The GenBank accession number for the J1 region sequence, determined
in this study, is AB627957. Based on the J1 region sequence, we designed a PCR primer set, L2F (5′-GATTAAAACAACTCTCCCAA-3′) and L1R (5′-ATAACCGATTGACCATACAA-3′), thus generating a 363-bp PCR product, for detection of SCCmecIV of ST8 CA-MRSA (tentatively designated SCCmecIVl). We performed PCR detection of 45 staphylococcal Everolimus virulence genes using previously described methods (16); the target genes included three leukocidin genes, five hemolysin genes, 19 SE or related genes, three exfoliative toxin genes, epidermal cell differentiation inhibitor Edin gene, and 14 adhesin genes. When required, we determined the gene sequences; we determined the entire seb gene sequence as described previously
(21). The GenBank accession number for the seb2 gene sequence, determined in this study, is AB630021. We performed PFGE analysis as described previously (14). We performed susceptibility testing of bacterial strains for 36 drugs by the agar dilution method according to previously described procedures (4). Breakpoints for drug resistance were those described by the CLSI (4). Of 349 trains examined, eight (2.3%) were positive for MRSA. The MRSA strains were all isolated from different EPZ015666 mw surfaces or subway train lines and at different times; although three cars per train were
swabbed, there were no cases of multiple cars in the same train positive for MRSA. Isolation place/year, molecular characteristics, and identities of the isolated MRSA are summarized in Table 1. PFGE patterns and computer-assisted comparison are shown in Figure from 1. Two strains (PT1 and PT2) belonged to ST5. PT1 resembles the pandemic New York/Japan clone (Japanese type) having the following typical characteristics (11, 14, 16, 24): (i) it was positive for the pathogenicity island (SaPIm1/n1), which carries three superantigen genes, tst (encodes for toxic shock syndrome toxin 1), sec (encodes for SEC), and sel (encodes for SEL); (ii) it expressed a high degree of oxacillin and imipenem resistance (MICs, ≥ 256 and 64 μg/mL, respectively); and (iii) it was resistant to multiple drugs, including levofloxacin and fosfomycin. The other ST5 strain (PT2) was a variant of the New York/Japan clone (Table 1 and Fig. 1): (i) it exhibited spa14 (t214); (ii) it lacked SaPIm1/n1, like the USA type (16, 24); and (iii) it was unusually positive for seb (encodes for SEB). SEB suppresses the mobility of polymorphonuclear neutrophils by inhibiting expression of staphylococcal exoproteins, allowing MRSA to invade and damage tissues (22).