Listeria Monocytogenes

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Gram positive, aerobic, mobile, intracellular coccobacilli that may form chains.

Growth Conditions

Growth at 4°C.

Health Hazards

Host Range

Mammals, fish, birds, crustaceans, and insects. Pregnant women, the elderly, immunocompromised, fetuses, and neonates are the most at risk for listeriosis.

Modes of Transmission

Ingestion of contaminated food, direct contact with contaminated soil, and transmission from the mother to fetus during birth. Infected mothers may shed for 7-10 days after delivery.

Signs and Symptoms

Symptoms of listeriosis include fever, muscle ache, nausea, and diarrhea may occur. Infection may spread to the nervous system causing meningitis. Endocarditis (inflammation of the heart's inner lining), septicemia, and disseminated granulomatous may occur in infected adults. Pregnant women may experience only a mild, flu-like illness. However, infections during pregnancy can lead to abortion, stillbirth, premature delivery, or infection of the newborn.

Infectious Dose


Incubation Period

From 3-70 days. Median incubation period is 21 days.

Medical Precautions/Treatment


None available.


None available.


Antibiotic therapy (penicillin or ampicillin alone or with aminoglycosides). Resistant to cephalosporin.


Monitor for symptoms. Test feces, CFS, or blood.

Emory Requirements

Report any exposures.

Laboratory Hazards

Laboratory Acquired Infections (LAIs)

There have only been 2 reported LAIs. Pregnant women should take special caution to avoid contact with infected material.


Cerebrospinal fluid, blood, placental/fetal tissue, genital track secretions, amniotic fluid, and infected animals. 

Supplemental References

Canadian MSDS

Pathogen Safety Data Sheets 


Biosafety in Microbiological and Biomedical Laboratories (BMBL) 


Listeria Information 



For all procedures involving clinical samples or bacterial culture.


For all procedures involving animals infected with L. monocytogenes.

Spill Procedures


Notify others working in the lab. Allow aerosols to settle. Don appropriate PPE. Cover area of the spill with paper towels and apply an EPA registered disinfectant, working from the perimeter towards the center. Allow 30 minutes of contact time before disposal and cleanup of spill materials. Decontaminate before disposal: steam sterilization, incineration, chemical disinfection


Contact Emory's Biosafety Officer (404-727-8863),
the EHSO Office (404-727-5922), or
The Spill Response Team (404-727-2888).

Exposure Procedures

Mucous membrane

Flush eyes, mouth or nose for 15 minutes at eyewash station.

Other Exposures

Wash area with soap and water for 15 minutes.


Immediately report incident to supervisor, complete an employee incident report in PeopleSoft.

Medical Followup 

7am-4pm (OIM): EUH (404-686-7941) EUHM (404-686-7106) WW (404-728-6431)

After Hours: OIM NP On Call 404-686-5500 PIC# 50464

Needle Stick (OIM): EUH (404-686-8587) EUHM (404-686-2352)

Yerkes: Maureen Thompson Office (404-727-8012) Cell (404-275-0963)



Susceptible to 1% sodium hypochlorite, 70% ethanol, and glutaraldehyde


Inactivated by moist heat (15 minutes at 121°C), dry heat (1 hour at 160-170°C), and short wave UV and gamma irradiation.

Survival Outside Host

Able to survive outside of hosts (water, soil, food, feces). Capable of growing at low temperatures(-4 to -0.1°C)

Personal Protective Equipment (PPE)

Minimum PPE Requirements

At minimum, personnel are required to don gloves, closed toed shoes, lab coat, and appropriate face and eye protection prior to working with L. monocytogenes. Additional PPE may be required depending on lab specific SOPs.

Additional Precautions

None required