ackground: It is difficult to control an outbreak of Shigella infection, because of the ease of transmission and the resistance to multiple antibiotics. Recently, there were outbreaks of Shigella infection in Chinju area. The objective of this study was to investigate the molecular epidemiology of the outbreaks using pulsed-field gel electrophoresis (PFGE).

Method: Thirteen S. flexneri strains, 25 S. sonnei strains from Chinju and 15 S. sonnei strains from Pusan were studied. All strains were isolated from stool cultures of diarrheal patients. Identification and antimicrobial susceptibility test of those were tested by Vitek GNI and GNS-LH. Chromosomal DNA restricted with XbaI was resolved by PFGE.

Result: All the S. flexneri strains and 23 (92%) S. sonnei strains from Chinju were resistant to one or more antimicrobial agents. All the clinical isolates of S. flexneri showed the same PFGE pattern which was different from type strain (KTCC 2517). PFGE patterns of 25 (100%) S. sonnei strains from Chinju and 12 (80%) S. sonnei strains from Pusan were identical to those of type strain (KTCC 2009). Three S. sonnei strains from Pusan showed distinct PFGE patterns, respectively.

Conclusion: PFGE demonstrated identical restriction pattern among most of Shigella isolates from Chinju and Pusan, indicating that an outbreak with genetically related strains had occurred. PFGE was useful for molecular epidemiology of Shigella outbreaks. (Korean J Clin Microbiol 2000;3(1):23-29)