Skin Health Fungal, Bacterial & Viral Infections How Cultures Are Used to Diagnose a Multitude of Ailments By Heather L. Brannon, MD Heather L. Brannon, MD Heather L. Brannon, MD, is a family practice physician in Mauldin, South Carolina. She has been in practice for over 20 years. Learn about our editorial process Updated on June 16, 2021 Medically reviewed Verywell Health articles are reviewed by board-certified physicians and healthcare professionals. These medical reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Leah Ansell, MD Medically reviewed by Leah Ansell, MD LinkedIn Leah Ansell, MD, is board-certified in cosmetic and medical dermatology. She is an assistant professor at Columbia University and works in private practice in New York City. Learn about our Medical Expert Board Print A culture is a method used to identify the organisms suspected of causing an infection. Cultures are used to identify infectious microbes from urine, stool, genital tract, throat and skin samples. In dermatology, a culture test is used to determine whether a rash is caused by an infection and what organism is responsible. Sean Gallup / Getty Images What Is a Culture? A culture test identifies the cause of infection and allows the doctor to make a more accurate diagnosis and prescribe medication accordingly. A culture consists of the following: A container. Common containers include Petri dishes and test tubes.Culture medium. This is the "goo" that the organisms grow in. There are more than 100 different types of culture media designed to provide the optimum environment for a particular organism to grow, from salt, to sugar, to minerals, to agar, a gelling agent used to make solid cultures.A sample. A culture must include a tissue or fluid sample suspected of being infected. When a doctor orders a culture, he or she has to specify the type of organism suspected. Sometimes this is easy: a bacterial culture on an abscess or a viral culture on a genital ulcer that looks like herpes. When it's not as clear what type of organism is involved, the doctor may order several types of cultures, like a tissue culture and a fungal culture for an unusual-looking rash. If the culture identifies the organism, the organism might be exposed to different medications to see which ones are most effective. This is known as determining the sensitivity of the organism. Types of Cultures There are three types of cultures: solid, liquid and cell. Solid culture. Bacteria and fungi grow on a surface comprised of nutrients, salts, and agar, which is derived from algae. A single microbe is enough to grow an entire colony made up of thousands of cells, which is what makes solid cultures particularly useful. Different organisms will exhibit different colors, shapes, sizes and growth rates, helping microbiologists make an accurate diagnosis.Liquid culture. A liquid culture is grown in a liquid mixture of nutrients. The more organisms present in the culture, the more quickly the liquid becomes cloudy. Liquid cultures aren't as useful as solid cultures because there are often several different types of organisms present, making it hard to pinpoint a specific one. They are most commonly used to diagnose parasitic infections.Cell culture. In a cell culture, human and animal cells are used to infect the cell culture with the organisms present. Diagnosis is based on how the cells are affected. Cell culture tests are more involved that solid and liquid cultures, so they are used as a secondary method. Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit 0 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. "Culture." Dorland's Illustrated Medical Dictionary, 31st Ed. Philadelphia: Saunders, 2007. "Culture." Stedman's Medical Dictionary, 28th Ed. Baltimore: Lippincott Williams & Wilkins, 2006. 469.