Article Figures & Data
Figures
- Fig. 1.
Schematic representation of the mecA,mecR1, and mecI genes and locations of primers (Table 1) used in this study. The direction of the nucleotide extension reaction (5′ to 3′) of each primer is shown by a solid arrow. The shaded arrows indicate the directions of transcription of the structural genes.
- Fig. 2.
(A) Partial nucleotide sequences of the mecIgene from prototype S. aureus N315 (5) and MRSA SH13. Presumptive nucleotide sequences which were deleted in the SH13mecI gene are underlined. Triple asterisks under themecI gene sequence of strain SH13 denote a putative stop codon caused by the deletion. (B) Nucleotide sequence of themecA promoter region. Positions of base substitution (M6 and M7) are shown by solid arrows. Putative −35 and −10 promoter sequences and Shine-Dalgarno (SD) sequences are shown by dotted lines, and a pair of palindrome sequences are indicated by solid lines above the sequence. The direction of mecA gene transcription is shown by a shaded arrow, with the initiation codon indicated by solid underlining.
Tables
- Table 1.
Properties of MRSA strains analyzed in this study
Year of isolation Strain Coagulase typea RFLP pattern of coagulase geneb MIC (μg/ml) of oxacillinc RFLP pattern ofmecI gened 1993 SH1 II A 256 1 SH12 II A 256 1 SH13 II A 256 3 SH19651 IV C 256 2 SH15 IV C 1,024 2 SH20 II A 1,024 1 SH22 VII B 1,024 1 SH24 II A 256 1 SH27 II A 256 1 1994 SH153 II A 256 1 SH155 II A 512 1 SH158 II A 256 1 SH165 II A 512 1 SH212 II A 512 2 1995 SH219 II A 256 1 SH320 II A 256 1 SH321 II A 256 1 SH324 II A 512 1 SH326 II A 512 1 SH327 II A 512 1 ↵a Coagulase type (I to VIII) was determined with coagulase type-specific antisera.
↵b RFLP patterns based on the staphylocoagulase gene were classified as described previously (11).
↵c Susceptibility to oxacillin was measured by a broth microdilution assay with cation-supplemented Mueller-Hinton broth (BBL) containing 2% NaCl as recommended by the National Committee for Clinical Laboratory Standards (15).
↵d Differentiation of the RFLP patterns to detect mutation in the mecI gene was performed as described previously (12; see text).
- Table 2.
Oligonucleotide primers
Primer name Sequencea mecI1 5′-AATGGCGAAAAAGCACAACA-3′ mecI2 5′-GACTTGATTGTTTCCTCTGTT-3′ mecI3 5′-GCACAACAAATTTCTGAGCG-3′ mecI4 5′-TGGACTCCAGTCCTTTTGC-3′ mecI5 5′-CTTGTAGAAGAAAGTGATAT-3′ Pr-mecA 5′-CCTGTATTGGCCAATTCCAC-3′ Pr-mecR 5′-AATGGAATTAACGTGGAGAC-3′ ↵a The location of each primer onmec DNA is shown in Fig. 1.
- Table 3.
Mutations detected in mecI gene andmecA promoter region of MRSA strains
Mutation group MRSA strain(s) Mutation in mecI gene Mutation in mecA promoter regiona Nucleotide position change Codon change M1 SH20 43 (G→T) Val15→Phe None M2 SH22 163 (A→T) Lys55→stop codon None M3 SH15, SH19651 202 (C→T) Gln68→stop codon None M4 SH212 202 (C→T) Gln68→stop codon C→A M5 SH13 Deletion of 28 bases (28–55 or 29–56)b Stop codon after the 11th amino acid None M6 SH1, SH12, SH24, SH27, SH153, SH158, SH165, SH219, SH320, SH321, SH324, SH326, SH327 None None C→A M7 SH155 None None G→A
