J Korean Med Sci.  2003 Jun;18(3):325-330. 10.3346/jkms.2003.18.3.325.

A Virulent Strain of Salmonella enterica Serovar London Isolated in Infants with Enteritis Traced by Active Surveillance and Molecular Epidemiological Study

• Kim S
• Kang YH
• Nam HJ
• Lim OY
• Seok WS
• Park JK
• Lee BK

• KMID: 2157645
• DOI: http://doi.org/10.3346/jkms.2003.18.3.325

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.

Keyword

Salmonella enterica; Salmonelloses; Infants; Epidemiology; Sentinel Surveillance; Elec-trophoresis, gel, Pulsed-Field; Biological Assay

MeSH Terms

Adult
Anti-Bacterial Agents/therapeutic use
DNA, Bacterial/analysis
Diarrhea/epidemiology/microbiology
Disease Outbreaks
Enteritis/*epidemiology/microbiology
Feces/microbiology
Human
In Vitro
Infant
Microbial Sensitivity Tests
Middle Aged
Reactive Oxygen Species/pharmacology
Salmonella Infections/drug therapy/*epidemiology/microbiology
Salmonella enterica/genetics/*isolation & purification/pathogenicity
Virulence