NAME: Escherichia coli, enterotoxigenic
CHARACTERISTICS: Enterotoxigenic Escherichia coli (ETEC) are in the family Enterobacteriaceae Footnote 3. The bacteria are gram negative, rod shaped, non-spore forming, motile with peritrichous flagella or nonmotile, and grow on MacConkey agar (colonies are 2 to 3 mm in diameter and red or colorless) Footnote 4. They are able to grow under aerobic and anaerobic conditions Footnote 1, and produce two types of enterotoxin: heat-labile (LT) (oligomeric) and heat-stable (ST) (monomeric) Footnote 2, Footnote 3.
PATHOGENICITY/TOXICITY: Patients with ETEC enteritis usually have an abrupt onset of watery diarrhea that does not contain blood, pus, or mucus (nondysenteric) Footnote 1. The diarrhea is usually mild to moderate in severity, but some patients may have severe fluid loss Footnote 1. Low-grade fever, nausea, and abdominal pain may also be present Footnote 5. Dehydration may become severe or life threatening in neonates and children, necessitating aggressive fluid and electrolyte replacement Footnote 2. A self-limited course, with resolution in 2-5 days, is most common in adult travelers who acquire the disease Footnote 1, though some strains of the organism may produce a disease lasting much longer, with a median duration of illness of 7 days Footnote 6. There are an estimated 800,000 deaths each year due to ETEC Footnote 7.
EPIDEMIOLOGY: Human diarrhea caused by ETEC is the most common disease caused by pathogenic E. coli strains Footnote 7. It is estimated that there are more than 650 million cases of ETEC infection each year Footnote 7. ETEC infections are most common in developing countries that lack appropriate sanitation and drinking-water treatment facilities Footnote 1, Footnote 2 but are now considered a re-emerging food- and water-borne disease in developed nations as well. In developing nations disease occurs at any time of the year, but incidence peaks in the warm, wet seasons that favor environmental bacterial replication Footnote 1. ETEC is a disease of young children in developing nations Footnote 2. The percentage of ETEC in children with diarrhoea varies from 10-30% Footnote 8. In endemic areas, 20–40% of diarrhea cases are due to ETEC Footnote 8. Several studies suggest that 20–60% of travellers from developed countries experience diarrhoea when visiting the areas where ETEC infection is endemic Footnote 8. Furthermore, several outbreaks have occurred on cruise ships, which appear to constitute a fairly frequent setting for disease caused by this organism Footnote 9. Outbreaks of ETEC caused by endemic strains, rather than association with travel, have occurred in the U.S.Footnote 10-Footnote 12 and Denmark Footnote 13, Footnote 14. As with travel-associated diarrhea, disease caused by ETEC in developed nations tends to strike older children and adults.
HOST RANGE:Humans (principally neonates and travelers from non-endemic areas) Footnote 7 and animals (production animals and postweaning diarrhea in swine) Footnote 7. ETEC have been strongly associated with cattle Footnote 15, though the role of cattle as a source of strains for human infection is currently unclear.
INFECTIOUS DOSE: The infectious dose of ETEC in adult is estimated to be at least 108 organisms, but the young, the elderly and the infirm may be susceptible to lower numbers Footnote 16.
MODE OF TRANSMISSION: ETEC are spread primarily by the fecal-oral route and are most common in developing countries that lack appropriate sanitation and drinking-water treatment facilities Footnote 17. The most important mode of transmission is contaminated, improperly treated drinking water Footnote 1, Footnote 2. Fruits and vegetables that are washed with contaminated water and not cooked also serve as vehicles of transmission Footnote 1, Footnote 2. Person-to-person spread is uncommon Footnote 17.
INCUBATION PERIOD: The incubation period is short at between 14 and 30 hours Footnote 5.
ZOONOSIS: None reported Footnote 19.
DRUG SUSCEPTIBILITY/RESISTANCE: Susceptible to carbapenem, fosfomycin-trometanol, nitrofurantoin, and bovine apo-lactoferrin Footnote 2, Footnote 20. E. coli can be resistant to chloramphenicol, β lactams, nalidixic acid, ampicillin, and ciprofloxacin Footnote 2. Fluoroquinolones such as ciprofloxacin enhance toxin production.
SUSCEPTIBILITY TO DISINFECTANTS: Susceptible to a combination of 2,2-dibromo-2-cyanoacetamide (DBA) with sodium iodide (20:80 parts), iodine, 2 % glutaraldehyde, quaternary ammonium (20°C, 0.5 min), hypochlorite (0.525%, 20°C, 0.5 min), phenolic (20°C, 0.5 min), and ethyl alcohol (70%, 20°C, 0.5 min) Footnote 21-Footnote 23.
SURVIVAL OUTSIDE HOST: E. coli can survive for 1.5 hours to 16 months on dry inanimate surfaces Footnote 26.
SURVEILLANCE: Monitor for symptoms. Stool culture is a common method used to identify E. coli Footnote 27. ETEC can be detected using non-radioactively labeled oligonucleotides DNA probes and PCR targeted against the LT and ST genes Footnote 1, Footnote 2. ELISA can also be used to detect LT and ST Footnote 1, Footnote 2.
Note: All diagnostic methods are not necessarily available in all countries.
FIRST AID TREATMENT: Treatment with trimethoprim/sulfamethoxazole (TMP-SMX) or quinolones reduces the duration of diarrhea Footnote 18. Treatment of fluid and electrolyte loss is usually achieved through oral rehydration Footnote 1, Footnote 19. The use of the World Health Organization Oral Rehydration Salts (ORS) solution has been recommended Footnote 1. Intravenous rehydration may be necessary for infants, individuals with excessive vomiting, or those with severe dehydration Footnote 1. Bismuth subsalicylate may decrease the amount of diarrhea and the duration of disease Footnote 1. Antimicrobial therapy is generally not indicated, because of the self-limited nature of this disease Footnote 1.
IMMUNIZATION: There are currently no vaccines approved for human use against the diarrheagenic E coli Footnote 1.
PROPHYLAXIS: TMP-SMX is recommended for a short term (< 2 weeks) for those at a high risk of disease Footnote 18. Bismuth subsalicylate provides some prophylactic benefit, but should not be used as a substitute for other preventive measures Footnote 1.
LABORATORY ACQUIRED INFECTIONS: 12 cases of laboratory acquired infections with E. coli have been reported, the majority have been caused by enterohemorrhagic E.coli (EHEC) Footnote 28.
PRIMARY HAZARD: Ingestion Footnote 28.
SPECIAL HAZARD: None.
RISK GROUP CLASSIFICATION: Risk Group 2 Footnote 29.
CONTAINMENT REQUIREMENTS: Containment Level 2 facilities, equipment, and operational practices for work involving infectious or potentially infectious materials, animals, or cultures Footnote 30.
PROTECTIVE CLOTHING: Lab coat. Gloves when direct skin contact with infected materials or animals is unavoidable Footnote 30. Eye protection must be used where there is a known or potential risk of exposure to splashes.
OTHER PRECAUTIONS: All procedures that may produce aerosols, or involve high concentrations or large volumes should be conducted in a biological safety cabinet (BSC) Footnote 30. The use of needles, syringes, and other sharp objects should be strictly limited. Additional precautions should be considered with work involving animals or large scale activities.
SPILLS: Allow aerosols to settle and, wearing protective clothing, gently cover spill with paper towels and apply an appropriate disinfectant, starting at the perimeter and working towards the centre. Allow sufficient contact time before clean up Footnote 30.
DISPOSAL: Decontaminate all wastes that contain or have come in contact with the infectious organism by autoclave, chemical disinfection, gamma irradiation, or incineration before disposing Footnote 30.
STORAGE: The infectious agent should be stored in leak-proof containers that are appropriately labeled Footnote 30.
REGULATORY INFORMATION: The import, transport, and use of pathogens in Canada is regulated under many regulatory bodies, including the Public Health Agency of Canada, Health Canada, Canadian Food Inspection Agency, Environment Canada, and Transport Canada. Users are responsible for ensuring they are compliant with all relevant acts, regulations, guidelines, and standards.
UPDATED: December 2011
PREPARED BY: Pathogen Regulation Directorate, Public Health Agency of Canada
Although the information, opinions and recommendations contained in this Pathogen Safety Data Sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.
Public Health Agency of Canada, 2011