A virulent strain of Salmonella enterica serovar London isolated in infants with enteritis traced by active surveillance and molecular epidemiological study.
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.
Kim
Shukho
S
Department of Microbiology, National Institute of Health, 5 Nokbun-dong, Eunpyung-gu, Seoul, Korea.
Lee
Bok Kwon
BK
Kang
Yeon Ho
YH
Nam
Hee Jung
HJ
Lim
Ok Young
OY
Seok
Won Seok
WS
Park
Jae Ku
JK
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
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D017382:Reactive Oxygen Species