the dominance of pilus islet 1 in pneumococcal isolates collected from patients and healthy individuals

background: pili in streptococcus pneumoniae have been shown to be one of the adherence factors for epithelial cells in the human upper respiratory tract. two types of pilus-like structures (pilus islet-1 and pilus islet-2) have been distinguished in s. pneumoniae. objectives: to investigate the presence of pilus islet-1 (pi-1) in s. pneumoniae and the correlation between our isolates. materials and methods: in this study, 162 s. pneumoniae isolates were collected from clinical specimens, and normal flora were also examined for the distribution of pi-1 using the presence of the rlra and rrgc genes as markers for this islet and sipa as an indicator of pilus islet-2 (pi-2). box-pcr analyses were performed to determine the genetic relationship between isolates. results: the results confirmed the presence of rlra and rrgc genes in both clinical (n = 39) and normal flora (n = 26) isolates. the minimal inhibitory concentration results revealed that the rate of resistance of these isolates to the three antibiotics tested ranged from 26% for penicillin to 46% for erythromycin and tetracycline. furthermore, 12% of the isolates were resistant to all three antibiotics. strain typing using repetitive element box-pcr analysis among the 65 isolates identified 8 different band patterns. conclusions: our results indicated that the dissemination of pi-1 was widespread in s. pneumoniae isolates, although no pi-2 isolates were detected. furthermore, the frequency of rlra and rrgc of clinical isolates was significantly more than that of normal flora isolates.