Clostridioides difficile, or C. diff, is a bacterium causing severe diarrhea and colitis, an inflammation of the colon. This infection often occurs when gut bacteria are disrupted, frequently due to antibiotic use. C. diff releases toxins that irritate the intestinal lining, leading to symptoms like watery diarrhea and abdominal pain. Accurate diagnosis is important for determining appropriate treatment and preventing further spread. A stool test is a primary method to detect C. diff toxins or the bacteria itself, confirming if it causes a patient’s symptoms.
Required Sample Volume
The amount of stool needed for a C. diff test is generally small, though the precise quantity can vary slightly depending on the laboratory and the specific testing method used. Many laboratories request a sample approximately the size of a walnut, or 1 to 4 scoops using a provided collection device. This often translates to 1 to 2 milliliters (mL) for liquid stool, or around 5 grams (g) of solid stool, with a minimum of 0.5 mL or 0.5 g acceptable for liquid samples.
An adequate sample ensures sufficient material for accurate analysis, as C. diff tests look for bacterial toxins or genetic material. Too small a sample might lead to an insufficient concentration of target substances, potentially resulting in a false-negative result. C. diff toxins degrade quickly at room temperature, making timely and sufficient sample collection important for reliable outcomes.
Proper Sample Collection
Careful attention to detail during collection ensures the sample’s integrity and accurate results. Begin by preparing a clean collection area, often with a kit from your healthcare provider. Avoid contamination with urine or toilet water; urinate before collecting. Use plastic wrap over the toilet bowl or a clean bedpan to catch stool without it touching water.
Once passed, use the provided scoop to transfer the required amount into the sterile container. Focus on collecting diarrheal or unformed portions, as these are most relevant. Securely close the container, avoiding overfilling.
Proper labeling is important; clearly write your full name, date of birth, and the exact date and time of collection to ensure correct identification. After handling, wash your hands thoroughly.
Transport the collected sample to the laboratory as soon as possible, ideally within an hour, to preserve toxin stability. If immediate transport is not possible, refrigerate the sample at 2-8°C (36-46°F) for no longer than 24 to 72 hours, depending on guidelines. Refrigeration is generally preferred for toxin stability. An ice pack can help maintain temperature during longer transport.
Understanding Your Results
Your healthcare provider will interpret C. diff test results in the context of your symptoms and medical history. A positive test result indicates C. diff toxins or their genes in your stool, suggesting these bacteria are responsible for your symptoms. This typically leads to a C. diff infection diagnosis and specific treatment.
A negative test result generally means no signs of C. diff infection were detected. While this often suggests another cause, if symptoms persist, your healthcare provider may consider additional testing or explore other potential causes.
It is important to differentiate between active infection and colonization. Some tests detect C. diff bacteria even without toxin production. If bacteria are present but toxins are not, it may indicate colonization, where bacteria reside in the gut without causing illness. Colonization usually does not require treatment; the focus is on active infection with toxin production and symptoms.
For a positive diagnosis, your provider will discuss treatment, often involving discontinuing contributing antibiotics and initiating a C. diff-specific antibiotic. Hydration is also important for fluid loss. For persistent symptoms with negative results, your provider will investigate other causes. A “test of cure” after treatment is generally not recommended, as bacteria can remain after symptoms resolve, and retesting may lead to unnecessary treatment.