title: A virulent strain of Salmonella enterica serovar London isolated in infants with enteritis traced by active surveillance and molecular epidemiological study.
abstract: A total of 74 isolates of Salmonella enterica serovar London were collected through the Laboratory-Based Diarrheal Diseases Surveillance in 2000-2001. In order to characterize the isolates and investigate the source of the epidemic, we performed antimicrobial susceptibility tests and XbaI Pulsed-field gel electrophoresis (PFGE) of 44 Salmonella London isolates. Forty isolates were from feces of infants and four isolates were from adults aged 30, 52, 54, and 59 yr. Two subtypes were identified: a tetracycline-susceptible A 0 PFGE pattern and a tetracyclineresistant A 1 PFGE pattern. Interestingly, the isolates from all infants and one 30-yr-old adult were A 0 PFGE pattern and tetracycline-susceptible. Furthermore, the A 0 PFGE pattern strain was approximately 2 times more virulent than the A 1 PFGE pattern strain, according to the results of in vitro invasion assay using J774A.1 macrophage-like cells. These results indicate that the active surveillance with molecular epidemiological tools would be valuable for promptly finding new epidemic strains. Our results also suggested that the virulent Salmonella London strain might infect the infants through a common contaminated source.
authors.affiliation: Department of Microbiology, National Institute of Health, 5 Nokbun-dong, Eunpyung-gu, Seoul, Korea.
authors.forename: Shukho
authors.initials: S
authors.lastname: Kim
authors.forename: Bok Kwon
authors.initials: BK
authors.lastname: Lee
authors.forename: Yeon Ho
authors.initials: YH
authors.lastname: Kang
authors.forename: Hee Jung
authors.initials: HJ
authors.lastname: Nam
authors.forename: Ok Young
authors.initials: OY
authors.lastname: Lim
authors.forename: Won Seok
authors.initials: WS
authors.lastname: Seok
authors.forename: Jae Ku
authors.initials: JK
authors.lastname: Park
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D004269:DNA, Bacterial / Q000032:analysis; D003967:Diarrhea / Q000453:epidemiology / Q000382:microbiology; D004196:Disease Outbreaks; D004751:Enteritis / Q000453:epidemiology* / Q000382:microbiology; D005243:Feces / Q000382:microbiology; D006801:Humans; D066298:In Vitro Techniques; D007223:Infant; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D017382:Reactive Oxygen Species / Q000494:pharmacology; D012480:Salmonella Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D019779:Salmonella enterica / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D017382:Reactive Oxygen Species