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Non-pathogenic Escherichia coli Strains Biological Agent Reference Sheet (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-1 BSL-1 ABSL-1

Agent Characteristics 

Risk Group:  RG-1 not associated with disease in healthy human adults.

Agent Type:  Bacteria 

Description: Gram-negative rod; motile, aerobic; does not contain toxin genes (stx1/stx2), often derivatives of either B or K strains. Examples 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.

Host Range: Humans, mammals, fish, and reptiles.                Host Shedding: Feces                            

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

Infectious Dose: N/A                                                         Incubation Period: N/A

Health Hazards

Signs and symptoms of infection may include:

  • Attenuated strains of E. coli may pose a risk to immunocompromised individuals.

Immunizations: None available                                            Prophylaxis*: Not applicable

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

Agent Viability 

Survival Outside Host Disinfection

Undetectable after 6 weeks in fecal material; undetectable after 2 months in soil.

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 (innoculum of 108 cfu/mL became undetectable after 9 days).

1:10 Bleach Dilution 

For more guidance on disinfection see: disinfectant selection.

Laboratory Hazards 

  • 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 with wild-type infectious E. coli since 1981.

Laboratory Handling Guidelines 

Laboratory Biosafety Level (BSL): BSL-1


Lab Engineering Controls Personal Protective Equipment
  • Eye Protection
  • Single gloves
  • Snap-front lab coat with cinch cuffs

Waste Management: Plates may be autoclaved in a clear (non-biohazard) autoclave bag and taken to the dumpster. Be cognizant of genetically modified strains which may need to go to Regulated Medical Waste.

Shipping Guidance: Refer to EHS Biological Materials Shipping 

Animal Vivarium Guidance

Animal Housing Biosafety Level (ABSL): ABSL-1

Animal Biosecurity: No concerns       

Perform Inoculations: On a Benchtop

Change Cages: On a Benchtop

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.

Small Spills: Notify others working in the lab. Evacuate area and allow 30 minutes for aerosols to settle. Don appropriate PPE. Cover area of the spill with paper towels and apply disinfectant, working from the perimeter toward the center. Allow 30 minutes of contact time before disposal and cleanup of spill materials. See: spill cleanup.

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. 

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