GAS Test (Rapid Strep Test)

1 What is a GAS Test (Rapid Strep Test)?

The rapid strep test (GAS test) determines quick and accurate whether or not strep bacteria are present in the patient's throat and also the presence of Streptococci in other infected areas (such as wound infections).

Sore throats can be caused by infection from either viruses or bacteria and the most common bacteria is streptococcus (GAS). The most common are affected children 5 to 15 years of age and during the winter/early spring season.

GAS infection can be differently presented by age.

Children < 1 year of age have low-grade fever (< 101 F, 38 C), fussiness, decreased appetite, often following exposure to either daycare or older infected siblings,children < 3 years of age) prolonged purulent nasal discharge, low grade fever, and enlarged and tender lymph nodes in the neck area and children (> 3 years of age) sudden onset sore throat, moderate fever (> 101 F, 38 C), headache, upset stomach, and enlarged and tender lymph nodes in the neck area.

The traditional test for a strep throat was a throat culture but the disadvantage was that the results take two to three days due to the time necessary to allow enough GAS bacteria to grow to enable accurate identification.

A rapid strep test is much quicker and can produce results within minutes. A cotton swab (similar to a Q-tip) is quickly rubbed over both tonsils as well as the back wall of the mouth (the posterior pharynx) and then the swab is placed in a specialized container and the rapid test is performed.

After testing, the patient can receive antibiotic treatment to quickly reduce the symptoms, shorten the duration of illness and quickly and efficiently eliminate the possibility of the spread of infection to others because serious consequences of streptococcal infections can occur (rheumatic fever associated with heart, joint and nervous system damage and serious kidney disease).

The limitation of the rapid strep test is that each manufacturer (there are several of them) has designed their test to respond only to the presence of the particular streptococcal bacteria (Group A) responsible for strep throat so other bacteria cannot be identified.

Since 5 of 100 patients with strep throat will be missed using a rapid strep test, all negative swab specimens should be sent for culture to confirm the absence of strep bacteria.