Throat culture

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Throat culture
Purposediagnose bacteria or fungal infection in throat

A throat culture is a laboratory diagnostic test that evaluates for the presence of a bacterial or fungal infection in the throat. A sample from the throat is collected by swabbing the throat and placing the sample into a special cup (culture) that allows infections to grow. If an organism grows, the culture is positive and the presence of an infection is confirmed. The type of infection is found using a microscope, chemical tests, or both. If no infection grows, the culture is negative. Common infectious organisms tested for by a throat culture include Candida albicans known for causing thrush and Group A streptococcus known for causing strep throat, [1] scarlet fever, and rheumatic fever. [1] Throat cultures are more sensitive (81% sensitive) than the rapid strep test (70%) for diagnosing strep throat, but are nearly equal in terms of specificity. [1]

Contents

Purpose

A throat culture may be done to investigate the cause of a sore throat. Most sore throats are caused by viral infections. However, in some cases the cause of a sore throat may be unclear and a throat culture can be used to determine if the infection is bacterial. Identifying the responsible organism can guide treatment.

Technique

The person receiving the throat culture is asked to tilt his or her head back and open his or her mouth. The health professional will press the tongue down with a tongue depressor and examine the mouth and throat. A clean swab will be rubbed over the back of the throat, around the tonsils, and over any red areas or sores to collect a sample.

The sample may also be collected using a throat washout. For this test, the patient will gargle a small amount of salt water and then spit the fluid into a clean cup. This method gives a larger sample than a throat swab and may make the culture more reliable.

A culture for Streptococcus pyogenes can take 18–24 hours when grown at 37 degrees Celsius (body temperature). [1]

See also

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Group A streptococcal infection human disease

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Scarlet fever Infectious disease

Scarlet fever is a disease resulting from a group A streptococcus infection, also known as Streptococcus pyogenes. The signs and symptoms include a sore throat, fever, headaches, swollen lymph nodes, and a characteristic rash. The rash is red and feels like sandpaper and the tongue may be red and bumpy. It most commonly affects children between five and 15 years of age.

Streptococcal pharyngitis human disease

Streptococcal pharyngitis, also known as strep throat, is an infection of the back of the throat including the tonsils caused by group A streptococcus (GAS). Common symptoms include fever, sore throat, red tonsils, and enlarged lymph nodes in the neck. A headache, and nausea or vomiting may also occur. Some develop a sandpaper-like rash which is known as scarlet fever. Symptoms typically begin one to three days after exposure and last seven to ten days.

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Pharyngitis is inflammation of the back of the throat, known as the pharynx. It typically results in a sore throat and fever. Other symptoms may include a runny nose, cough, headache, difficulty swallowing, swollen lymph nodes, and a hoarse voice. Symptoms usually last 3–5 days. Complications can include sinusitis and acute otitis media. Pharyngitis is a type of upper respiratory tract infection.

Rheumatic fever Post-streptococcal inflammatory disease

Rheumatic fever (RF) is an inflammatory disease that can involve the heart, joints, skin, and brain. The disease typically develops two to four weeks after a streptococcal throat infection. Signs and symptoms include fever, multiple painful joints, involuntary muscle movements, and occasionally a characteristic non-itchy rash known as erythema marginatum. The heart is involved in about half of the cases. Damage to the heart valves, known as rheumatic heart disease (RHD), usually occurs after repeated attacks but can sometimes occur after one. The damaged valves may result in heart failure, atrial fibrillation and infection of the valves.

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Rapid strep test test for strep throat

The rapid strep test (RST) is a rapid antigen detection test (RADT) that is widely used in clinics to assist in the diagnosis of bacterial pharyngitis caused by group A streptococci (GAS), sometimes termed strep throat. There are currently several types of rapid strep test in use, each employing a distinct technology. However, they all work by detecting the presence of GAS in the throat of a person by responding to GAS-specific antigens on a throat swab.

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References

  1. 1 2 3 4 Regoli M, Chiappini E, Bonsignori F, Galli L, de Martino M (January 2011). "Update on the management of acute pharyngitis in children". Ital J Pediatr. 37: 10. doi:10.1186/1824-7288-37-10. PMC   3042010 . PMID   21281502.