Enterohemorrhagic or Shiga-toxin E. coli

Boston University
Research Occupational Health Program (ROHP)
617-358-7647

Agent

E. coli O157:H7 Gram negative rod; motile, aerobic; 63% produce Vero/Shiga toxins (VT/STx), 2 types, VT1/Stx1 and VT2/Stx2 (STEC); serotyping to determine somatic and flagellar antigens

Disease/Infection

Hemorrhagic colitis, hemolytic uremic syndrome

Pathogenicity

Can cause moderate to severe infection marked by hemorrhagic colitis, which can lead to dehydration, shock and death. Some patients may develop HUS, marked by renal failure, confusion, thrombocytopenia and micro hemolytic anemia, complicating 6 to 9 percent of infections.

• Special Populations at Risk:
  Higher death rates occur in elderly and young; can cause thrombocytopenic purpura (TTP) in elderly.

Biosafety Information

Risk Group/BSL
Risk group 2
Biosafety level 2

Modes of Transmission

Host Range/Reservoir
Host range: Humans; animals (piglets, calves and cattle)/Reservoir: Infected persons, animals (sheep, goats, pigs, poultry, calves, cattle)

Symptoms
Symptoms often begin slowly with mild belly pain or non-bloody diarrhea that worsens over several days. Hemorrhagic colitis, intestinal disease, occurs accompanied by initially watery, followed by bloody diarrhea; low grade fever; last about 8 days; 6-9% of hemorrhagic colitis victims may develop hemolytic uremic syndrome (HUS); affects all ages, higher death rates occur in elderly and young; can cause thrombocytopenic purpura (TTP) in elderly.

HUS, if it occurs, develops an average 7 days after the first symptoms, when the diarrhea is improving.

Incubation Period
2-8 days (median of 3-4 days)

Viability
Susceptible to many disinfectants – 1% sodium hypochlorite, 70% ethanol, phenolics, glutaraldehyde, iodines, formaldehyde

Survival Outside Host
Survives well in contaminated feces and soil, only small reduction in organism number over 2 months. Does not survive long in slurry systems (inoculum of 10⁸ cfu/mL became undetectable after 9 days)

Information for Lab Workers

Laboratory PPE

Laboratory coat, gloves, eye protection must be work when in contact with infectious materials. Face shield can be recommended based on risk assessment.

Containment

Biosafety level 2 practices, containment equipment and facilities for activities involving cultures and infected clinical materials.

In Case of Exposure/Disease

• For injuries in the lab which are major medical emergencies (heart attacks, seizures, etc…):
  • Medical Campus: call or have a coworker call the Control Center at 617-414–4144.
  • Charles River Campus: call or have a coworker call campus security at 617-353-2121.
    You will be referred to or transported to the appropriate health care location by the emergency response team.
• For lab exposures (needle sticks, bite, cut, scratch, splash, etc…) involving animals or infectious agents, or for unexplained symptoms or illness call the ROHP 24/7 hour number (1-617-358-ROHP (7647); or, 8-ROHP (7647) if calling from an on-campus location) to be connected with the BU Research Occupational Health Program (ROHP) medical officer. ROHP will refer you to the appropriate health care location.
• Under any of these scenarios, always inform the physician of your work in the laboratory and the agent(s) that you work with.
• Provide the wallet-size agent ID card to the physician.

Vaccination

There are no vaccines against Escherichia coli (EHEC 0157:H7)

Information for First Responders/Medical Personnel

Public Health Issues

A LAI from E. coli O157:H7 is reportable to the Boston Public Health Commission. Health care providers should immediately report to local board of health (BPHC) where the diagnosis was made.

Diagnosis/Surveillance

To diagnose illness caused by E. coli infection, a sample of your stool will be sent to a laboratory to test for the presence of E. coli bacteria. The bacteria may be cultured to confirm the diagnosis and identify specific toxins, such as those produced by E. coli O157:H7. Newer techniques make use of DNA probes to identify Shiga toxins in fecal samples.

First Aid/Post Exposure Prophylaxis

Perform one of the following actions:

Treatment

Non-specific supportive therapy, including hydration, is important. Antibiotics should not be used to treat this infection. There is no evidence that treatment with antibiotics is helpful, and taking antibiotics may increase the risk of Hemolytic Uremic Syndrome (HUS). Antidiarrheal agents like Imodium® may also increase that risk.

References

Biosafety in Microbiological and Biomedical Laboratories; Deborah E. Wilson, DrPH, CBSP Director Division of Occupational Health and Safety National Institutes of Health Bethesda, Maryland L. Casey Chosewood, M.D. Director Office of Health and Safety Centers for Disease Control and Prevention Atlanta, Georgia; US Government Printing Office, Washington DC. 5^th Edition; 2009

Control of Communicable Diseases Manual. David L. Heymann. Washington DC, USA: American Public Health Association Press, 19th edition; 2008

CDC, National Center for Zoonotic, Vector- Borne, and Enteric disease: http://www.cdc.gov/ecoli/index.html

Massachusetts Department of Public Health, Bureau of Communicable Disease Control, Guide to Surveillance, Reporting and Control: https://www.mass.gov/handbook/guide-to-surveillance-reporting-and-control 

105 CMR: Department of Public Health, 105 CMR 300.000: Reportable Diseases, Surveillance, and Isolation and   Quarantine Requirements: https://www.mass.gov/regulations/105-CMR-30000-reportable-diseases-surveillance-and-isolation-and-quarantine-requirements 

Revised: 10/30/2013