Molecular Epidemiological Analysis of Five Outbreaks Associated withSalmonella entericaSerovar Enteritidis Between 2008 and 2010 on Jeju Island, Republic of Korea

Abstract

With the increasing incidence of Salmonella enterica serovar Enteritidis (SE) infections, five SE foodborne outbreaks were identified between 2008 and 2010 on Jeju Island, Republic of Korea. In this study, the genetic relatedness of isolates recovered from the five outbreaks was investigated to identify the source of foodborne SE infections. In total, 57 SE isolates from five outbreaks (17 isolates, 5 isolates, 18 isolates, 8 isolates, and 9 isolates, respectively) were used for antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE), and multiple-locus variable-number tandem repeat analysis (MLVA). SE isolates from 2008 and 2009 were resistant to nalidixic acid, whereas SE isolates from 2010 were resistant to five antibiotics. Of the five outbreaks, outbreaks A, B, and D had identical PFGE-XbaI and PFGE-BlnI patterns, SEGX01.003 and SEGA26.001, respectively. Outbreak C had patterns SEGX01.011 and SEGA26.005, and outbreak E had patterns SEGX01.007 and SEGA26.007. However, MLVA profiles further distinguished the SE isolates from each outbreak into patterns SEGM.014 (outbreak A), SEGM.012 (outbreak B), SEGM.008 (outbreak C), SEGM.016 (outbreak D), and SEGM.015 (outbreak E). Among these five outbreaks, three outbreaks were presumed to be caused by the clonal SE isolates depending on PFGE pattern, but the MLVA results elucidated that these were caused by different SE isolates from the different origins. Therefore, for the epidemiological investigation or surveillance of SE foodborne diseases, both PFGE and MLVA should be used together.

Genetically Similar Isolates ofSalmonella entericaSerotype Enteritidis Persistent in China for a Long‐Term Period

“…Similar PFGE patterns against reference strain S . Braenderup (H9812) were also reported in several outbreaks in Korea and Japan (Kim and others ; Tokuzaki and Takahashi ) (Figure ). In Korea from 2008 to 2010, 3 outbreaks have been identified to be associated with strains of the similar PFGE pattern and MLVA (array: SE1‐SE2‐SE3‐SE5‐SE6‐SE8‐SE9) that is 5‐4‐3‐11‐10‐1‐3 and very similar to our MLVA results (4‐4‐3‐11‐10‐1‐3).…”

Molecular epidemiological characteristics of Salmonella enterica serovars Enteritidis, Typhimurium and Livingstone strains isolated in a Tunisian university hospital

“…Salmonella enterica is the leading cause of foodborne disease and it is responsible for nosocomial outbreaks worldwide . Enteritidis and Typhimurium are the two common serovars described.…”

The evaluation and application of multilocus variable number tandem repeat analysis (MLVA) for the molecular epidemiological study of Salmonella enterica subsp. enterica serovar Enteritidis infection

“…The Simpson’s and Shannon’s diversity indices were higher for PFGE than for MLVA. However, the MLVA typing method showed much higher discriminatory power than PFGE in studies from other countries [ 5 , 15 , 27 , 28 ]. Although the two indices were higher for PFGE than for MLVA, the values were not significantly different.…”

“…MLVA is rapid and highly reproducible, and the results can be easy to be interpreted and standardized among laboratories. Bacteria that have been typed by MLVA include S. Typhimurium [ 12 , 13 ], S. Enteritidis [ 14 , 15 ], E. coli O157:H7 [ 16 , 17 ], and Vibrio parahaemolyticus [ 18 ]. In recent years, MLVA has been proposed as a supplement to PFGE for subtyping S. Enteritidis in many countries.…”