The diversity of blaZ gene as measured by the Simpson index of diversity (SID) was higher for the MRSA collection than for MSSA, although Selleck URMC-099 not statistically significant

due to the partial overlapping of the confidence intervals (SID = 79.18, 95%CI 69.6-88.8 vs SID = 76.09, 95%CI 61.3-90.9, respectively) – see Table 4. Overall, blaZ alleles were more variable in MSSA than in MRSA (14.7 and 11.4 SNP/allele, respectively). As illustrated by the allelic frequency distribution

per MRSA lineage (Figure 1) or the cluster tree of the thirteen blaZ alleles found in our collections (Figure 2), there is no clustering according to genetic lineages, as defined by MLST sequence type and SCCmec type, or MSSA/MRSA phenotype; i.e. the same allele could be detected in different genetic lineages or among MRSA and MSSA, and the same lineage could be characterized by several alleles. In addition, there was also no clear clustering of blaZ allotypes according to geographic origin or isolation date of the MRSA NSC 683864 isolates (see Table 1). Table 3 Characteristics of bla locus alleles Gene Allele No. Frequency SNPc) Amino acid substitutions     MRSA a) MSSA b)   Silent Conservative Missense Nonsense   1 0.43 0.21 0 0 0 0 0   2 0.02 0 1 0 0 1 1   3 0.07 0.04 9 4 2 2 0   4 0.04 0 9 4 2 3 0   5 0.06 0 7 2 2 3 0   6 0.11 0.46 13 8 2 3 0 blaZ 7 0.02 0 12 6 2 4 0   8 0.10 0.04 11 6 2 3 0   9 0.07 0.08 20 9 2 7 0   10 Terminal deoxynucleotidyl transferase 0.04 0.04 19 8 2 7 0   11 0.06 0.04 24 11 3 8 0   12 0 0.04 24 11 2 8 0   13 0 0.04 12 7 2 3 0   1 0.33 0.45 0 0 0 0 0   2 0.15 0.25 6 5 0 1 0   3 0.19 0.15 1 0 0 1 0   4 0.19 0.05

4 3 0 1 0 blaI 5 0.04 0 7 5 0 2 0   6 0.07 0 4 3 0 1 0   7 0.04 0 5 4 0 1 0   8 0 0.05 3 1 1 1 0   9 0 0.05 1 0 0 1 0   1 0.26 0.24 0 0 0 0 0   2 0.07 0 19 9 4 6 0   3 0.10 0 18 7 4 6 0   4 0.07 0.06 35 15 9 10 0   5 0.07 0.18 35 15 7 11 0   6 0.07 0.12 17 6 4 6 0 blaR1 7 0.07 0.06 24 10 7 7 0   8 0.03 0 33 12 6 12 0   9 0.16 0 31 11 6 11 0   10 0.13 0.24 32 12 6 11 0   11 0 0.06 20 9 5 7 0   12 0 0.06 34 16 6 10 0 a) The total number of MRSA strains whose blaZ, blaI and blaR1 genes were analyzed is 54, 27 and 31, respectively.