Lab Dept:

Microbiology/Virology

Test Name:

STOOL CULTURE

General Information

Lab Order Codes:

STLC

Synonyms:

Culture, E. coli 0157; Culture, Campylobacter sp.; Culture, Salmonella sp.; Culture, Shigella sp.; Feces Culture; Enterohemorrhagic E.coli (EHEC) for Shiga toxin

CPT Codes:

87045 – Culture, bacterial; feces, with isolation and preliminary examination, Salmonella and Shigella species
87046 x2 – Culture, bacterial; stool, additional pathogens, isolation and preliminary examination, each plate (e.g. Campylobacter, E. coli 0157)
87899 & 87899-59 – Infectious agent, not otherwise specified (EHEC)
87015 – Concentration (any type), for infectious agents (EHEC)

The following testing may be added if appropriate based on findings for organism identification (multiple additions are possible if more than one organism is identified).

87046 – For each individual additional pathogen (e.g. Yersinia, Vibrio, Aeromonas if appropriate)
87077 – Aerobic isolate, additional methods required for definitive identification of isolates (if appropriate)
87106 – Culture, fungi definitive identification, each organism; yeast (if appropriate)

Test Includes:

Culture for Salmonella, Shigella, Campylobacter and E. coli 0157; EHEC assay for Shiga toxins 1 (SLT1) & 2 (SLT2)

Logistics

Lab Testing Sections:

Microbiology

Phone Numbers:

Minneapolis:

Saint Paul:

612-813-5866

651-220-6555

Test Availability:

Daily, 24 hours. Requests are limited to one specimen per day.

Turnaround Time:

Culture: Preliminary report available at 1 day, final report within 3 - 5 days.
EHEC Immunoassay: 16 – 24 hours

Special Instructions:

● Other enteric pathogens such as Yersinia, Aeromonas, Staphylococcus, or Vibrio must be specifically requested since special isolation procedures are required.
●The EHEC assay has not been validated for and will not be performed on: Stool received in transport media (with the exception of Cary-Blair); Rectal swabs; Stool received in preservatives (such as SAF, PVA or formalin); endoscopy stool aspirates
●The EHEC assay will not be performed on: Gram negative (GN) broths that do not exhibit growth after the incubation period.
● Culture for predominant organism must be specifically requested since special isolation procedures are required. Coagulase-negative staphylococci will be identified on infants whose diagnosis is necrotizing enterocolitis (NEC) if requested.

● Specimen site and date/time of collection are required for processing.

Specimen

Specimen Type:

Fresh random stool preferred or rectal swab

Note: The EHEC assay will not be performed on endoscopy stool aspirates or rectal swabs; only a culture for Salmonella, Shigella, Campylobacter and E.coli 0157 will be performed.

Container:

Plastic, leakproof container or swab transport system; Para-Pak® C&S system (Cary-Blair transport media) for delayed transport of more than 1 hour (available in Microbiology)

Volume:

2 grams formed stool or 2 mL liquid stool

Collection:

Submit up to 3 specimens (1 per day) during the first 3 days of illness.

Fresh Stool:

1. Collect fresh, diarrheal stool in a clean, dry bedpan or on a newspaper over the toilet. Do not contaminate with urine, residual soap or disinfectants.
2. Transfer to a plastic, leakproof container.
3. Those portions of stool containing blood and mucous are especially significant and should be transferred into the container.
4. Specimens in diapers are not acceptable. Pediatric patients with severe diarrhea may use a U bag collection system. Place the bag over the anal area in an attempt to retrieve the specimen before it soaks into the diaper. The diaper can also be reversed with the plastic side toward the skin to prevent the specimen from soaking into the diaper. Transfer specimen into a plastic, leakproof container.
5. If there is a delay in transport of more than 1 hour, preserve specimen in a Para Pak® (C & S) orange vial. Refer to Special Processing.

Rectal Swab:

1. Insert swab approximately 1 inch into anal canal.
2. Gently move the swab from side to side to sample the anal crypts. Feces should be evident on the swab.
3. Place swab in transport medium.

Transport/Storage:

Transport fresh, unpreserved specimens to the Microbiology Laboratory within 1 hour at room temperature. Return specimens preserved in Para Pak® (C & S) within 72 hours of collection.

Special Processing:

Instructions for Para Pak® (C & S) system when delayed transport >1 hour is expected:

1. Fill vial by using the spoon built into the lid of the vial and transferring small scoopfuls of stool from areas which appear bloody, slimy or watery until the contents rise to the “Fill Here” red line. Do not overfill.
2. If the stool is formed, sample small amounts from each end, sides and the middle.
3. Mix the contents of the vials with the spoon. Screw cap on tightly and shake the vial vigorously until the contents are well mixed. Make sure there is no leakage.
4. Label vials with patient’s name, date and time of collection.
5. Store vials at room temperature.
6. Return collection kit to laboratory within 72 hours.

Sample Rejection:

No diapers accepted. Fresh, unpreserved specimens with a transit time exceeding 2 hours after collection; multiple specimens collected on the same day; improperly labeled specimen; specimen contaminated with urine and/or water; leaking container; insufficient volume; specimen containing interfering substances such as castor oil, bismuth, Metamucil®, barium, Vaseline®, or other cream contaminants. If an unacceptable specimen is received, the physician or nursing station will be notified and another specimen will be requested before the specimen is discarded.

Interpretive

Reference Range:

No Salmonella, Shigella, Campylobacter or E. coli 0157 isolated.
No Aeromonas or Yersinia isolated if specifically requested.
Negative for SLT1; Negative for SLT2

Alert Value:

Cultures that are positive for Salmonella, Shigella, E. coli O157, and Campylobacter spp. or positive ShigaToxin GN broth cultures will be called to the physician or patient’s nurse.

Methodology:

Salmonella, Shigella, Campylobacter, E. coli 0157: Culture
EHEC: Immunoassay for SLT1 & SLT2

Contraindications:

Stool cultures on patients hospitalized ≥3 days are not productive and should not be ordered unless special circumstances exist. If patient’s length of stay was >3 days and admitting diagnosis was not gastroenteritis, consider Clostridium difficile toxin.

References:

Weissfeld, A and Baselski, V (2010) Specimen receipt and accessioning. Section 1. Aerobic bacteriology, 1.2.1-4. In LS Garcia (ed) Clinical Microbiology Procedures Handbook. American Society for Microbiology, Washington DC

Miller, J Michael (1999) A Guide To Specimen Management in Clinical Microbiology, American Society for Microbiology, Washington DC

Miller, J Michael, and HT Holmes (1999) Specimen Collection, Transport, and Storage In PR Murray et al, (ed), Manual of Clinical Microbiology, 7th edition, American Society for Microbiology, Washington DC, pp 33-104

Blankenheim, T (2011) Shiga Toxin Detection, Version 1.0, Children’s Service Online Manual

Meridian Diagnostics, Inc, Cincinnati OH, ImmunoCard STAT! EHEC pkg insert, SN11169CLSI 1/07

Updates:

3/24/2010: CPT Updates
6/27/2011: Addition of EHEC Shiga toxin assay testing to stool culture.
6/20/2012: Addition of Alert Value