotypes 19F and 19A and were less susceptible to chloramphenicol and tetracycline.