Abstract
Strains of Salmonella Typhimurium (ST) isolated from cattle on 14 farms in Fukushima Prefecture between 1992 and 2004 were analyzed using molecular epidemiological techniques. There were six kinds of ST drug resistance patterns. The experimental results suggested the possibility that the DT104 strains showed resistance to ampicillin (A), chloramphenicol (C), streptomycin (S), sulfonamides (Su) and tetracycline (T), to ASSuT, and to nalidixic acid (N) added to ACSSuT. One amino acid substitution was identified in GyrA of the N-resistant strain. The ACSSuT kanamycin (K) resistant strain was plasmid (170kbp) mediated drug resistant. The ASSuTK-resistant strain possessed a plasmid (120kbp) closely related to an ST pathogenic plasmid, and the PFGE type also differed greatly from that of the other strains. As 13 or 14 strains exhibited a resistance to four or more drugs, it is necessary, from the point of view of both animal health and public health, to monitor the acquisition of new drug resistance in ST.
