Laboratory Test Reference Guide

Adult patients who have been in hospital for more than 3 days and were not admitted with gastrointestinal symptoms, will only be tested for Clostridium difficile toxin.

• Do not routinely test for community gastrointestinal stool pathogens in hospitalized patients who develop diarrhoea after day 3 of hospitalization.
• Do not routinely collect or process specimens for Clostridium difficile testing when stool is non-liquid (i.e., does not take the shape of the specimen container)
• Do not routinely collect or process specimens for Clostridium difficile testing in infants less than one year of age with diarrhoea.
• Do not obtain a C. difficile toxin test to confirm “cure” if symptoms have resolved.

Specific investigations are not routinely required in the majority of patients with acute diarrhoea of up to 14 days duration.  Enteric pathogens may not be amenable to treatment; however in some situations they pose a public health risk.

A laboratory diagnosis is useful for people who:

• may have an infection* that could benefit from specific therapy; 
• are at risk of severe complications e.g. intestinal failure and short bowel syndrome;
• are at risk of spreading infection; e.g.. Food handlers  or
• are involved in an outbreak and may have a common source of infection.

*   For example in severe dehydration or with abdominal pain or if surgery is being contemplated, where detection of Campylobacter, Yersinia or enteric adenoviruses can change management. 

Stool culture also has a role in selected patients with suspected IBD to exclude infectious causes and in individuals who have recently travelled to countries with poor water or food services.

• Do not send stool for culture in every admission with, or who develops, diarrhoea. 
• Do not send stool for culture unless there are good clinical indications.

Stool testing for a range of pathogens is a particularly complex, resource intensive process.

Stool cultures have a low rate of pick up for identifying the likely pathogenic organism.

Samples requesting culture on patients that have been in hospital >3 days will be tested for Clostridium difficile toxin only i.e. not cultured.

**Enteric pathogens covered by culture include: Campylobacter, Salmonella, Shigella, Yersinia, Aeromonas, E.coli 0157, STEC E.coli.**

Grape/Walnut size sample.