« Huntington's Disease | Main | Obesity »

Strep Throat

The group A streptococcus bacterium (Streptococcus pyogenes) is responsible for most cases of streptococcal illness. Other types (B, C, D, and G) may also cause infection. Group B streptococci cause most streptococcal infections in newborns and maternal post-labor/delivery infections.

Signs and Symptoms of Strep Throat

The signs and symptoms of strep throat are red, sore throat with white patches on tonsils, swollen lymph nodes in neck, fever, and headache. Nausea, vomiting, and abdominal pain are more common in children. The patient will usually not have a cough, unlike in a viral infection.

Transmission of Strep Throat

The illness is caused by the bacterium Streptococcus pyogenes and is spread by direct, close contact with patients via respiratory droplets (coughing or sneezing). Casual contact rarely results in transmission. Rarely, contaminated food, especially milk and milk products, can result in outbreaks. Untreated patients are most infectious for 2-3 weeks after onset of infection. Incubation period, the period after exposure and before symptoms show up, is 2-4 days. Patient is no longer infectious within 24 hours of commencing treatment.


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. If the rapid test is negative, a follow-up culture (which takes 24 to 48 h) may be performed. A negative culture suggests a viral infection, in which case antibiotic treatment should be withheld or discontinued.

In the UK, rapid strep testing is not available to general practitioners and a clinical decision must be made whether to treat, whilst awaiting upto 7 days for a swab result to be reported. This is criticized for encouraging overuse of antibiotics (see antibiotic resistance).

Treatment of Strep Throat

Antibiotic treatment will reduce symptoms, minimize transmission, and reduce the likelihood of complications. Treatment consists of penicillin (oral drug for 10 days; or 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 complete the full course of antibiotics to prevent complications.

Amoxicillin should be avoided for treatment of a sore throat if bacterial (swab)confirmation has not been obtained as it causes a distinctive rash should the true illness prove to be Glandular fever.

Superficial streptococcal skin infections

Scarlet fever (Scarlatina)

Scarlet fever is a streptococcal infection that occurs most often in association with a sore throat and rarely with impetigo or other streptococcal infections. It is characterized by sore throat, fever and a rash over the upper body that may spread to cover almost the entire body.

Signs and Symptoms of Scarlet Fever

Persons with scarlet fever have a characteristic rash that is fine, red, rough-textured and blanches upon pressure. Scarlet fever also produces a bright red tongue with "strawberry" appearance. The skin often "desquamates," or peels, after recovery, usually on tips of fingers and toes.

Transmission of Scarlet Fever

The illness is spread by the same means as strep throat.


Other than the occurrence of the rash, the treatment and course of scarlet fever are no different from those of any strep throat.

Change in virulence Read any novel of the 18th century and Scarlet Fever often seems to be followed by many months in convalescense institutions. Most children now are ill for under a week. Whilst this is used as an example of the benefits of antibiotics, it is also true that the bacterial mutated in the early-mid 20th century into less virulent forms. The term Scarlatina is used to describe the modern milder disease.

Impetigo is a superficial skin infection most common among children age 2-6 years. Skin infections are usually caused by different streptococci strains than those that cause strep throat. It can also be caused by Staphylococcus infection.

Signs and Symptoms of streptococcal skin infection

One or more pimple-like lesion surrounded by reddened skin. Lesions fill with pus, then break down over 4-6 days and form a thick crust. Impetigo is often associated with insect bites, cuts, and other forms of trauma to the skin. Itching is common. Scratching may spread the lesions.


The infection is spread by direct contact with lesions or with nasal carriers. The incubation period is 1-3 days. Dried streptococci in the air are not infectious to intact skin.


The diagnosis is made based on the typical appearance of the skin lesion.

Treatment of streptococcal skin infection

Topical or oral antibiotics are usually prescribed.


This illness results in inflammation of skin and underlying tissues.

Signs and Symptoms of Cellulitis

The skin is painful, red, and tender. Patients experience fever and chills. Lymph nodes may be swollen. The skin may blister and then scab over. Perianal cellulitis may also occur with itching and painful bowel movements. The erysipelas rash may occur on face, arms, or legs and has raised borders. The infection may recur, causing chronic swelling of extremities (lymphadenitis). Transmission

Cellulitis begins with minor trauma, such as a bruise, usually to an extremity.


The organism may be cultured from skin lesions or recovered from blood. Treatment

Depending on the severity, treatment involves either oral or intravenous antibiotics.

Severe streptococcal infections

Some strains of group A streptococci (GAS) cause severe infection. Those at greatest risk include children with chickenpox; persons with suppressed immune systems; burn victims; elderly persons with cellulitis, diabetes, blood vessel disease, or cancer; and persons taking steroid treatments or chemotherapy. Intravenous drug users also are at high risk. Severe GAS disease may also occur in healthy persons with no known risk factors. All severe GAS infections may lead to shock, multisystem organ failure, and death. Early recognition and treatment are critical. Diagnostic tests include blood counts and urinalysis as well as cultures of blood or fluid from a wound site. Antibiotics of choice include penicillin, erythromycin, and clindamycin.


An invasion of bacteria into the bloodstream. Once in the bloodstream, the infection can spread to other parts of body, producing abscesses, peritonitis (inflammation of abdominal cavity), endocarditis (inflammation of the heart), or meningitis. Bacteremia may lead to sepsis or shock, causing a systemic illness with high fever, blood coagulation (thickening) and eventually organ failure.

Focal infections with or without bacteremia

GAS can cause focal infections, which are limited to a particular site. These include pneumonia, abscess of tissues near the tonsils, joint infections (septic arthritis), bone infections (osteomyelitis), peritonitis, and meningitis. Bacteremia can be associated with these infections, but it is not always present. Treatment depends on the specific clinical findings.

Toxic shock syndrome

Streptococcal toxic shock syndrome begins with flu-like symptoms (fever, chills, and muscle aches). Pain is common, usually in an extremity, sometimes in the abdomen or chest. The condition progresses to confusion and coma. Blood pressure drops, kidneys malfunction, and soft tissues may be infected. The source of streptococcus, when identified, is most often the site of a minor wound or bruise. The syndrome occurs most often in healthy adults between the ages of 20-50. Leaving a tampon inside the vagina for long periods of time can also cause Toxic shock syndrome.

Complications of group A streptococcal infections

Acute rheumatic fever (ARF) is a complication of a strep throat caused by particular strains of GAS. Although common in developing countries, ARF is rare in the United States, with small isolated outbreaks reported only occasionally. It is most common among children between 5-15 years of age. A family history of ARF may predispose an individual to the disease. Symptoms typically occur 18 days after an untreated strep throat. An acute attack lasts approximately 3 months. The most common clinical finding is a migratory arthritis involving multiple joints. The most serious complication is carditis, or heart inflammation (rheumatic heart disease), as this may lead to chronic heart disease and disability or death years after an attack. Less common findings include bumps or nodules under the skin (usually over the spine or other bony areas) and a red expanding rash on the trunk and extremities that recurs over weeks to months. Because of the different ways ARF presents itself, the disease may be difficult to diagnose. A neurological disorder, chorea, can occur months after an initial attack, causing jerky involuntary movements, muscle weakness, slurred speech, and personality changes. Initial episodes of ARF as well as recurrences can be prevented by treatment with appropriate antibiotics.

Post streptococcal glomerulonephritis (PSGN) is an uncommon complication of either a strep throat or a streptococcal skin infection. Symptoms of PSGN develop within 10 days following a strep throat or 3 weeks following a GAS skin infection. PSGN involves inflammation of the kidney. Symptoms include pale skin, lethargy, loss of appetite, headache and dull back pain. Clinical findings may include dark-colored urine, swelling of different parts of the body (edema), and high blood pressure. Treatment of PSGN consists of supportive care.

Posted by Staff at May 14, 2005 10:56 PM

blog comments powered by Disqus

Comments Archive

My 23 year old daughter was diagnosed with strep throat three days ago. She was prescribed the Z-pack antibiotics (5). Tonight she has a bluish red coloring on her colar bone. It does not hurt when she touches it. Ten days ago, she was prescribed by her oral surgeon Amoxilyn, after the removal of her four wisdom teeth. I wonder what this weird bluish skin means. Could these broken blood vessels as a result of so much strong antibiotics back to back?
Concerned mother.

Posted by: Giselle Di Santis at January 15, 2007 6:44 AM

hey i love your website i am a bactira freak

Posted by: brandon lopez at January 16, 2007 7:11 PM