Abdominal and gastrointestinal infections

Intra-abdominal infection, including biliary tract and peritonitis secondary to GI perforation

• If source of infection not immediately accessible, a blood culture is a useful surrogate sample
• Fluid or pus or tissue in universal container (white) obtained in theatre or at drainage for microscopy and culture
• Swabs (black) are a less useful sample with a poorer diagnostic yield compared to fluid or pus in a universal container

Microscopy is not performed out-of-hours, any samples received over night will be processed the next morning

Spontaneous bacterial peritonitis (SBP)

• Ascitic fluid in universal container (white) for microscopy and culture
• Ascitic fluid in blood culture bottles - recovery of some organisms may be improved

Suspected Clostridium difficile infection (CDI)

• Stool for C. difficile screen and toxin testing

See local guidance on AthenA for interpretation

Suspected E. coli O157 infection

• Stool for culture
• FBC and blood film
• Serum LDH
• Baseline renal function

Blood film may show evidence of haemolysis

Serum LDH is a marker of haemolysis

Acute gastroenteritis

• Stool for culture
• Vomitus or stool for norovirus PCR if requested by Infection Prevention and Control team (IPCT)

Include any relevant travel history in the clinical details

Send a specimen if:

• The patient is systemically unwell;
• There is blood or pus in the stool;
• The patient is immunocompromised;
• Diarrhoea developed following high risk foreign travel (request examination for ova, cysts, and parasites);
• If the patient is at risk of Clostridium difficile infection, e.g. following recent antibiotic treatment or hospitalisation;
• Diarrhoea persists for >1 week

Testing for norovirus is usually only performed in the context of a suspected outbreak