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Clustering Analysis of Salmonella enterica Serovar Typhi Isolates in Korea by PFGE, Ribotyping, and Phage Typing

Kim, Shukho, Kim, Sung-Hun, Park, Jeong-Hyun, Lee, Kyung-Shin, Park, Mi-Sun, Lee, Bok Kwon
Foodborne pathogens & disease 2009 v.6 no.6 pp. 733-738
typhoid fever, Gram-negative bacteria, Salmonella enterica subsp. enterica serovar Typhi, patients, isolation, feces, hematologic tests, carrier state, ribotypes, molecular epidemiology, pulsed-field gel electrophoresis, automatic detection, antibiotic resistance, multiple drug resistance, bacteriophages, food pathogens, bacterial contamination, foodborne illness, South Korea
Salmonella enterica serovar Typhi is a Gram-negative bacterium causing the acute febrile disease typhoid fever. In Korea from 2004 to 2006, a total of 51 Salmonella Typhi isolates were identified in stool and blood from healthy carriers and patients with or without overseas travel histories. In this study, antibiogram, pulsed-field gel electrophoresis (PFGE), and automated ribotyping were performed as molecular epidemiological methods with phage typing as a classical subtyping tool of the isolates. Only two isolates were multidrug resistant and 82.3% of the isolates were susceptible to 16 antimicrobial agents tested. When the dendrogram was created based on the PFGE results, the subtypes could be clustered into five groups by 80% similarity criterion. The PFGE patterns of 31 isolates (60.8%) belonged to Cluster 3, the predominant cluster in the study. Three overseas travel-associated cases were differentiated into Cluster 4 of which three isolates were nalidixic acid or multidrug resistant. Major phage type and ribotype were A and PvuII-436-8-S-6, respectively. This study also showed the prevalence of PFGE Cluster 3 in Korea by clustering analysis and the link between some typhoid cases and travel to Cambodia, India, or Indonesia.