001), but no synergistic effect between the two genes was observed, since the presence of one did not significantly increase the representation of the other among invasive isolates. In contrast, speC (P = 0.002), ssa (P < 0.001), and speL/M (P < 0.001) were individually associated with pharyngitis. The combinations speC+speL/M and ssa+speL/M were both associated with pharyngitis (P = 0.004 and 0.012, respectively), but there was also no synergistic effect relative to the presence of a single gene. However, the association of speC with
pharyngitis selleck chemicals llc isolates can be explained by a high frequency of co-occurrence of this gene with ssa, since the isolates harboring speC without ssa were PCI-34051 mw not significantly associated with any of the groups. An interesting situation occurred when analyzing the interaction between speJ (associated with invasive infections) and ssa (associated with pharyngitis). Among isolates carrying speJ, the group that also carried ssa was no longer associated with invasive
infections, while the association of isolates carrying ssa with pharyngitis was not significantly altered by the presence of speJ. This argues for a dominant effect of the presence of ssa over that of speJ in determining the invasive capacity of individual isolates. The association of SAg profiles with disease presentation was also tested. Two SAg profiles Crenolanib mw presented a significant association with invasive isolates, namely SAg10 (speA + speG + speJ + smeZ +) and SAg46 (speG + smeZ Branched chain aminotransferase +) (P < 0.001). The remaining profiles were not significantly associated with any of
the two groups of isolates. When the same kind of analysis was performed for emm types and individual SAg genes, three combinations with statistical significance emerged: the association of isolates presenting emm1 and speA, and emm1 and speJ with invasive infections (P < 0.001), and the association of isolates carrying emm75 and speL/M with pharyngitis (P = 0.001). In all cases, no synergistic or antagonistic interaction was detected between emm type and SAg gene, since the emm type did not alter the association of the SAg gene with a particular group of isolates. Differences between the PFGE clusters found among invasive infection and pharyngitis The associations described above can be correlated with the PFGE clusters which were also different between the invasive and pharyngitis groups of isolates (P < 0.001), in agreement with the differences found in emm types (Figure 1 and Figure 2). All the 19 major PFGE clusters occurred in both invasive and pharyngitis isolates, except for R6 (emm75-T25-ST150-SAg39), which was present only among pharyngeal isolates, but the difference did not reach statistical significance due to the small number of isolates in this cluster. PFGE distinguished several groups of isolates belonging to emm types 1 and 4.