Ore 2000. Complex 2 included 12 MRSA (ASA-404 ST239-spa t030) isolated from 2000 to 2006. Complex 3 included 7 MRSA and mostly ST5. All of the strains in Complex 4 were MSSA. Complex 5 included 3 ST59-MRSA and 2 ST59MSSA. Swine MRSA were clustered in complex 6. The Australian strains were scattered, and 3 out of 6 were in complex 7.system gene hsdS (SAV0432 and SAV1807) were identified in human-specific genes, which confirmed their function in regulating gene horizontal transfer. Three gene clusters (C8, C9 and C10) were distinct from any known genomic islands. Cluster C8 (SAV1312 AV1314) contained three function-unknown genes. Cluster C9 (SAV2481 AV2499) carried two global regulators, sarH2 and sarH3, indicating its potential regulatory function in host specificity. Swine-specific cluster C10 (SAV0028-SAV0035) belonging to plasmid pUB110 contained the resistance gene aadD. The representative genes of 10 clusters associated with host specificity were further analyzed in 76 human MRSA and 20 swine MRSA strains. The presense of representative genes showed significant differences between human and swine MRSA strains (Table 2, P,0.005). Interestingly, not all human MRSA carried human-specific gene clusters identified by our CGH microarray. ST59 MRSA did not carry human-specific clusters C3, C4, and C6, and showed a similar pattern as swine MRSA.Comparative Genomics of MRSA and MSSA StrainsMSSA showed more diverse patterns compared with the relative preponderance of a few MRSA clones. The differences between 6 MSSA and 18 MRSA isolated in China were analyzed, and 75 genes were found to be more frequently present in MRSA. Among these genes, 38 are located at known genomic islands, including SCCmec, vSa4, vSaa and Tn5801 (Table 1 and Fig. 3), which contained several resistance genes such as mecA, ermA, tetM, and ant(9). We also identified a novel MRSA-specific gene cluster C12, which contained 2 resistance genes [ermA and ant(9)], 3 transposase genes, and 1 function-unknown genes. Sequence alignment indicated that C12 had homology with Tn554 of S. epidermidis and may represent a novel resistant island. To determine whether the resistance genes in MRSA isolates differed between lineages, 10 resistance genes in all of the MRSA strains analyzed by microarray were compared (Table 3). The mecA, aphA, dfrA, isaA, msrA, and msrB were Delavirdine (mesylate) biological activity detected in all of the analyzed isolates. The ermA and tetM were absent in human ST59, swine ST9, and several ST5 strains. The ant (9) gene was detected in various lineages: ST239 (n = 20), ST59 (n = 2), and swine ST9 (n = 1), was but absent in all of the ST5 strains. The aadD gene was specific to all of the swine ST9 strains and single ST5 isolate, but absent in the ST239 and ST59 strains. In summary, the ST239 and ST5 MRSA isolates display considerable antimicrobial resistance genotype diversity, with ST239 and ST5 being the most predominant clones in China [1]. To further validate these gene clusters, 48 clinical MRSA and 48 MSSA strains were analyzed by detecting representative genes in these clusters. PCR validation results showed that four representative genes of clusters were detected in most MRSA, but were absent in most MSSA strains (Table 4, P,0.0001).Comparative Genomics of Human and Swine S. aureus StrainsCGH microarray was used to study human- and swine-derived MRSA at the genomic level. A total of 1,851 genes were present in both human and swine strains. A total of 102 genes were associated with host specificity, s.Ore 2000. Complex 2 included 12 MRSA (ST239-spa t030) isolated from 2000 to 2006. Complex 3 included 7 MRSA and mostly ST5. All of the strains in Complex 4 were MSSA. Complex 5 included 3 ST59-MRSA and 2 ST59MSSA. Swine MRSA were clustered in complex 6. The Australian strains were scattered, and 3 out of 6 were in complex 7.system gene hsdS (SAV0432 and SAV1807) were identified in human-specific genes, which confirmed their function in regulating gene horizontal transfer. Three gene clusters (C8, C9 and C10) were distinct from any known genomic islands. Cluster C8 (SAV1312 AV1314) contained three function-unknown genes. Cluster C9 (SAV2481 AV2499) carried two global regulators, sarH2 and sarH3, indicating its potential regulatory function in host specificity. Swine-specific cluster C10 (SAV0028-SAV0035) belonging to plasmid pUB110 contained the resistance gene aadD. The representative genes of 10 clusters associated with host specificity were further analyzed in 76 human MRSA and 20 swine MRSA strains. The presense of representative genes showed significant differences between human and swine MRSA strains (Table 2, P,0.005). Interestingly, not all human MRSA carried human-specific gene clusters identified by our CGH microarray. ST59 MRSA did not carry human-specific clusters C3, C4, and C6, and showed a similar pattern as swine MRSA.Comparative Genomics of MRSA and MSSA StrainsMSSA showed more diverse patterns compared with the relative preponderance of a few MRSA clones. The differences between 6 MSSA and 18 MRSA isolated in China were analyzed, and 75 genes were found to be more frequently present in MRSA. Among these genes, 38 are located at known genomic islands, including SCCmec, vSa4, vSaa and Tn5801 (Table 1 and Fig. 3), which contained several resistance genes such as mecA, ermA, tetM, and ant(9). We also identified a novel MRSA-specific gene cluster C12, which contained 2 resistance genes [ermA and ant(9)], 3 transposase genes, and 1 function-unknown genes. Sequence alignment indicated that C12 had homology with Tn554 of S. epidermidis and may represent a novel resistant island. To determine whether the resistance genes in MRSA isolates differed between lineages, 10 resistance genes in all of the MRSA strains analyzed by microarray were compared (Table 3). The mecA, aphA, dfrA, isaA, msrA, and msrB were detected in all of the analyzed isolates. The ermA and tetM were absent in human ST59, swine ST9, and several ST5 strains. The ant (9) gene was detected in various lineages: ST239 (n = 20), ST59 (n = 2), and swine ST9 (n = 1), was but absent in all of the ST5 strains. The aadD gene was specific to all of the swine ST9 strains and single ST5 isolate, but absent in the ST239 and ST59 strains. In summary, the ST239 and ST5 MRSA isolates display considerable antimicrobial resistance genotype diversity, with ST239 and ST5 being the most predominant clones in China [1]. To further validate these gene clusters, 48 clinical MRSA and 48 MSSA strains were analyzed by detecting representative genes in these clusters. PCR validation results showed that four representative genes of clusters were detected in most MRSA, but were absent in most MSSA strains (Table 4, P,0.0001).Comparative Genomics of Human and Swine S. aureus StrainsCGH microarray was used to study human- and swine-derived MRSA at the genomic level. A total of 1,851 genes were present in both human and swine strains. A total of 102 genes were associated with host specificity, s.
