Surveillance of Shiga toxin-producing Escherichia coli in beef with effective procedures, independent of serotype.
To detect various serotypes of Shiga toxin-producing Escherichia coli (STEC) in food, methods independent of serotyping are needed. We established procedures to isolate STEC using a rapid and sensitive loop-mediated isothermal amplification (LAMP) assay targeting the Shiga toxin (ST) gene and a method of plating LAMP assay positive dilutions onto media for the selection of E. coli. After incubation, suspensions of a colony or some colonies were tested in the LAMP assay. Positive suspensions were diluted and plated onto selective media. The procedure was repeated. Finally, LAMP positive colonies were confirmed as STEC and serotype. As a result of surveillance in beef in 2005-2007, 11 of 720 samples (1.5%) tested positive for the ST gene by LAMP assay. Serotype O8, O128, and O-untypeable STEC were isolated from the samples by the newly established procedure. It was demonstrated that the procedure was effective for detecting STEC independent of serotype.
Hara-Kudo
Yukiko
Y
Division of Microbiology, National Institute of Health Sciences, Tokyo, Japan. ykudo@nihs.go.jp
Niizuma
Jun
J
Goto
Ikuo
I
Iizuka
Shinji
S
Kaji
Yoshifumi
Y
Kamakura
Kazumasa
K
Suzuki
Sosuke
S
Takatori
Kosuke
K
D000818:Animals; D001315:Australia / Q000453:epidemiology; D002417:Cattle; D015169:Colony Count, Microbial; D003470:Culture Media; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D006801:Humans; D018189:Immunomagnetic Separation; D008460:Meat / Q000382:microbiology*; D015995:Prevalence; D012680:Sensitivity and Specificity; D012703:Serotyping; D022603:Shiga Toxins / Q000096:biosynthesis / Q000235:genetics*; D054323:Shiga-Toxigenic Escherichia coli / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D014481:United States / Q000453:epidemiology
D003470:Culture Media; D022603:Shiga Toxins