Published Date: 2012-01-17 12:53:37
Subject: PRO/AH/EDR> E. coli EHEC - USA: (MI) food handler
Archive Number: 20120117.1013132
E. COLI EHEC - USA: (MICHIGAN) FOOD HANDLER
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Thu 12 Jan 2012
Source: Western Upper Peninsula Health Department [edited]
Western Upper Peninsula [Michigan] Health Department is investigating a cluster of cases of _Escherichia coli_ O157:H7 infection who became ill over the Christmas holidays. Initially 3 local and 2 non-local cases were identified. Investigation has led to the identification of 2 additional cases. 4 of the cases were hospitalized; no deaths have occurred. The health department has determined that the likely source of the outbreak was an ill food handler at The Ambassador, a Houghton restaurant. The restaurant owner and his staff have been working cooperatively with the health department's environmental health division during the investigation. The restaurant remains open for business and there is no anticipated ongoing risk of illness due to this outbreak.
"Such an investigation is a routine part of health department operations," said Dr Teresa Frankovich, MD. "The cases came to light earlier in January 2012 and health department staff have been conducting interviews with the ill individuals to look for exposures they might have in common. All of the cases have now been linked through the restaurant."
According to Dr Frankovich, "Occasional, single cases of _E. coli_ diarrhea occur sporadically, but it is unusual to have a cluster of cases at the same time. Public health investigates clusters of disease or illness to make sure that there is no ongoing risk of illness and to make sure prevention efforts are in place."
One of the major sources of _E. coli_ contamination is ground beef; however, other sources include consumption of unpasteurized milk and juice, sprouts, lettuce, and salami, and contact with cattle. This organism is easily transmitted from person to person. The best prevention against foodborne illness is to wash hands before preparing food and avoid handling food when ill, make sure that food preparation surfaces are clean, cook meats to safe temperatures, wash produce before eating, and drink only pasteurized dairy and cider products.
[To conform to the current nomenclature of the pathotypes of _E. coli_ causing intestinal disease, this moderator will now use EHEC, enterohemorrhagic _E. coli_, to refer to both the O157 and the non-O157 serotypes. As a reminder:
Other _E. coli_ serogroups that have been associated with the EHEC pathotype include motile ones such as O26:H11 and O104:H21 and non-motile ones such as O111:NM (or H-). Such non-O157 isolates can be obtained from sheep and cattle and, although they cause as many as 30 per cent of outbreaks of EHEC (1), appear to be somewhat less (or at least more variably) virulent in a variety of in vivo and in vitro assays (2-4). In analyzing the genetic and phenotypic profiles of non-O157 groups, it has been found that they belong to their own lineages and have unique profiles of virulence traits different from O157 (5). The serogroups appearing to be most prominent are O26, O111, O128, and O103 (6).
If a laboratory is using sorbitol-MacConkey (sMAC) plates to identify EHEC by virtue of O157's inability to ferment sorbitol, the non-O157 strains will be missed. In a 3-year pediatric study from the University of Washington, USA (7), 1851 stool samples were processed for sorbitol fermentation as well as toxin production by EIA (enzyme immunoassay), and 28 strains of O157 were found along with O103 (4 strains), O118 (2 strains), O111 (2 strains), and 3 other strains. Clinically, the O157 infections had a higher frequency of bloody stools, fecal leukocytes, and abdominal pain with shorter symptom duration. 5 (18 per cent) of O157 infections developed hemolytic-uremic syndrome; none of the non-O157 strains did. Since toxin assay did not identify all O157 strains found on sMAC plates, the investigators did not advocate performing toxin assay alone. Non-O157 can produce hemolytic-uremic syndrome, as demonstrated by a cluster of O121 cases associated with a lake in Connecticut, USA (8).
Since toxin assays are not uniformly performed in many areas, and most cases do not produce HUS (hemolytic uremic syndrome), it is likely that cases due to non-O157 strains are being missed. How frequent this phenomenon will become over time is unclear. Because of the higher risk of morbidity and mortality in VTEC infections treated with antimicrobials (9), antimicrobials should not be used for known acute cases.
1. Hussain HS, Omaye ST. Introduction to the food safety concerns of verotoxin-producing _Escherichia coli_. Exp Biol Med 2003; 228(4): 331-2; available at http://ebm.rsmjournals.com/cgi/content/full/228/4/331.
2. Blanco J, Blanco M, Blanco JE, et al. Verotoxin-producing _Escherichia coli_ in Spain: prevalence, serotypes, and virulence genes of O157:H7 and non-O157 VTEC in ruminants, raw beef products, and humans. Exp Biol Med 2003; 228: 345-51; available at http://ebm.rsmjournals.com/cgi/content/full/228/4/345.
3. Law D, Kelly J. Use of heme and hemoglobin by _Escherichia coli_ O157 and other Shiga-toxin-producing _E. coli_ serogroups. Infect Immun 1995; 63(20): 700-2; available at http://iai.asm.org/cgi/reprint/63/2/700.pdf.
4. Tzipori S, Wachsmuth KI, Smithers J, Jackson C. Studies in gnotobiotic piglets on non-O157:H7 _Escherichia coli_ serotypes isolated from patients with hemorrhagic colitis. Gastroenterology 1988; 94(3): 590-7; abstract available at http://www.ncbi.nlm.nih.gov/pubmed/3276573.
5. Schmidt H, Geitz C, Tarr PI, et al: Non-O157:H7 pathogenic Shiga-toxin producing _Escherichia coli_: phenotypic and genetic profiling of virulence traits and evidence for clonality. J Infect Dis 1999; 179(1): 115-23; available at http://www.journals.uchicago.edu/doi/full/10.1086/314537.
6. Bettelheim KA: Role of non-O157 VTEC. Symp Ser Soc Appl Microbiol 2000; (29): 38S-50S; abstract available at http://www.ncbi.nlm.nih.gov/pubmed/10880178.
7. Klein EJ, Stapp JR, Calusen CR, et al: Shiga toxin-producing _Escherichia coli_ in children with diarrhea: a prospective point-of-care study. J Pediatr 2002; 141(2): 172-7; available at http://www.ncbi.nlm.nih.gov/pubmed/12183710.
8. McCarthy TA, Barrett NL, Hadler JL, et al: Hemolytic-uremic syndrome and _Escherichia coli_ O121 at a lake in Connecticut, 1999. Pediatrics 2001; 108(4): E59; available at http://pediatrics.aappublications.org/cgi/content/full/108/4/e59.
9. Iijima K, Kamioka I, Nozu K: Management of diarrhea-associated hemolytic uremic syndrome in children. Clin Exp Nephrol 2008; 12(1): 16-9; abstract available at http://www.springerlink.com/content/02284n422l6700l7/. - Mod.LL
The city of Houghton can be located on the HealthMap/ProMED-mail interactive map at http://healthmap.org/r/1EPn. - Sr.Tech.Ed.MJ]