A large, multiple-restaurant outbreak of infection with Shigella flexneri serotype 2a traced to tomatoes.
BACKGROUND
Foodborne outbreaks of Shigella infection are uncommon and tomatoes are an unusual vehicle. We describe a large, multiple-restaurant outbreak of Shigella flexneri serotype 2a infection that was associated with tomatoes.


METHODS
We conducted nationwide surveillance and a case-control study, collected fecal specimens for culture, and measured the survival of the outbreak strain of S. flexneri in tomatoes.


RESULTS
We interviewed 306 of 886 ill restaurant patrons and 167 control subjects. Matched univariate analysis showed that several food items were associated with illness, but only tomatoes remained significant in multivariate models. Illness peaked at each restaurant within 24 h after the arrival of hand-sorted bruised and overripe tomatoes from a new distributor; all patient isolates that were tested were indistinguishable by PFGE. Sliced tomatoes from the distributor were inoculated with the outbreak strain, and viable S. flexneri were recovered for 72 h.


CONCLUSIONS
To prevent such outbreaks, persons with shigellosis should be excluded from handling food at all points along the distribution chain.
Reller
Megan E
ME
Foodborne and Diarrheal Diseases Branch, Division of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA. megan.reller@tch.harvard.edu
Nelson
Jennifer M
JM
Mølbak
Kåre
K
Ackman
David M
DM
Schoonmaker-Bopp
Dianna J
DJ
Root
Timothy P
TP
Mintz
Eric D
ED
D000328:Adult; D016022:Case-Control Studies; D004196:Disease Outbreaks; D004405:Dysentery, Bacillary / Q000453:epidemiology* / Q000382:microbiology*; D005260:Female; D005516:Food Microbiology; D006801:Humans; D018551:Solanum lycopersicum / Q000382:microbiology*; D008297:Male; D008875:Middle Aged; D009518:New York / Q000453:epidemiology; D011159:Population Surveillance; D012147:Restaurants; D012763:Shigella flexneri / Q000145:classification / Q000302:isolation & purification*