Medical Q&As

Vaginal swab - culture and sensitivity?

What is my GP looking for when she sends me for a vaginal swab for culture and sensitivity?

A vaginal swab test involves taking a sample of vaginal secretions with a device that looks like a cotton bud. The swab, with secretions attached, is then placed in a special container and sent to the microbiology laboratory for further analysis. When it reaches the laboratory the sample is then plated on a Petrie dish, which is a flat dish containing a special jelly. The dish is then placed in a special incubator that maintains a particular level of heat and humidity, which facilitates the growth of any bacteria that may be contained in the sample. The jelly in the Petrie dish is a nutrient material that allows any bacteria in the sample to colonise the surface of the jelly. This is the process that is referred to when we send a swab for culture. In other words the lab technician is attempting to make the bacteria reproduce and multiply by creating a favourable yet artificial environment. Having succeeded in creating the bacterial colonies on the Petrie dish various antibiotics are then added to the dish to determine which antibiotics are the most effective in eliminating the bacterial colonies from the dish. Therefore culture and sensitivity simply refers to the process whereby the bacteria in the sample are identified and then tested to determine which antibiotics are needed to eliminate them. “Culture and sensitivity” testing is widely used in microbiology for testing such diverse samples as various bodily discharges to urine samples.