A
separate
sample is required - not to be shared with other faecal test requests. Send
a minimum of 1 g
of faeces to the laboratory immediately.
-
Only
1 loose or liquid faecal specimen
is needed for testing.
-
Testing is indicated only in a patient with 3 or more episodes of loose stools within 24 hours.
-
Test performed on
loose or liquid stools
(specimens that take the shape of the container) only.
-
Repeat testing of negative specimens will not be performed within a 14 day period without prior consultation with the Clinical Microbiologist.
-
Clearance specimens will not be processed.
Transport
The preferred specimen should be less than 24 hours old.
The specimen should be received by the laboratory within 3 hours of collection, otherwise it should be refrigerated. If delivery time is likely to exceed 48 hours, the specimen should be frozen and transported on dry ice.
Rejection Criteria
-
Specimens refrigerated for greater than 5 days.
-
Stools that do not take the shape of the container.
-
Specimens that have tested negative within the previous 14 days.
-
Specimens that have tested positive within the previous 30 days.
Clostridioides difficile
Clostridioides (Clostridium) difficile
are anaerobic, spore forming, gram-positive bacilli which are widespread in nature. The spores can survive for extended periods on inanimate surfaces in health care settings. These bacteria are acquired from the environment or transmitted via the faecal-oral route. Some
C. difficile
strains produce two enterotoxins, toxin A and toxin B that may damage the large intestine of the infected individual.
The major cause of
C. difficile infection (CDI)
is inappropriate antibiotic exposure. It is also associated with gastrointestinal surgery/procedures, long periods of hospitalisation, serious underlying illness, immunocompromised patients and advanced age.
Detection of
C. difficile
in the laboratory is performed using several diagnostic testing algorithms for CDI involving both toxin gene detection and toxin production. The tests performed will depend on risk factors and other testing requested.
Diagnostic approach for
C. difficile
Immunoassay results are reported as - Clostridioides difficile toxin: Positive or Negative.
Positive PCR results will be reported as - Clostridioides difficile toxin gene: Detected, Clinical correlation is required.
Negative PCR results will be reported as - Clostridioides difficile toxin gene: NOT detected.
Test of cure, clearance and relapse
Repeat testing
or
'test of cure'
serves no value as prolonged asymptomatic carriage in recovering or immune patients occurs. To assess response to treatment, clinical assessment is required. Repeat specimens from patients who have had positive
C. difficile
test within the last 30 days, will not be processed. If diarrhoea persists and
C.difficile
is suspected as a cause, please contact the clinical Microbiologist.
Clearance samples
are not required and have no place in removing patients from Contact Precautions. Patients with formed stool generally do not need to be in Contact Precautions.
Relapse
after completion of treatment occurs. Additional testing is not required if diarrhoea recurs. A further course of treatment is warranted.
Notification to Public Health
C. difficile
is notifiable to the Medical Officer of Health when occurring in two or more linked persons, a person in a high risk occupation (food handler, early childhood worker, <5 year old attending child care, health care worker), or any others at higher risk of transmission because of illness or disability.