Salmonella enterica Spp. (Serotype Enteritidis, Typhi)

Characteristics
Morphology	S. enterica contains the vast majority of serotypes associated with human disease. S. enterica serotype Typhi, commonly designated S. Typhi, and is the causative agent of typhoid fever. Untreated case mortality for typhoid fever is >10%. S. Typhi is a motile, Gram-negative, enteric bacterium that is easily cultivated on standard bacteriologic media, although enrichment and selective media may be required for isolation of this organism from clinical materials. S. enterica serotype Paratyphi (S. Paratyphi) is also considered a typhoidal serovar causing a similar illness.
Growth Conditions	The most commonly used media selective for Salmonella are SS agar, bismuth sulfite agar, Hektoen enteric (HE) medium, brilliant green agar and xyloselisine-deoxycholate (XLD) agar.

Characteristics

Morphology

S. enterica contains the vast majority of serotypes associated with human disease. S. enterica serotype Typhi, commonly designated S. Typhi, and is the causative agent of typhoid fever. Untreated case mortality for typhoid fever is >10%. S. Typhi is a motile, Gram-negative, enteric bacterium that is easily cultivated on standard bacteriologic media, although enrichment and selective media may be required for isolation of this organism from clinical materials. S. enterica serotype Paratyphi (S. Paratyphi) is also considered a typhoidal serovar causing a similar illness.

Growth
Conditions

The most commonly used media selective for Salmonella are SS agar, bismuth sulfite agar, Hektoen enteric (HE) medium, brilliant green agar and xyloselisine-deoxycholate (XLD) agar.

Health Hazards
Host Range	Humans are the only host for Salmonella Typhi. Domestic and wild animals host S. enterica nontyphoidal 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	For non-typhoidal salmonellosis, the infectious dose is approximately 103 bacilli. For enteric fever, the infectious dose is about 105 bacilli by ingestion. Patients with achlorhydria, depressed cell-mediated immunity, or who are elderly may become infected with at a lower infectious dose
Incubation Period	For non-typhoidal salmonellosis, the incubation period is variable, depends on the inoculum size, and usually ranges between 5 and 72 hours. For typhoid fever, the incubation period can be between 3 and 60 days, although most infections occur 7-14 days after contamination.

Medical Precautions/Treatment
Prophylaxis	Clean water supplies, hand hygiene, sanitation, avoid eating raw eggs or unpasteurized milk. Antibiotics can be used as prophylaxis in at-risk individuals.
Vaccines	There are three vaccines available, but are only given to individuals who will be at risk of exposure
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. Diagnosed when a laboratory test detects Salmonella bacteria in stool, body tissue, or fluids.
GWU Requirements	Report all incidents to the Office of Risk Management as well as the Office of Research Safety (ORS) IMMEDIATELY FOLLOWING THE OCCURRENCE.

BSL-3

Containment
BSL-2/ABSL-2	Risk Group 2 classification. BSL-2 practices, containment equipment, and facilities are recommended for activities using clinical materials and diagnostic quantities of infectious cultures. ABSL-2 facilities, practices, and equipment are recommended for activities with experimentally infected animals.
BSL-3	BSL-3 practices and equipment are recommended for activities likely to produce significant aerosols or for activities involving production quantities of organisms.

Spill Procedures
Small Spills (<1 liter)	If the spill occurred inside a biological safety cabinet, close the sash and allow the cabinet to operate for 15 minutes before continuing with the spill cleanup. Salmonella is not commonly transmitted via aerosols, but caution should be taken during a spill outside of a BSC since it can contaminate surfaces. Leave the room immediately and allow the aerosols to dissipate for 15 minutes. Notify others working in the lab. Don appropriate PPE. Cover area of the spill with paper towels or any absorbent material and apply an EPA registered disinfectant effective against the bacteria (bleach, ethanol, glutaraldehyde), working from the perimeter towards the center. Allow 30 minutes of contact time before disposal and cleanup of spill materials.
Large Spills	Alert lab personnel in the laboratory to the spill and keep people out of the area to prevent spread of the contamination. Check if you have been contaminated or if any of your PPE has been breached. If so follow exposure procedures. Remove any contaminated clothing and place it the biohazard waste. Wash your hands and post a sign on the door. Notify your supervisor of the incident and call ORS (4-8258) for assistance. If the situation involves an imminently life-threatening injury or has catastrophic potential, call 911.

Spill Procedures

Small Spills (<1 liter)

If the spill occurred inside a biological safety cabinet, close the sash and allow the cabinet to operate for 15 minutes before continuing with the spill cleanup.

Salmonella is not commonly transmitted via aerosols, but caution should be taken during a spill outside of a BSC since it can contaminate surfaces. Leave the room immediately and allow the aerosols to dissipate for 15 minutes. Notify others working in the lab. Don appropriate PPE. Cover area of the spill with paper towels or any absorbent material and apply an EPA registered disinfectant effective against the bacteria (bleach, ethanol, glutaraldehyde), working from the perimeter towards the center. Allow 30 minutes of contact time before disposal and cleanup of spill materials.

Large Spills

Alert lab personnel in the laboratory to the spill and keep people out of the area to prevent spread of the contamination. Check if you have been contaminated or if any of your PPE has been breached. If so follow exposure procedures. Remove any contaminated clothing and place it the biohazard waste. Wash your hands and post a sign on the door. Notify your supervisor of the incident and call ORS (4-8258) for assistance. If the situation involves an imminently life-threatening injury or has catastrophic potential, call 911.

Exposure Procedures
Mucus Membrane	Flush eyes, mouth or nose for 15 minutes at eyewash station.
Other Exposure	For an area not protected by skin, wash with soap and water for 15 minutes (open wounds, sores, etc.)
Reporting	Report ALL injuries to the PI immediately and reported to the Office of Risk Management at [email protected] IMMEDIATELY FOLLOWING THE OCCURRENCE. Exposures that involve a bloodborne-pathogen or recombinant DNA also need to be reported to the Office of Research Safety at [email protected]. If the injury requires immediate medical attention, call GWPD at 202-994-6111 or call 911.
Medical Monitoring	Seek immediate medical evaluation, treatment, and post exposure follow-up at the Employee Health Office at GWU Hospital (900 23rd St., NW, Suite G-1090, Phone: 202-715-4275). Students should go to the Students Health Office at Marvin Center. After hours treatment can be received at the GWU hospital emergency room.

Stability
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. Higher containment levels will require donning scrubs and wearing respiratory protection.
Additional Precautions	Additional protection may be worn over laboratory clothing when infectious materials are directly handled, such as solid-front gowns with tight fitting wrists, gloves, and respiratory protection. Wash hands with soap and water after removing gloves.

References
CDC (https://www.cdc.gov/salmonella/) BMBL 6th Edition (https://www.cdc.gov/labs/BMBL.html) Canadian PHAC (https://www.canada.ca/en/public-health/services/laboratory-biosafety-bi…)