Salmonella Typhi

Characteristics

Morphology Family Enterobacteriaceae. S. enterica is a facultative anaerobe, Gram-negative, non-motile rod that is 0.7-1.5 by 2.0-5.0 µm in size. S. enterica serotype Typhi (Salmonella Typhi) causes typhoid fever.
Growth Conditions The most commonly used media selective for Salmonella are SS agar, bismuth sulfite agar, Hektoen enteric (HE) medium, brilliant green agar and xylose-lisine-deoxycholate (XLD) agar.

Health Hazards

Host
Humans are the only host for Salmonella Typhi. Domestic and wild animals host S. enterica non-typhoidal serotypes.

Modes of Transmission

Salmonella Typhi is transmitted by consumption of contaminated food or water, contact with infected feces, person-to-person contact, or direct contact with infected animals.

Signs and Symptoms

The most common symptoms include sustained fever, abdominal cramps, and headache. Occasionally, patients have a rash of flat rose-colored spots. Individuals may carry Salmonella Typhi after symptoms have disappeared, thus the illness may return or it may be passed on to other people.

Infectious Dose <103 rods of Salmonella Typhi
Incubation Period Usually 12 to 72 hours, but it can last for up to six weeks depending on the inoculation dose.

Medical Precautions/Treatment

Prophylaxis Clean water supplies, hand hygiene, sanitation, avoid eating raw eggs or unpasteurized milk.
Vaccines Two types of vaccines are available for Salmonella Typhi. Vaccination is recommended for laboratory workers who work with this microorganism.
Treatment Typhoid fever is treated with antibiotics. Individuals who do not receive treatment may continue to have fever for weeks or months, and as many as 20% may die for complications of the infection.
Surveillance

Monitor for symptoms. Laboratory confirmation is done via isolation from stool or blood and by molecular analysis to identify the serotype.

Emory Requirements Report all incidents. Provide information to the Biosafety Office regarding potential CDC and/or USDA permit.

Laboratory Hazards

Laboratory Acquired Infections (LAIs) Salmonella Typhi frequently causes LAIs. Lab-acquired infections with Salmonella Typhi present with symptoms of septicemia, headache, abdominal pain and fever.
Sources Ingestion is the most frequent route followed by parenteral inoculation. Transmission outside the laboratory has been reported. Aerosol transmission may be possible.

Supplemental References

Containment

BSL2/ABSL2

All work with Salmonella-infected samples or propagation of the bacteria must be conducted inside a Biological Safety Cabinet (BSC) Class II. Use face shield, surgical mask and eye protection for open bench work.

Hand washing procedures must be carefully followed.

Animal work should be conducted in the BSC. 

Risk assessment will be needed for procedures generating aerosols.

Spill Procedures

Small 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.
Large

For assistance, contact Emory’s Biosafety Officer (404-727-8863), or the EHSO Spill 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.
Reporting 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)

Viability

Disinfection

Salmonella Typhi is susceptible to 1% sodium hypochlorite, 70% ethanol, 3-6% hydrogen peroxide, and quaternary ammonium compounds.

Inactivation Sensitive to moist heat (121 °C for at least 15 minutes), dry heat (170 °C for at least 1 hour) and ozone.
Survival Outside Host Lettuce (63 days); parsley (231 days); pecans (32 weeks); refrigerated cheddar cheese (10 months); butter (9 months); frozen yogurt (63 days); frozen minced beef and chicken (20 weeks).

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 ­­­­Salmonella Typhi. Additional PPE may be required depending on lab specific SOPs.
Additional Precautions All procedures that may produce aerosols, or involve high concentrations or large volumes should be conducted in a biological safety cabinet (BSC). 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.

PDF (Full Document)

BARS PDF
Click the icon to download the PDF version of this BARS.