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Stool Culture

Salmonella, Shigella, Campylobacter, Fecal culture, O157:H7, EHEC, Stool for E. coli, Hemorrhagic E. coli, Shiga Toxin, Enterohemorrhagic E. coli, Stool Culture

Test Codes

EPIC: LAB1231037

Department

Microbiology

Instructions

• This test only detects Salmonella, Shigella, Campylobacter, E. coli O157:H7 and the presence of Shiga Toxin. 
• For Vibrio requests, order Culture, Vibrio (LAB1231197)
• For Yersina requests, order Culture, Yersinia (LAB1231196) 
• For Clostridium difficile, see C. difficle Toxin. 
• For parasites, see Ova and Parasite. 
• For Fecal Lactoferrin/Leukocyte, see Fecal Lactoferrin Assay.

• Stool culture will NOT be performed on inpatients hospitalized greater than three days.  Exceptions will be granted on a case-by-case basis. Please contact the System Director or Associate Director of the Microbiology Laboratory

Specimen Collection Criteria

Collect: Random stool specimen, about the size of a walnut, placed in a container with Para-Pak/Cary-Blair transport medium. Specimens not in Para-Pak/Cary-Blair transport medium must be placed in a sterile collection container, refrigerated, and sent to the Laboratory immediately.

• Do not contaminate the exterior of the container with the specimen.
• Do not place toilet tissue in the container with the specimen.
• Do not contaminate the specimen with urine.
• If the patient has taken antibiotics, barium, oil, or magnesium compounds, delay the collection of stool specimens for at least 7 days.
• Rectal swabs (pediatric stool only) and stool aspirates are acceptable for stool cultures but the Shiga toxin testing cannot be performed on them.

Physician Office/Draw Specimen Preparation

Stool in Para-Pak/Cary-Blair transport medium — maintain at room temperature (20-26°C or 68-78.8°F).

Stool NOT in Para-Pak/Cary-Blair transport medium — must be refrigerated (2-8°C or 36-46°F) and received in the Laboratory within 2 hours of collection – NO EXCEPTIONS.

Preparation for Courier Transport

Transport: Stool specimen in Para-Pak/Cary-Blair medium at room temperature (20-26°C or 68-78.8°F).

Rejection Criteria

• Unpreserved specimens (regardless of temperature storage) received in the laboratory more than 2 hours after collection.
• Frozen specimens (preserved or unpreserved).
• Stool collected following a soap suds enema.
• Stool containing barium from a previous x-ray.
• Stool in diapers.
• Rectal swabs and endoscopy specimens are unacceptable for Shiga toxin testing.
• Stool culture on inpatients that have been hospitalized greater than three days.
• The Laboratory will only test one specimen per patient per 24-hour period.
• The Laboratory will not test more than two specimens per patient per diarrheal episode without prior consultation with one of the Microbiology Laboratory directors.

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 2 hours (Unpreserved)
Room Temperature (20-26°C or 68-78.8°F): 72 hours (Preserved/Para-Pak/Cary-Blair)

Refrigerated (2-8°C or 36-46°F): 2 hours (Unpreserved)
Refrigerated (2-8°C or 36-46°F): 72 hours (Preserved/Para-Pak/Cary-Blair)

Frozen (-20°C/-4°F or below): Unacceptable (Unpreserved or Preserved/Para-Pak/Cary-Blair)

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 4 days

Laboratory

Royal Oak Microbiology Laboratory

Performed

Sunday – Saturday.
Preliminary results available within 1-2 days.
Final negative results available within 2 days.
Shiga toxin results available within 24 hours.

Reference Range

No Salmonella, Shigella, Campylobacter, Aeromonas or Plesiomonas recovered.
Negative for Shiga toxin producing E. coli. 

Test Methodology

Culture, Immunochromatographic Assay.

Interpretation

Salmonella, Shigella, Campylobacter, Aeromonas, Plesiomonas and Shiga toxin producing E. coli are infectious agents known to cause diarrhea. These bacteria affect patients of all ages.

Asymptomatic carriage of Campylobacter and Shigella are uncommon.

Clinical Utility

Stool cultures can facilitate the diagnosis of Aeromonas, Campylobacter, Plesiomonas Salmonella, Shigella, Vibrio and Yersinia infections. Toxin testing further assists in the detection of Shiga toxin producing enterohemorrhagic E. coli. 

Incubation Period

Aeromonas: 
Campylobacter: 1-7 days or longer. 
Plesiomonas:  
Salmonella: 6-72 hours for gastroenteritis. 3-60 days (average 7-14 days) for enteric fever. 
Shigella: 1-7 days (average of 2-4 days). 
Vibrio:
Yersinia: 
E. coli: 3-4 days (range of 1-10 days).

Transmission

Transmission of these pathogenic bacteria is usually through the fecal-oral route, contaminated foods, and domestic and wild animals.

Reference

1. Pillai, D.R., 2016. Fecal Culture for Aerobic Pathogens of Gastroenteritis. In: Clinical Microbiology Procedures Handbook. Procedures Handbook. 4^th ed. Leber, A.L., Ed-in-Chief. ASM Press. Washington, D.C.
2. Pillai, D.R., 2016. Fecal Culture for Campylobacter and Related Organisms. In: Clinical Microbiology Procedures Handbook. Leber, A.L., Ed-in-Chief. ASM Press. Washington, D.C.
3. Siegel, D.L. et al, 1990. Inappropriate Testing for Diarrheal Diseases in the Hospital. JAMA, 263:979-982.

CPT Codes

87045 (Culture), 87427x2 (Shiga Toxin). Additional charges may be incurred for identification and susceptibility testing.
LOINC:  625-4, Vibrio 6578-9, Yersinia 701-3

Contacts

Last Updated

9/30/2024