Bacterial (Growing) Culture and STDs

Bacterial culture is simply a fancy way of saying "growing bacteria in a controlled setting." When doctors are trying to determine if a patient has a bacterial infection — whether it's in a wound, in their throat, or an STD,— they take a sample from the area they think is infected and put it in a special medium where the bacteria can grow. That medium is chosen based on what site the sample is taken from and which types of bacteria are most likely to be present.

This type of culture can be used to detect everything from strep throat to chlamydia, sometimes even when an infection has barely begun. In fact, a bacterial culture is a useful tool in a doctor's arsenal for just that reason.

Given a comfortable environment in which to do so, bacteria tend to multiply and thrive. This means that, over time, an undetectable number of bacteria that a doctor has sampled from an infected area (like a cut or an ulcer) can quickly multiply to a number that can be more readily observed and identified so that the right treatment can be selected.

Why It's the Gold Standard 

Most bacterial STDs can be detected by bacterial culture. Since culture can detect even very low numbers of bacteria in a simple, it has long been considered the gold standard test for chlamydia and gonorrhea.

However, bacterial culture requires special supplies and techniques, which means that it's not often done when doctors have other options for STD testing. In particular, it has been replaced by LCR and other DNA amplification tests on urine samples for chlamydia in gonorrhea. 

As these types of urine tests have become cheaper and more widely available, recognition of their efficacy has also been growing. In fact, some people now consider these tests to be another gold standard test alongside bacterial culture for some infections. They also have the advantage of being able to detect non-viable bacteria, where culture can only be used to detect living organisms.

Such DNA-based urine testing also may be helpful for the diagnosis and management of bacterial urinary tract infection (UTI).