Table 1.
Resistance patterns of ST59 CA-MRSA strains isolated in Taiwan, compared to ST59 MRSA USA1000.
Figure 1.
Genome comparisons of ST59 MRSA strain PM1 with two other S. aureus genomes.
In A, two gray circles show the complete genomes of ST8 CA-MRSA strain USA300 FPR3757 (2,872,769 bp) and ST398 MRSA strain S0385 (2,872,582 bp); gaps in the genome circles indicate USA300 or S0385 sequences not present in PM1. The sasK gene with the MESPM1 integration site (att) is shown outside the gray circles (on the USA1000 genome circle), since the USA300 and S0385 MRSA strains do not possess the sasK gene. The outermost (white) circle represents the alignment of PM1 contigs and provides PM1 genome information, including drug resistance traits, pathogenetic islands, bacteriophages, and genomic islands νSAα and νSAβ. Plasmid pPM1 is shown in the right bottom of the figure. Color region in the genome: orange, orfX with the att sequence for SCCmec; green, genetic elements with diversity; brown, genetic elements present in USA300 or S0385 (but not in PM1); pink, genetic elements present in PM1 (but not in USA300 or S0385). In B, relevant genotypes of PM1 is summarized. Drug resistance (r): Ery/Cli, erythromycin/clindamycin; Kan, kanamycin; Stm, streptomycin; Chl, chloramphenicol; Oxa, oxacillin; Tet, tetracycline. Virulence factors: SEB, staphylococcal enterotoxin B; SEK, staphylococcal enterotoxin K; SEQ, staphylococcal enterotoxin Q; PVL, Panton-Valentine leukocidin.
Figure 2.
Genetic structure of MESPM1 carrying four resistance genes, ermB, aph(3′)-IIIa, aadE, and cat.
MESPM1 was integrated into and disrupted the sasK gene, which encoded a putative cell-wall anchored surface protein with the LPXTG-motif. The intact sasK gene was present in PVL-positive ST59 CA-MRSA type strain USA1000. Three att sites are in a vertical red line. The region of IS1216V with the transposase gene (tnp) is shaded in blue. Homology regions with E. faecalis pLG2 plasmid (GenBank accession number HQ426665) and S. aureus SAP084A (GenBank accession number GQ900436) are shaded in yellow and purple, respectively. A Greek delta symbol indicates truncated coding sequence.
Figure 3.
The structure of MESPM1 and its segregants in ST59 CA-MRSA strains.
Structures of MESPM1, MESPM9, MESPM8, and MESPM18 (corresponding to IS1216V) are shown in A to D. Drug resistance (r): Ery/Cli, erythromycin/clindamycin; Kan, kanamycin; Stm, streptomycin; Chl, chloramphenicol. The IS1216V region with the transposase gene (tnp) is shaded in blue. The att site is indicated by a vertical red line. Arrows below the MES structures indicate PCR primers, which are listed in Materials and Methods.
Figure 4.
Genetic structure of penicillinase plasmid pPM1 and its segregant.
In A, pPM1 structure is shown. Inner circle indicates homologous regions to S. aureus plasmid SAP014A (GenBank accession number GQ900379), SAP063A (GenBank accession number GQ900418), and pSK156 (GenBank accession number GQ900448). The IS431 region with the transposase gene (tnp) is shaded in light green. A Greek delta symbol indicates truncated coding sequence. In B, a segregant of pPM1 in MEStet locus is shown. Tetr, tetracycline-resistant; Tets, tetracycline-susceptible.
Table 2.
Transfer of drug resistance in mating between ST59 CA-MRSA strain PM1and S. aureus RN2677.
Figure 5.
The 15,551-bp νSAβ structure in PM1 is shown in the upper part. This sequence was compared to the data of ST8 CA-MRSA strain USA300 FPR3757 (GenBank accession number NC_007793) and ST5 HA-MRSA strain N315 (GenBank accession number BA000018). PM1 regions homologous to φSA3USA (of USA300) and νSAβs (of USA300 and N315) are shaded in pink and yellow, respectively. A Greek delta symbol indicates truncated coding sequence.
Figure 6.
Comparison of IS1216V-containig mobile elements in MRSA and E. faecium.
The structures of IS1216V-containing mobile elements: A, MESPM1 determined in this study; B, Tn1546 and Tn5506 in E. faecium; C, vancomycin resistance transposon Tn1546 in VRSA. The IS1216V region with the transposase gene (tnp) is shaded in blue. The att site is indicated by a vertical red line. The data for pVEF1 are from GenBank (GenBank accession number AM296544). The data for pHKK701 and Tn1546 in VRSA-2 and VRSA-3 were obtained from previously described maps [31], [32].
Table 3.
Primers used for PCR mapping of the MESPM1 locus.