Substantial Records On R428 In Grade By Grade Order

?aureus colonization at each time-point. The OR and p values for the effect of each explanatory variable on the outcome (colonization) were calculated (spss software package version 16.0). The proportion of Italian and Swedish infants yielding a stool culture positive for S.?aureus as a function of age is shown in Fig.?1(a). Few infants were positive for S.?aureus in the 3-day sample, but thereafter colonization rate increased rapidly in both cohorts. Colonization reached a maximum at 2?months of age in the Swedish cohort and at 6?months of age in the Italian cohort, whereafter it decreased significantly in both cohorts (p?0.03 and p?0.01, respectively) (Fig.?1a). The S.?aureus was significantly more often retrieved from Swedish than Italian infants at all time-points between 1 and 8?weeks of age (Fig.?1a). In all, 78% of the Swedish and 66% of the Italian infants had S.?aureus in at least one selleck screening library stool sample during the first year of life (p?0.08). Whereas 23% of the Swedish infants harboured S.?aureus on at least six of the seven culture occasions, this was only true for 4% of the Italian infants (p?0.0001). Similarly, 51% of the Swedish infants were positive on at least four occasions compared with 27% of the Italian infants (p?0.008). We have previously shown that Swedish infants R428 price who were positive for S.?aureus in repeated cultures usually harboured a single strain that persisted over several months in the microbiota. Here we performed RAPD analysis on a subsample of 25 Italian and 25 Swedish culture-positive infants to determine whether S.?aureus isolates found in repeated cultures belonged to the same strain or not. In infants harbouring the same strain on at least two time-points (21/25 in both cohorts), the strains persisted for an average of 6.9 and 8.1?months in the Italian and Swedish cohorts, respectively (p?0.34). Averages of 1.6 and 1.3 strains were detected per infant (p?0.14). In vitro production of the superantigenic toxins SEA to SED and TSST-1 was assessed in the strains identified in the 25 Italian and Swedish infants (Table?2). Production of more than one toxin, most commonly SEA and TSST-1, occurred in nine of 39 strains colonizing Italian infants E-64 compared with two of 33 strains from Swedish infants. SEC production characterized most Swedish toxin-positive strains. Population counts of S.?aureus in culture-positive infants are shown in Fig.?1(b). In both cohorts, S.?aureus averaged 107?CFU/g faeces in 1-week-old infants, but declined progressively to 104?CFU/g 12?months of age (p?