What is it?

A culture and sensitivity test, also known as a C&S test, is a two-part diagnostic procedure used to identify the cause of an infection and determine the most effective treatment. It's commonly used for diagnosing infections of the:

• Urinary tract (urinary tract infection - UTI)

• Blood (bacteremia)

• Wounds (skin infection)

• Respiratory tract (pneumonia)

• Gastrointestinal tract (diarrhea)

• Other body fluids or tissues depending on the suspected infection site

Here's how the C&S test works:

Part 1: Culture

1. Sample Collection: A healthcare professional will collect a sample of fluid, tissue, or discharge suspected to be infected. This may involve a swab, urine sample, blood draw, or a sample from a wound depending on the suspected source.

2. Culturing the Sample: The collected sample is placed on a special growth medium in a laboratory dish. This medium provides nutrients that allow any bacteria or fungus present in the sample to grow.

3. Observation and Identification: The laboratory professionals monitor the dish for growth. If bacteria or fungus grow, they will identify the specific organism using various techniques like microscopy or biochemical tests.

Part 2: Sensitivity Testing

1. Antibiotic Exposure: Once the organism is identified, the lab exposes it to different antibiotics.

2. Growth Inhibition: They observe which antibiotics inhibit the growth of the bacteria or fungus. This helps determine which antibiotics will likely be most effective in treating the infection.

Interpreting the Results:

• Culture Result:

  • Negative: No bacteria or fungus were identified in the sample, suggesting a non-infectious cause or the organism wasn't detected by the test.

  • Positive: Bacteria or fungus were identified in the sample, indicating an infection. The report will specify the type of organism found.

• Sensitivity Result:

  • Sensitive: The identified organism is susceptible to certain antibiotics listed in the report. These antibiotics are likely to be effective in treating the infection.

  • Intermediate: The organism shows some resistance to a particular antibiotic. Further evaluation may be needed to determine if this antibiotic can be used effectively.

  • Resistant: The organism is resistant to a particular antibiotic. This antibiotic will likely not be effective in treating the infection.