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Pathogenic Escherichia coli Strains Biological Agent Reference Sheets (BARS)

Updated October 2, 2023
Disclaimer: Risk group, biosafety level, and all other precautions noted here are subject to change after a risk assessment by EHS.


Agent Type Risk Group Biosafety Level Animal Housing Biosafety Level
Bacteria  RG-2 BSL-2 ABSL-2

Agent Characteristics 

Risk Group: RG-2 associated with human disease, rarely serious; preventive or therapeutic interventions often available.

Agent Type: Bacterium 

Description: Gram negative rod; motile, aerobic; produces Vero /Shiga toxins (VT/STx), 2 types, VT1/Stx1 and VT2/Stx2. Use serotyping to determine somatic and flagellar antigens. Genotyping PCR will identify Toxin types. Use antibiotic susceptibility testing to rule out Multi Drug Resistant (MDR) strains.

Host Range: Humans, Mammals (agricultural and wild)               Host Shedding: Blood, Feces, Urine

Route of Exposure to Humans: Direct Contact, Mucous Membranes, Contaminated Items, Ingestion, Percutaneous

Infectious Dose: Human infection can result from as low as 10 organisms by ingestion                              

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

Health Hazards

Signs and symptoms of infection may include:

  • Gastrointestinal symptoms (i.e. loss of appetite, nausea, vomiting, diarrhea)

Immunizations: None available                               Prophylaxis*: Available

*Formal medical advice is obtained during medical consultations with Cornell Health or primary healthcare provider as needed.

Agent Viability 

Survival Outside Host Disinfection

Survives well in contaminated feces and soil, with only a small reduction in organism number over 2 months. Survives well in foods: up to 50 min in butter; 10 days in cream; survives well in hamburger meat; does not survive long in slurry systems (inoculum of 108 cfu/mL became undetectable after 9 days) 

1:10 Bleach Dilution 

Moist heat at 121°C for at least 1 hour; dry heat at 160-170°C for at least 1 hour

For more guidance on disinfection see: disinfectant selection.

Laboratory Hazards 

  • High energy-creating activities (centrifugation, sonication, high-pressure systems, vortexing, tube cap popping)
  • Handling of sharps (needles, scalpels, microtome blades, broken glass, etc.)
  • Splash/droplet-creating activities (shaking incubators, liquid culturing, mechanical pipetting)
  • Equipment contamination
  • Exposed skin/uncovered wounds

Laboratory Acquired Infection (LAI) History: Twelve reported cases of laboratory infections of E. coli since 1981.

Laboratory Handling Guidelines 

Laboratory Biosafety Level (BSL): BSL-2

Attenuated Strain Alternatives: Due to the extremely low infectious dose of this pathogen, attenuated strains should be worked with where possible. Recommended alternative strains include: E. coli K12, E. coli 25922, E. coli Nissle, E. coli Castellani and Chalmers ATCC 700728, and other E. coli strains approved by EHS Biosafety pending documented absence of shiga-toxin producing genes.

Training Lab Engineering Controls Personal Protective Equipment
  • Eye Protection
  • Single gloves
  • Additional gloves
  • Snap-front lab coat with cinch cuffs
  • Disposable outer sleeves

Waste Management: Regulated Medical Waste (RMW)

Shipping Guidance: Refer to EHS Biological Materials Shipping 

Animal Vivarium Guidance

Animal Housing Biosafety Level (ABSL): ABSL-2

Animal Biosecurity: Experimental animals are housed separately         

Perform Inoculations: In a Biosafety Cabinet

Change Cages: In a Biosafety Cabinet

Exposure and Spill Procedures 

Mucous Membranes: Flush eyes, mouth, or nose for 15 minutes at an eyewash station. See: responding to exposures.

Other Exposures: Wash with soap and water for 15 minutes (open wounds, sores, etc.) or a minimum of 20 seconds for areas with intact skin. See: responding to exposures.

Large Spills: Request assistance from the EHS Spill Team by calling CUPD dispatch. Call 911 from a campus phone or 607-255-1111 from a mobile phone.

Incident Reporting: Immediately report the incident to supervisor and complete the EHS online injury/illness report as soon as possible.

Medical Follow-Up:

  • For students, seek medical attention at Cornell Health or local primary care provider. Call Cornell Health at 607-255-5155 (24-hour phone consultation line) or a local urgent care. 
  • For faculty and staff, seek medical evaluation with a local primary care provider or urgent care. Cornell Health does not see employees for post-exposure care. 
  • Emergencies: Call 911 from a campus phone or 607-255-1111 from a mobile phone. 
Cornell EHS would like to thank Emory University for the use of their Biological Agent Reference Sheet (BARS) format and some content. 

More Information


  1. Health Canada Pathogen Safety Data Sheet

  2. Harding, A. L., & Byers, K. B. (2006). Epidemiology of Laboratory-associated infections. In Fleming, D and Hunt, D. (Ed.), Biological Safety: principles and practices (4th ed., pp. 53-77). Washington, DC, USA: ASM press.