Characterisation of meticillin-resistant Staphylococcus aureus ST97 and ST5 isolated from pigs in Japan.

The objective of this study was to determine the frequency and clonal types of meticillin-resistant Staphylococcus aureus (MRSA) among slaughter pigs in a top pig-producing area in Japan. In total, 100 nasal swabs were collected from slaughterhouse pigs originating from 21 different farms. MRSA isolates were analysed by staphylococcal cassette chromosome mec (SCCmec) typing, spa typing and multilocus sequence typing (MLST) and were examined for susceptibility to nine antimicrobial agents (ampicillin, oxacillin, gentamicin, kanamycin, erythromycin, clindamycin, vancomycin, ciprofloxacin and tetracycline). MRSA isolates were obtained from eight swabs (8%), representing three pig farms (14%). Five of the isolates were classified as ST97/spa t1236/SCCmec V and three were classified as ST5/spa t002/atypical SCCmec type. All of the isolates were resistant to ampicillin, oxacillin and tetracycline, and seven isolates (88%) were resistant to clindamycin. The five ST97 MRSA isolates displayed an unusual phenotype (clindamycin-resistant/erythromycin-susceptible). In conclusion, this is the first report of a ST97 MRSA isolate in Japan. The overall prevalence of MRSA is low in pigs, although it appears to be adapting among pigs in Japan owing to the new ST97 and ST5 MRSA strains.

Design and synthesis of rho kinase inhibitors (III).

The structure-activity relationship of Rho kinase inhibitors bearing an isoquinoline scaffold was studied. N-(1-Benzyl-3-pyrrolidyl)-N-(5-isoquinolyl)amine analogues were optimized with respect to their inhibitory potencies for the enzyme and for chemotaxis. The potent analogues were further evaluated by an ex vivo test in which the selected compounds were orally administered to rats, and the Rho kinase inhibitory potency observed in the rat serum was evaluated 3h after the administration. Compound 23g showed a high level of Rho kinase inhibitory activity in the rat serum and was stable in an in vitro metabolic test using a microsomal cytochrome preparation. The (R)-isomer of 23g displayed a higher level of inhibitory potency than the (S)-isomer in a cell-free kinase assay and in the cell migration assay (IC(50)(ENZ)=25 nM and IC(50)(MCP)=1 microM). The (R)-isomer successfully inhibited the phosphorylation of MBS (myosin-binding subunit) in cells.

Design and synthesis of Rho kinase inhibitors (II).

In a previous study, we identified several structurally unrelated scaffolds of the Rho kinase inhibitor using pharmacophore information obtained from the results of a high-throughput screening and structural information from a homology model of Rho kinase. 1H-Indazole is one of the candidate scaffolds on which a new series of potent Rho kinase inhibitors could be developed. In this study, the detailed structure-activity relationship of 1H-indazole analogues was studied. During this study, we found that the cell-free enzyme inhibitory potential of Rho kinase inhibitors having the 1H-indazole scaffold did not necessarily correlate with their inhibitory potential toward the chemotaxis of cultured cells. The choice of the linker substructure was shown to be an important factor for the 1H-indazole analogues to inhibit the chemotaxis of cells. Optimization of the 1H-indazole inhibitors with respect to the in vitro inhibition of monocyte chemotaxis induced by MCP-1 was carried out. The inhibitory potential was improved both in the cell-free enzyme assay and in the chemotaxis assay.