Streptococcal pharyngitis
| Streptococcal pharyngitis | |
|---|---|
| Specialty | Otorhinolaryngology, infectious diseases  |
Strep throat (or "Streptococcal pharyngitis", or "Streptococcal sore throat") is a form of Group A streptococcal infection that affects the pharynx.
Symptoms
The signs and symptoms of strep throat are red, sore throat with white patches on tonsils, swollen lymph nodes in the 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 or coldlike symptoms including stuffy noses and sneezing.
Transmission
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.
Diagnosis
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 typical bacterial antigens in the swab, which are detected by specific antibodies provided in the kit. If the rapid test is negative (=normal), 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
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.
Amoxicillin 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 glandular fever, better known as mononucleosis. This rash is harmless but alarming.