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What is a rapid strep test?
The rapid strep test is a quick and accurate diagnostic tool used to determine whether or not strep bacteria are present in the patient's throat. The same test may be used to evaluate for the presence of Streptococci in other infected areas (for example, perianal infection in either gender, or vulvar infection in pre-pubertal girls).
Streptococcal throat infections facts
- The incidence of sore throats (pharyngitis) varies with season, age of the patient, and geographic area.
- Sore throats can be caused by infection from either viruses or bacteria.
- Less than one-third of all sore throats is bacterial, the most common bacteria being Group A streptococcus (GAS).
- Children 5 years to 15 years of age are the most common age group infected by group A strep.
- Infection is most common during the winter/early spring season. This is likely due in part to the seasonal variation of strep bacteria concentration in the community as well as the higher likelihood of close proximity of individuals due to either weather conditions and/or school attendance during winter months.
The pediatric population may have different strep throat (GAS) symptoms:
- Infants (< 1 year of age) low grade fever (< 101 F, 38 C), thick purulent nasal discharge 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
- 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. Other upper respiratory symptoms such as runny nose and cough are not usually associated with strep throat.
The majority of sore throats (70% to 85%) are caused by viruses. Representative examples are:
- EBV (Epstein-Barr virus or mononucleosis) and CMV (cytomegalic inclusion virus) infections may produce a mononucleosis symptom complex (sore throat, fever, disproportionate fatigue, tender and swollen neck lymph nodes, and commonly enlargement of the spleen and liver);
- adenovirus (which may be associated with conjunctivitis ("pink eye");
- influenza; and
- miscellaneous others - herpes, rhinovirus (cause of the common "cold"), etc.
Unfortunately, no single characteristic element of either the patient's history or physical examination discriminates between strep thraot (GAS) and non-strep sore throat. As a result, it is imperative to have laboratory evaluation since strep throat should be treated with antibiotics, while relief of symptoms remains the mainstay of treatment for viral sore throats.
Why is identification of streptococcal infection important?
Patients benefit both immediately and potentially in the long-term by rapid confirmation of streptococcal cause of their sore throat. Antibiotic treatment provides a quicker reduction of symptoms, shortens the duration of illness and quickly, and efficiently eliminates the possibility of spread of infection to others.
- Although rare, serious consequences of streptococcal infections do occur. Rheumatic fever is associated with heart, joint and nervous system damage and is preventable by rapid treatment of strep disease.
- Serious kidney disease that may result in kidney failure may also be a consequence of streptococcal infection.
- A throat infection due to strep needs antibiotic therapy initiated as rapidly as possible. The rapid strep test facilitates this goal.
What is the traditional test for strep throat?
The traditional test for a strep throat has been a throat culture. The major drawback of a throat culture is that the results take two to three days due to the time necessary to allow enough GAS bacteria to grow to enable accurate identification.
Why is the rapid test better?
By comparison with culture methods, a rapid strep test is much quicker and can produce results within minutes.
How is a rapid strep test done?
Obtaining a specimen is the same whether your doctor will do a throat culture or rapid test for strep. 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). It is important to avoid contact with other structures inside the mouth such as the tongue or cheeks. The swab is then placed in a specialized container and the rapid test performed. Many people find that obtaining the swab produces a gagging sensation. However, since the entire swabbing process lasts less than five seconds this inconvenience is minimal.
What are the limitations of the rapid strep test?
There are several manufactures of rapid strep tests. Each manufacturer has designed their test to respond only to the presence of the particular streptococcal bacteria (Group A) responsible for strep throat. Other bacteria which are less much less likely to cause sore throats are not identified by the rapid strep test.
- The test will not detect viral causes of sore throat.
- A positive test response occurs when a reaction occurs between a protein on the surface of strep bacteria and chemicals in the test materials. Either living or dead strep bacteria will produce a positive reaction.
- Most rapid strep tests have a sensitivity of 95%, meaning that the test will be positive in 95 of 100 patients who are documented to have strep throat via throat culture obtained at the same time. 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.
- A positive culture requires antibiotics.
- The rapid strep test has a 98% specificity. This means that 98 of 100 positive tests correctly indicate the presence specifically of Group A streptococcus bacteria; 2 of 100 positive results are "false positives" - indicative of similarities between various surface proteins found on strep bacteria and other non-strep bacteria found in the mouth.
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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.
The Red Book - 29th Edition 2012 Report of the Committee on Infectious Diseases. American Academy of Pediatrics; pg: 668 - 675.
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Aches, Pain, FeverAlthough a fever technically is any body temperature above the normal of 98.6 F (37 C), in practice, a person is usually not considered to have a significant fever until the temperature is above 100.4 F (38 C). Fever is part of the body's own disease-fighting arsenal; rising body temperatures apparently are capable of killing off many disease-producing organisms.
Adenoids and Tonsils
Tonsillitis is a contagious infection with symptoms of bad breath, snoring, congestion, headache, hoarseness, laryngitis, and coughing up blood.
Tonsillitis can be caused acute infection of the tonsils, and several types of bacteria or viruses (for example, strep throat or mononucleosis). There are two types of tonsillitis, acute and chronic. Acute tonsillitis lasts from one to two weeks while chronic tonsillitis can last from months to years.
Treatment of tonsillitis and adenoids include antibiotics, over-the-counter medications, and home remedies to relieve pain and inflammation, for example, salt water gargle, slippery elm throat lozenges, sipping warm beverages and eating frozen foods (ice cream, popsicles), serrapeptase, papain, and andrographism Some people with chronic tonsillitis may need surgery (tonsillectomy or adenoidectomy ).
Common ColdThe common cold (viral upper respiratory tract infection) is a contagious illness that may be caused by various viruses. Symptoms include a stuffy nose, headache, cough, sore throat, and maybe a fever. Antibiotics have no effect upon the common cold, and there is no evidence that zinc and vitamin C are effective treatments.
Enlarged SpleenAn enlarged spleen or splenomegaly, is generally caused by other diseases or conditions such as infections, cancers, blood disorders, or decreased blood flow. Symptoms of an enlarged spleen are often unnoticed. A feeling of fullness after eating a small amount of food and not being able to eat large meals may be a symptom of an enlarged spleen. Treatment for an enlarged spleen depends upon the cause.
Is Strep Throat ContagiousStrep throat is caused by group A streptococcus bacterium. Symptoms of strep throat are:
- sore throat,
- white patches or spots on the tonsils,
- headache, and
- nausea and vomiting.
Liver (Anatomy and Function)The liver is the largest gland and organ in the body. There are a variety of liver diseases caused by liver inflammation, scarring of the liver, infection of the liver, gallstones, cancer, toxins, genetic diseases, and blood flow problems. Symptoms of liver disease generally do not occur until the liver disease is advanced. Some symptoms of liver disease include jaundice, nausea and vomiting, easy bruising, bleeding excessively, fatigue, weakness, weight loss, shortness of breath, leg swelling, impotence, and confusion. Treatment of diseases of the liver depend upon the cause.
Sore Throat (Pharyngitis)
Sore throat usually is described as pain or discomfort in the throat area. A sore throat may be caused by bacterial infections, viral infections, toxins, irritants, trauma, or injury to the throat area. Common symptoms of a sore throat include a fever, cough, runny nose, hoarseness, earaches, sneezing, and body aches. Home remedies for a sore throat include warm soothing liquids and throat lozenges. OTC remedies for a sore throat include OTC pain relievers such as ibuprofen or acetaminophen. Antibiotics may be necessary for some cases of sore throat.
Sore Throat SlideshowExplore the types and causes of a sore throat through pictures, including strep throat, and learn how to find relief from that raw, scratchy feeling.
Strep Throat QuizTake the Strep (Streptococcal) Throat Infection Quiz to learn about causes, symptoms, treatments, prevention methods, diagnosis, and complications of this common infectious disease.
Strep Throat (GAS)
Strep throat is a bacterial infection of the throat. Signs and symptoms of strep throat include headache, nausea, vomiting, sore throat, and fever.
Strep throat symptoms in infants and children are different than in adults. Strep throat is contagious and is generally passed from person-to-person. Treatment for strep throat symptoms include home remedies and OTC medication; however, the only cure for strep throat are antibiotics.
Strep Throat PictureStrep infection often produces a distinct pattern of white patches in the throat and on the tonsils, as well as red swollen tonsils. See a picture of Step Throat and learn more about the health topic.
Swollen Ankles and Swollen Feet
Swollen ankles and swollen feet is a symptom of an underlying disease or condition such as edema, medications, pregnancy, injuries, diseases, infections, lymphedema, or blood clots. Symptoms associated with swelling of the ankles and feet include:
- Skin that is easily indented when pressed down with a finger that slowly returns to its more puffy state when the finger pressure is removed.
- Generalized swelling of the feet or ankles.
- Indentations marks in the skin of the feet or ankles left by socks or shoes
- The skin associated with the swelling is slightly pale, and the indentation marks are slightly darker than the surrounding swollen tissue.
Treatment for swollen ankles or feet depends upon the cause, and soothing symptoms.
Upper Respiratory Infection
An upper respiratory infection is a contagious infection of the structures of the upper respiratory tract, which includes the sinuses, nasal passages, pharynx, and larynx. Common causes of an upper respiratory infection include bacteria and viruses such as rhinoviruses, group A streptococci, influenza, respiratory syncytial, whooping cough, diphtheria, and Epstein-Barre. Examples of symptoms of upper respiratory infection include:
- Sore throat
- Nasal congestion
Treatment of upper respiratory infections are based upon the cause. Generally, viral infections are treated symptomatically with over-the-counter (OTC) medication and home remedies.