DETECTION OF THE H1-J STRAIN OF SALMONELLA-TYPHI AMONG KOREAN ISOLATES BY THE POLYMERASE CHAIN-REACTION

Salmonella typhi, the etiologic agent of typhoid fever, typically has only a phase-1 flagellar antigen, H1-d (fliC). While most strains of S . typhi have H1-d antigen, 10-20% of Indonesian isolates have been rep orted to possess H1-j antigen instead. To investigate the presence H1- j strains of S. typhi isolates in Korea, where typhoid fever is still a common infectious problem, we used the polymerase chain reaction (PC R) with a pair of oligonucleotides primers that specifically amplified the flagellin gene of S. typhi. Of 375 isolates of S. typhi tested, o nly one was shown to possess the H1-j antigen, which was shown by the presence of a 1,269-basepair fragment on agarose gel electrophoresis a fter the PCR. The isolate with the H1-j antigen was cultured from a Ko rean-Indonesian man who was already symptomatic in Indonesia and was t hought to be an Indonesian strain. Because 375 strains tested in this study were collected from cases with typhoid fever in different region s of Korea during the period from 1986 to 1991, it could be concluded that the mutation rate to j antigen is negligible among S. typhi endem ic in Korea.