Advanced Diagnostic Laboratories

Stool Culture

Test Code

CXSTO

Description

Stool culture is used to determine the presence of common bacteria that are the cause of acute gastroenteritis. Viruses and C. difficile are not included in this testing. For more rapid and comprehensive testing, consider utilizing molecular GI pathogen panels (GIDIF or GINCD).

Note that most pathogens cause self-limiting gastroenteritis and susceptibilities are not beneficial. In addition, susceptibility testing is contraindicated for E. coli O157:H7. Treatment with antibiotic for enterohemorragic colitis can induce bacterial cell lysis with the release of toxin, which may increase the risk of developing hemolytic uremic syndrome (HUS).

Collect

Stool: Collection of stool specimens should be during the acute or diarrheal stage of intestinal infection. Patient should pass stool in sterile pan, without urine or toilet paper touching the specimen. Toilet paper may contain barium salts, which are inhibitors to some fecal pathogens. Specimens may be sent as fresh stool in a sterile container or in Cary-Blair medium.

Rectal swab: Only acceptable for pediatric patients. Sterile swab should be inserted about 1 inch past the anal sphincter to collect the specimen. Place swab into Cary-Blair for transport to the laboratory.

Preferred volume: 3 mL
Minimum Volume: 2 mL

Patient Prep

Avoid recent antibiotics, x-ray contrast material, antidiarrheal medications, antacids, bismuth or oil products.

Unacceptable Conditions

Specimens received outside of temperature storage requirements
Specimens received outside of stability time frame
Specimens that do not meet the minimum volume requirement
Specimens not sent in sterile container or Cary-Blair medium
Specimens sent in expired Cary-Blair
Stool specimens that are hard or solid
More than one specimen per patient visit
Specimens from patients that have been admitted for more than 3 days
Specimens from a source not acceptable for this testing
Specimens that are excessively leaking
Mislabeled or unlabeled specimen

Stability

Unpreserved Stool:

For optimal recovery of potential pathogens, specimens should arrive within 2 hours at room temperature (20-25°C)
If transportation is delayed, specimens must be refrigerated (2-8°C) for a maximum of 24 hours

Preserved Stool:

Specimens should arrive within 24 hours at room temperature (20-25°C)
If transportation is delayed, specimens must be refrigerated (2-8°C) for a maximum of 2 days
If Shigella is suspected, the specimen should be stored at (2-8°C) the entire duration from collection to processing

Performed

7 days a week from 8am to 6 pm

Methodology

Conventional culture

Turnaround Time

3 days

Department

Microbiology Lab

Study Offerings

CAP/CLIA

Related Tests

GINCD, GIDIF

Reference Interval

No Salmonella, Shigella, Vibrio, Campylobacter, Aeromonas, Plesiomonas, Yersinia or E. coli O157:H7 isolated.

Interpretation

Threshold for Pathogenicity	Organism	Reporting
Any	Aeromonas spp.	ID
	Campylobacter spp.	ID
	E. coli O157:H7	ID
	Plesiomonas spp.	ID
	Salmonella spp.	ID and AST
	Shigella spp.	ID and AST
	Vibrio spp.	ID
	Yersinia spp.	ID
	Bacillus anthracis	ID
Pure or Predominant	Bacillus cereus	ID
Pure	Pseudomonas aeruginosa	ID and AST
	Staphylococcus aureus	ID and AST
	Yeast	ID