Stool Culture

Stool or rectal swab

1 g, 1 mL, or one swab in stool C&S transport vial (usual bacterial swab transport is not acceptable although the swab may be used)

Stool culture transport vial is required; diapers are not acceptable. Culture collection swab may be used to collect rectal swabs or a swab of fecal material, then swab should be placed in stool culture transport vial (Para-Pak® C&S orange).

Detect bacterial pathogenic organisms in the stool; diagnose typhoid fever, enteric fever, bacillary dysentery, Salmonella infection.

Indications for stool culture include:¹

• Bloody diarrhea

• Fever

• Tenesmus

• Severe or persistent symptoms

• Recent travel to a third world country

• Known exposure to a bacterial agent

• Presence of fecal leukocytes

Yersinia sp and Vibrio parahaemolyticus will not be isolated unless specifically requested; these will each be done with an additional charge. These organisms are fastidious and have very specific requirements for growth.

Aerobic culture on selective media; detection of EHEC Shiga-like toxins by enzyme immunoassay (EIA)

In enteric fever caused by Salmonella typhi, S choleraesuis, or S enteritidis, blood culture may be positive before stool cultures, and blood cultures are indicated early; urine cultures may also be helpful.

Diarrhea is common in patients with the acquired immunodeficiency syndrome (AIDS). It is frequently caused by the classic bacterial pathogens as well as unusual opportunistic bacterial pathogens and parasitic infestation. (Giardia, Cryptosporidium, and Entamoeba histolytica frequently reported.) Cryptosporidium, Isospora, and Pneumocystis can occur with AIDS. Rectal swabs are useful for the diagnosis of Neisseria gonorrhoeae and Chlamydia infections. AIDS patients are also subject to cytomegalovirus, Salmonella, Campylobacter, Shigella, C difficile, herpes, and Treponema pallidum gastrointestinal tract involvement.

In acute or subacute diarrhea, three common syndromes are recognized: gastroenteritis, enteritis, and colitis (dysenteric syndrome). With colitis, patients have fecal urgency and tenesmus. Stools are frequently small in volume and contain blood, mucus, and leukocytes. External hemorrhoids are common and painful. Diarrhea of small bowel origin is indicated by the passage of few large volume stools. This is due to accumulation of fluid in the large bowel before passage. Leukocytes indicate colonic inflammation rather than a specific pathogen. Bacterial diarrhea may be present in the absence of fecal leukocytes and fecal leukocytes may be present in the absence of bacterial or parasitic agents (ie, idiopathic inflammatory bowel disease).² See table. Although most bacterial diarrhea is transient (1 to 30 days) cases of persistent symptoms (10 months) have been reported. The etiologic agent in the reported case was Shigella flexneri diagnosed by culture of rectal swab.³ In infants younger than one year of age, a history of blood in the stool, more than 10 stools in 24 hours, and temperature greater than 39°C have a high probability of having bacterial diarrhea.^4,5 Diarrhea is also a common side effect of long-term antibiotic treatment. Although often associated with Clostridium difficile, other bacteria and yeasts have been implicated.⁶