Enteroaggregative Escherichia coli associated with a foodborne outbreak of gastroenteritis.
This study investigated two foodborne outbreaks of gastroenteritis that occurred 10 days apart among individuals who had meals at the restaurant of a farm holiday resort. Mild gastrointestinal symptoms were reported and none of the patients needed hospitalization. Mean incubation times were 45 and 33 h, and the overall attack rates were 43.5 and 58.3%, respectively. Stool sample examination was negative for common enteric pathogens in both outbreaks. Specimens from 13 people involved in the second outbreak and 3 restaurant staff were examined for diarrhoeagenic Escherichia coli. An enteroaggregative E. coli (EAEC) strain of serotype O92:H33 was isolated from six participants and one member of staff. In particular, the EAEC strain was isolated from five of the six cases of diarrhoea examined. The strain showed an aggregative pattern of adherence to HEp-2 cells, did not produce a biofilm and possessed the virulence-related genes aat, aggR, aap and set1A, but not the astA gene. A retrospective cohort study indicated a pecorino cheese made with unpasteurized sheep milk as the possible source (P<0.001). Samples of the cheese had E. coli counts higher than 10(6) c.f.u. g(-1), but the outbreak EAEC strain was not isolated. This report confirms that EAEC infections are probably underdiagnosed because of the limited availability of laboratories capable of identifying this group of pathogenic E. coli.
Scavia
Gaia
G
Dipartimento di Sanità Pubblica Veterinaria e Sicurezza Alimentare, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy.
Staffolani
Monica
M
Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche, Macerata, Italy.
Fisichella
Stefano
S
Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche, Macerata, Italy.
Striano
Gianluca
G
Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche, Macerata, Italy.
Colletta
Stefano
S
Azienda Sanitaria Unica Regionale, Civitanova Marche, Italy.
Ferri
Giovanni
G
Azienda Sanitaria Unica Regionale, Civitanova Marche, Italy.
Escher
Martina
M
Dipartimento di Sanità Pubblica Veterinaria e Sicurezza Alimentare, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy.
Minelli
Fabio
F
Dipartimento di Sanità Pubblica Veterinaria e Sicurezza Alimentare, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy.
Caprioli
Alfredo
A
Dipartimento di Sanità Pubblica Veterinaria e Sicurezza Alimentare, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy.
D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D002611:Cheese / Q000382:microbiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004196:Disease Outbreaks; D004926:Escherichia coli / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology*; D005243:Feces / Q000382:microbiology; D005516:Food Microbiology; D005517:Foodborne Diseases / Q000453:epidemiology / Q000382:microbiology*; D005759:Gastroenteritis / Q000453:epidemiology / Q000382:microbiology*; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008875:Middle Aged; D012189:Retrospective Studies; D012756:Sheep; D011795:Surveys and Questionnaires