Capsular types targeted by PCV7 (4, 6B, 9V, 14, 18C, 19F, and 23F) were classified as VT. Isolates expressing capsular types not included in PCV7 and non-typeable

isolates were classified as NVT. PFGE was performed according to a previously described protocol [28] after digestion of total DNA with SmaI (New England Biolabs) using as molecular weight standards the pneumococcal isolate R6 and the PFGE λ marker (New England Biolabs). In order to screen for putative capsular switch events, PFGE patterns of representative isolates were compared. PF-02341066 datasheet To this end, one isolate for each serotype observed in a given child per sampling period was randomly selected. Analysis of association between vaccination state and pneumococcal colonization was performed by calculating the odds ratio (OR), and statistical significance was assessed with χ2 test or Fisher’s exact test when appropriate. A maximum type I error of 0.05 was considered for recognition of a significant vaccination effect. All children of the vaccinated and control groups enrolled in this study yielded two nasopharyngeal swabs, the first in May 2001 and the second in June 2001. The average number http://www.selleckchem.com/products/Erlotinib-Hydrochloride.html of isolates per swab was 9 (range, 1–10) and the mode was 10. Overall, we isolated and serotyped 1224 pneumococci, and the PFGE profile for representative isolates of each serotype was determined. In both the vaccinated and control

groups the overall prevalence of single and multiple carrier children, as well as the number of pneumococcal isolates, was similar (P > 0.05) in the two sampling periods ( Table 1). Regarding the vaccinated group, in May 2001 (pre-vaccine sampling period), among the 430 pneumococcal isolates recovered from single carriers, 13 serotypes were

identified although four VT serotypes (6B, 14, 19F, and 23F) accounted for the majority of the isolates (60%) (Table 2). In June 2001, 1 month after vaccination with a single PCV7 dose, 14 serotypes were identified among Levetiracetam the 430 pneumococcal isolates recovered. The frequency of VT serotypes decreased from 60 to 39%, while the frequency of NVT isolates increased from 40 to 61% (P < 0.001) ( Table 2). Concerning the control group, in May 2001, among the 110 pneumococcal isolates recovered from single carriers, five serotypes were identified of which three VT serotypes (6B, 19F, and 23F) accounted for the majority of the isolates (64%) ( Table 2). In June 2001, six serotypes were identified among the 100 pneumococcal isolates recovered. The frequency of VT serotypes (6B, 14, 19F, and 23F) increased from 64 to 70%, while the frequency of NVT isolates decreased from 36 to 30% (P = 0.328) ( Table 2). In the vaccinated group, among the 65 pneumococcal isolates recovered from multiple carriers in May 2001 (pre-vaccine), 10 serotypes were identified, of which four VT serotypes (6B, 14, 19F, and 23F) represented 45% of the isolates (Table 3).