Strep throat

Strep throat

File:PHIL 3183 lores.jpg Strep throat
ICD-10	J02.0
ICD-O:	{{{ICDO}}}
ICD-9	034.0
OMIM	{{{OMIM}}}
MedlinePlus	{{{MedlinePlus}}}
eMedicine	{{{eMedicineSubj}}}/{{{eMedicineTopic}}}
DiseasesDB	{{{DiseasesDB}}}

Strep throat, also known as Streptococcal pharyngitis or Streptococcal sore throat is a contagious infection of the mucous membranes of the pharynx caused by group A Streptococcus bacteria. It primarly affects children and those with weakened immune systems and is responsible for about ten percent of all sore throats.

If strep throat is not treated, it can develop into rheumatic fever or other serious conditions.

Overview

Streptococcus pyogenes is a form of Streptococcus bacteria that is the primary causative agent in Group A streptococcal infections (GAS), including strep throat, acute rheumatic fever, scarlet fever, acute glomerulonephritis and necrotizing fasciitis. Infections are largely categorized by the location of infection, such as the pharynx in the case of strep throat, the upper body in the case of scarlet fever, and the skin and underlying tissues in the case of impetigo. Some other diseases that can be caused by the Group A streptococcus bacterium or other causal agents include pneumonia (pulmonary alveolus) and tonsillitis (tonsils).

Streptococcus pyogenes is a Gram-positive coccus that grows in long chains depending on the culture method (Ryan and Ray 2004). Other Streptococcus species may also possess the Group A antigen, but human infections by non-S. pyogenes GAS strains (some S. dysgalactiae subsp. equisimilis and S. anginosus Group strains) appear to be uncommon.

Strep throat is variously reported as responsible for five to ten percent of all sore throats (Longe 2006) or ten to fifteen percent of all sore throats (Longe 2005). Most sore throats are associated with viral infections such as influenza or the common cold (Longe 2006).

Strep throat it primarly affects children, particularly those betwen the ages of 5 and 15 (Longe 2005). Others who are particular susceptible include those whose immune systems are weakened by stress or other infections, as well as smokers or live in damp, crowded conditions (Longe 2005; Longe 2006).

Strep throat is a contagious disease, spreading from person to person via by direct, close contact with an infected person via respiratory droplets (cough or sneezing). Rarely, food by coughing or sneezing, especially milk and milk products, can result in outbreaks.

Untreated patients are most infectious for 2-3 weeks after onset of infection. The incubation period, the period after exposure and before symptoms show up, is difficult to establish as some people do not become symptomatic. However, it is thought to be between two and five days.

Rheumatic fever is particularly tied to incidents of strep throat. Rheumatic fever is an inflammatory disease that may develop after a Group A streptococcal infection (such as strep throat or scarlet fever) and can involve the heart, joints, skin, and brain. It typically arises in children as a complication of strep throat that has been untreated or inadequately treated (Longe 2006). Rheumatic fever is often characterized by arthritis (inflammation of the joints) and/or carditis (inflammation of the heart), although other symptoms may be present.

Since children are particularly vulnerable to strep throat, then most are susceptible to rheumatic fever (Longe 2006). Strep throat is easily treated by a ten-day course of antibiotics. However, when infection occurs without symptoms or when the medication is not taken for the full ten days, the individual has a 3 percent chance of developing rheumatic fever (Longe 2006). Rheumatic fever occurs approximately 20 days after strep throat or scarlet fever. In up to a third of cases, the underlying strep infection may not have caused any symptoms.

Symptoms and diagnosis

Symptoms of strep throat include:

Sore throat

Red and white patches in the throat

Difficulty swallowing

Tender cervical lymphadenopathy

Red and enlarged tonsils

Halitosis

Fever of 101 F/38C or greater

Rash

Frequent cold chills

Absence of cough

Diagnosis

Signs and symptoms

A study of 729 patients with pharyngitis in which 17% had a positive throat culture for group A streptococcus, identified the following four best predictors of streptococcus:

1. Lack of cough

• sensitivity = 56%
• specificity = 74%

2. Swollen tender anterior cervical nodes

• sensitivity = 80%
• specificity = 55%

3. (Marked) tonsillar exudates. Although the original study did not specify the degree of exudate, 'marked exudate' may be more accurate. A subsequent study of 693 patients with 9.7% having positive cultures found that 'marked exudates' had a sensitivity and specificity of 21% and 70% while 'pinpoint exudates' were nonspecific with sensitivity and specificity of 22% and 45%.

• sensitivity = 65%
• specificity = 69%

4. History of fever

• sensitivity = 78%
• specificity = 45%

When these findings are counted in a patient, the probabilities of positive cultures in the original study (prevalence=17%) are:

• 4 findings -> 55.7%
• 3 findings -> 30.1 – 34.1%
• 2 findings -> 14.1 – 16.6%
• 1 findings -> 6.0 - 6.9%
• 0 findings -> 2.5%

The probabilities can also be computed with the following equation: X = −2.69 + 1.04 (exudtons) + 1 (swolacn) - 0.95 (cough) + 0.89 (fevhist)

Tests

The throat of the patient is swabbed for culture or for a rapid strep test (5 to 10 min) which can be done in the doctor's office. A rapid test tests for the presence of antibodies against the bacteria. If the rapid test is negative, a follow-up culture (which takes 24 to 48 hours) may be performed. A negative culture suggests a viral infection, in which case antibiotic treatment should be withheld or discontinued.

Treatment

Antibiotic treatment will reduce symptoms slightly, minimize transmission, and reduce the likelihood of complications. Treatment consists of penicillin (orally for 10 days; or a single intramuscular injection of penicillin G). Erythromycin is recommended for penicillin-allergic patients. Second-line antibiotics include amoxicillin, clindamycin, and oral cephalosporins. Although symptoms subside within 4 days even without treatment, it is very important to start treatment within 10 days of onset of symptoms, and to complete the full course of antibiotics to prevent rheumatic fever, a rare but serious complication. Other complications that can occur include an ear infection, sinus infection, acute glomerulonephritis, or an abscess on the tonsils (peritonsillar abscess).

According to a meta-analysis in Pediatrics, the overall summary odds ratio (OR) for the bacteriologic cure rate significantly favored cephalosporins compared with penicillin (OR: 3.02; 95% confidence interval [CI]: 2.49 –3.67, with the individual cephalosporins [cephalexin, cefadroxil, cefuroxime, cefpodoxime, cefprozil, cefixime, ceftibuten, and cefdinir] showing superior bacteriologic cure rates). The overall summary OR for clinical cure rate was 2.33 (95% CI: 1.84 –2.97), significantly favoring cephalosporins. .

Penicillins should be avoided for treatment of a sore throat if bacterial (swab) confirmation has not been obtained since it causes a distinctive rash if the true illness proves to be viral. This rash is harmless but alarming. The most common virus responsible for strep-like symptoms is glandular fever, also known as mononucleosis. Typically, antibiotics such as clindamycin or clarithromycin will be prescribed if there is any doubt as to whether the infection is bacterial as it does not cause a rash in the presence of a virus.

In addition to taking antibiotics, other ways to relieve strep symptoms include taking nonprescription medications (such as ibuprofen and acetaminophen/paracetamol) for throat pain and fever reduction, and getting plenty of rest. Also, gargling with warm saltwater (1/4 teaspoon of table salt in 8 oz. warm water) can help relieve throat pain as well as warm, plain tea. Avoid orange juice or other citrus drinks. The acids in them may irritate the throat.

Lack of Treatment

The symptoms of strep throat usually improve even without treatment in five days, but the patient is contagious for several weeks. Lack of treatment or incomplete treatment of strep throat can lead to various complications. Some of them may pose serious health risks.

Infectious complications

• The active infection may occur in the throat, skin, and in blood.
• Skin and soft tissues may become infected, resulting in redness, pain, and swelling. Skin and deep tissues may also become necrotic (rare).
• Scarlet fever is caused by toxins released by the bacteria.
• Rarely, some strains may cause a severe illness in which blood pressure is reduced and lung injury and kidney failure may occur (toxic shock syndrome).

Noninfective complications

• During the infection, antibodies (disease–fighting chemicals) are produced. *Rare complication can result after the organism is cleared, when these antibodies cause disease in body organs.
• Rheumatic fever is a heart disease in which the inflammation of heart muscle and scarring of heart valves can occur.
• Glomerulonephritis is a kidney disease in which the injury may lead to kidney failure.

See also

• PANDAS - Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections
• Tonsillitis
• Pharyngitis
• Psoriasis

References

ISBN links support NWE through referral fees

• Longe, J. L. 2005. The Gale Encyclopedia of Alternative Medicine. Farmington Hills, Mich: Thomson/Gale. ISBN 0787693960.
• Longe, J. L. 2006. The Gale Encyclopedia of Medicine. Detroit: Thomson Gale. ISBN 1414403682

<ref name=Sherris>{{cite book | author = Ryan KJ; Ray CG (editors) | title = Sherris Medical Microbiology | edition = 4th ed. | publisher = McGraw Hill | year = 2004 | id = ISBN 0-8385-8529-9

External links

• Group A Streptococcal Infections - National Institute of Allergy and Infectious Diseases.
• Post-infectious glomerulonephritis - mayoclinic.com.

Credits

New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

• Strep_throat  ^history
• Streptococcus  ^history
• Streptococcus_pyogenes  ^history

The history of this article since it was imported to New World Encyclopedia:

• History of "Strep throat"

Note: Some restrictions may apply to use of individual images which are separately licensed.