German outbreak of Escherichia coli O104:H4 associated with sprouts.
BACKGROUND
A large outbreak of the hemolytic-uremic syndrome caused by Shiga-toxin-producing Escherichia coli O104:H4 occurred in Germany in May 2011. The source of infection was undetermined.


METHODS
We conducted a matched case-control study and a recipe-based restaurant cohort study, along with environmental, trace-back, and trace-forward investigations, to determine the source of infection.


RESULTS
The case-control study included 26 case subjects with the hemolytic-uremic syndrome and 81 control subjects. The outbreak of illness was associated with sprout consumption in univariable analysis (matched odds ratio, 5.8; 95% confidence interval [CI], 1.2 to 29) and with sprout and cucumber consumption in multivariable analysis. Among case subjects, 25% reported having eaten sprouts, and 88% reported having eaten cucumbers. The recipe-based study among 10 groups of visitors to restaurant K included 152 persons, among whom bloody diarrhea or diarrhea confirmed to be associated with Shiga-toxin-producing E. coli developed in 31 (20%). Visitors who were served sprouts were significantly more likely to become ill (relative risk, 14.2; 95% CI, 2.6 to ∞). Sprout consumption explained 100% of cases. Trace-back investigation of sprouts from the distributor that supplied restaurant K led to producer A. All 41 case clusters with known trading connections could be explained by producer A. The outbreak strain could not be identified on seeds from the implicated lot.


CONCLUSIONS
Our investigations identified sprouts as the most likely outbreak vehicle, underlining the need to take into account food items that may be overlooked during subjects' recall of consumption.
Department of Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany. buchholzu@rki.de
Udo
U
Buchholz
Helen
H
Bernard
Dirk
D
Werber
Merle M
MM
Böhmer
Cornelius
C
Remschmidt
Hendrik
H
Wilking
Yvonne
Y
Deleré
Matthias
M
an der Heiden
Cornelia
C
Adlhoch
Johannes
J
Dreesman
Joachim
J
Ehlers
Steen
S
Ethelberg
Mirko
M
Faber
Christina
C
Frank
Gerd
G
Fricke
Matthias
M
Greiner
Michael
M
Höhle
Sofie
S
Ivarsson
Uwe
U
Jark
Markus
M
Kirchner
Judith
J
Koch
Gérard
G
Krause
Petra
P
Luber
Bettina
B
Rosner
Klaus
K
Stark
Michael
M
Kühne
D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D016022:Case-Control Studies; D015331:Cohort Studies; D003132:Commerce; D004196:Disease Outbreaks; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000209:etiology; D007887:Fabaceae / Q000382:microbiology*; D005260:Female; D005516:Food Microbiology; D005858:Germany / Q000453:epidemiology; D006463:Hemolytic-Uremic Syndrome / Q000453:epidemiology* / Q000382:microbiology; D006801:Humans; D027806:Lens Plant / Q000382:microbiology; D008297:Male; D000455:Medicago sativa / Q000382:microbiology; D008875:Middle Aged; D018520:Plant Shoots / Q000382:microbiology*; D012147:Restaurants; D054323:Shiga-Toxigenic Escherichia coli; D029910:Trigonella / Q000382:microbiology