Serovar-distribution and drug-resistance of Salmonella strains isolated from domestic and imported cases during 1995-1999 in Tokyo

Abstract

A total of 2,277 non-typhoidal Salmonella strains consisting of 1,807 domestic strains and 470 imported strains isolated from sporadic cases during 1995-1999 in Tokyo, were examined regarding their serovar-distibution and their drug-resistance. The serological typing results showed that the domestic strains were classified into 17 O-groups and 99 serovars, and the imported strains were classified into 12 O-groups and 58 serovars. Among the serovars identified, Salmonella serovar Enteritidis (S. Enteritidis), S. Thompson, S. Hadar, S. Infantis, S. Typhimurium, and S. Litchfield were predominant in the domestic strains, whereas S. Enteritidis, S. Anatum, S. Hadar, and S. Weltevreden were predominant in the imported strains. The drug-resistance test using 9 drugs (CP, TC, SM, KM, ABPC, ST, NA, FOM, and NFLX) showed that 34.0% of the domestic strains and 33.0% of the imported strains were resistant to any of the drugs examined. The serovars of a high resistant rate during this period were S. Blockley (100%), S. Hadar (96.6%), S. Typhimurium (63.6%), and S. Enteritidis (62.2%) in the domestic strains and S. Blockley (100%), S. Hadar (97.1%), S. Rissen (88.9%), S. Emek (83.3%), S. Panama (83.3%), and S. Typhimurium (77.8%) in the imported strains. Drug-resistance patterns of the resistant isolates varied to 60 types. Prevalent patterns recognized were SM, TC.SM, TC, TC.SM.KM.ST, TC.SM.KM, and CP.TC.SM.ABPC in the domestic strains and TC.SM, TC, NA, TC.SM.KM.NA, and TC.SM.NA in the imported strains.