[Serovar distribution and drug resistance of Salmonella isolated from imported and domestic cases in 1980-1989 in Tokyo].

A total of 6,816 strains of nontyphoidal Salmonella isolated from oversea travellers (imported cases) and domestic healthy individuals and sporadic cases (domestic cases) in Tokyo from 1980 to 1989 were studied for their serovar distribution and antimicrobial sensitivity. The serological typing results showed that the Salmonella strains were classified into 22 O groups and 156 serovars. Among serovars identified, S. ser. Anatum, S. ser. Derby, S. ser. Blockley, S. ser. Agona and S. ser. Typhimurium were predominant in imported cases, while S. ser. Litchfield, S. ser. Typhimurium, S. ser. Hadar, S. ser. Infantis and S. ser. Thompson were predominant in domestic cases. It was also noticed that isolation rates of S. ser. Hadar and S. ser. Blockley have tended to increase noticeably in recent years in both cases. From antimicrobial sensitivity testing, 739 (28.1%) of 2,628 strains isolated from imported cases and 1,047 (25.0%) of 4,188 strains isolated from domestic cases were found to be resistant to any one of the drugs tested (CP, TC, SM, KM, ABPC, ST, NA, FOM and NFLX). From 1980 to 1983 the resistance rate was less than 20% for both cases and then the rate was increased year by year, and it became greater than 40% in 1989. Serovars of a high resistant rate during this period were S. ser. Hadar (96.3%), S. ser. Blockley (92.0%), S. ser. Typhimurium (75.7%), S. ser. Kentuckey (64.1%), S. ser. Krefeld (59.3%), and S. ser. Panama (58.3%) for the imported cases and S. ser. Hadar (97.5%), S. ser. Blockley (57.4%), S. ser. Litchfield (44.6%), S. ser. Enteritidis (44.4%), S. ser. Muenchen (42.2%) and S. ser. Typhimurium (40.9%) for the domestic cases. Drug resistance patterns of the resistant isolates varied up to as much as 50 patterns. Prevalent patterns recognized were TC.SM, CP.TC.SM.KM, TC, CP.TC.SM.KM.ABPC and SM for imported cases and TC.SM, TC, TC.SM.KM, SM, and CP.TC for the domestic cases. 21(12.4%) of 170 drug resistant strains were isolated from imported cases from 1988 to 1989 were found to have conjugative transmissible R plasmids.