However, this locus exhibited selleckchem a D value of 0.43 with an allele number of seven and thus significantly contributed to the genotyping of the O26 isolates. As such, three loci (EH111-8, EH111-11, and EH111-14) were specifically present in O111 but were of a certain level of usefulness for this serogroup because they exhibited moderate D values (0.21, 0.24, and 0.17, respectively). Our results indicate that these four loci can be used for genotyping the O26 and O111 isolates. Figure 1b shows the results of our evaluation of the 18 loci for the isolates belonging to all the three serogroups together. The allele numbers ranged from 3 to 45, and the D values ranged from 0.34 to 0.92. In this analysis, six loci (EH157-12, O157-34, O157-37,

O157-9, EHC-1, and EHC-2) exhibited higher D values than did the other loci. The overall D values were 0.991 (95% CI = 0.989–0.993), 0.988 (95% CI = 0.986–0.990), and 0.986 (95% CI = 0.979–0.993) for the O26,

O111, and O157 isolates, respectively. These values indicate that our system is useful for genotyping EHEC isolates of not only the O157, but also the O26 and O111 serogroups. As the results mentioned above indicated BGJ398 nmr that our expanded MLVA system was useful for genotyping the O26 and O111 isolates, we next carried out cluster analyses of the O26 and O111 isolates by using the new MLVA system. In this analysis, we included the isolates collected during nine O26 outbreaks and three O111 outbreaks, as Methocarbamol well as assessing the applicability of our system for detecting outbreak-related strains in these two serogroups. As shown in Figure 3, the isolates

collected during each of the 12 outbreaks formed unique clusters. Isolates from three outbreaks (26OB5, 26OB6, and 111OB3 outbreaks) did not exhibit any repeat copy number variations for all 18 loci. With regard to the other nine outbreaks, variations were observed for some loci in a few isolates obtained during the same outbreak (Table 2). However, in eight of the nine outbreaks, variations were mainly found in the O157-37 and/or EHC-6 loci, both of which are located in large plasmids, such as pO157, suggesting that entire plasmids may have been lost or parts of these plasmids may have been deleted in some strains during the outbreaks or after strain isolation. These results indicate that the MLVA system can be useful for detecting outbreaks of the EHEC strains belonging to the O26 and O111 serogroups. The O26 and O111 isolates were also subjected to cluster analyses based on PFGE profiles (Fig. 4). Each of the outbreaks formed a unique cluster, as shown in Figure 3. The relative positions of the PFGE-based clusters, however, did not always match those of the MLVA-based clusters. For example, the positions of the clusters of 26OB3 and 26OB7 in the PFGE analysis were closely matched; however, their positions were completely different in the MLVA. Moreover, the subtypes within a cluster defined in each method did not completely match.