What is a Strep A Rapid Test?

A Strep A rapid test is a diagnostic test used to detect antigens from Group A Streptococcus (GAS) bacteria, the most common bacterial cause of strep throat. Because the test identifies bacterial antigens rather than waiting for bacteria to grow in a laboratory, results are typically available within 10 to 20 minutes.¹ This makes it a quick and convenient way to diagnose strep throat. In our guide below, we'll explain everything you need to know about how these rapid tests work, as well as when and why they are used.

How does a Strep A Rapid Test Work?

Strep A rapid tests are a useful diagnostic tool for healthcare providers in the diagnosis of streptococcal pharyngitis, commonly known as strep throat. The test involves taking a throat swab, which is then analysed for the presence of the bacteria. Specifically, a sample is collected from the back of the throat and tonsils using a sterile swab.

The sample is then placed into a rapid test device that detects antigens produced by Group A Streptococcus bacteria. The test results are interpreted based on the visual indicator that shows the presence or absence of the bacteria.

Many point-of-care strep A testing kits are designed to simplify this process by including the necessary swabs, reagents, and testing materials in one package. For example, the Strep A Rapid Test Kit (25 tests) is designed for use in pharmacies, physician offices, walk-in clinics, and other testing environments where rapid results are needed.

When is a Strep A Rapid Test Used?

Healthcare providers commonly perform the test when patients have symptoms associated with strep throat, including:

• Sudden sore throat
• Pain when swallowing
• Fever
• Swollen lymph nodes
• Red or swollen tonsils
• White patches or streaks on the tonsils
• Small red spots (petechiae) on the roof of the mouth¹

The test is particularly useful for diagnosing strep throat in children, who are more prone to the infection. 

How Accurate is a Strep A Rapid Test?

Although Rapid Strep A tests are highly specific, a negative result does not always rule out strep throat, because rapid antigen tests may not detect every infection. If symptoms strongly suggest a bacterial infection, healthcare providers may recommend a follow-up throat culture or molecular test for confirmation.² These tests are more sensitive but typically requires 24 to 48 hours for results.¹

Why Use a Strep A Rapid Test?

Because most sore throats are caused by viral infections rather than bacteria, a Strep A rapid test helps healthcare providers determine whether a patient's symptoms are caused by group A streptococcal bacteria. This enables clinicians to distinguish bacterial infections that may benefit from antibiotic treatment from viral sore throats, which do not respond to antibiotics.² By supporting timely and appropriate treatment decisions, rapid Strep A tests also promote responsible antibiotic use and help reduce unnecessary antibiotic prescribing.

Strep A Rapid Testing in Clinical Practice

In conclusion, a strep A rapid test is a useful diagnostic tool for healthcare providers in the diagnosis of strep throat. It provides quick and convenient results and is particularly useful for diagnosing strep throat in children. Since Group A Streptococcus spreads through respiratory droplets and close contact, good hand hygiene, covering coughs and sneezes, and avoiding sharing cups or utensils can help reduce transmission.