Strep throat, or streptococcal pharyngitis is caused by bacteria called Group A beta-hemolytic Streptococcus. There are many different virus’ that can cause a sore throat, and viral sore throats are much more common than bacterial causes. If you have cough, congestion, hoarseness, pink eye, or oral ulcers then chances are much higher that you have a virus. It takes approximately 2-5 days after exposure to develop symptoms (incubation period).
Strep throat is typically diagnosed with a throat swab and sometimes even throat culture. A positive strep throat is typically treated with antibiotics. Viral pharyngitis is treated symptomatically.
Some clinicians may use “Modified Centor Criteria” for diagnosis of strep throat. Centor criteria relates to the probability of bacterial pharyngitis vs viral etiology.
Centor Criteria includes
1. Age. If your age is between 3-14 yrs, this adds to the likelihood of strep by 1 point, 15-44 yrs old is 0 points, and if you are older than 44yrs old, this is -1 point. Less than 2 years old is very rare.
2. Exudate or swelling on tonsils. Exudate (pus pockets on tonsils) or swollen tonsils is 1 point.
3. Tender/swollen anterior cervical lymph nodes: 1 point
4. Fever of 100.4 or greater: 1 point
5. Presence of absence of cough. If cough is absent: 1 point.
If you have 1 point the probability of streptococcal pharyngitis is <10%. 2 points is 11-17%. 3 points is 28-35%, and 4 or 5 points is up to 52%.
While strep throat in and of itself is uncomfortable, antibiotic treatment is typically given to prevent abscesses around the tonsils, sinus infections, ear infections, and most importantly rheumatic fever. According to the AAFP, the number needed to treat to prevent 1 case of peritonsillar and retropharyngeal abscesses is 1000. What this means is that out of 1000 known positive cases that are NOT treated with antibiotics, then only 1 patient would develop an abscess. While rheumatic heart disease (RHD) remains the worst possible potential outcome of untreated strep throat, in higher developed countries the number needed to treat is around 20,000 to prevent 1 case of RHD. In developing countries, the incidence of RHD is much higher with number needed to treat at 3,000-4,000. It is much less common to develop RHD as an adult with strep throat, and children remain the higher risk population.
Without antibiotic treatment symptoms may last 7-10 days. Without treatment you have a very small chance to develop the above-mentioned illnesses. With or without treatment with antibiotics for confirmed positive streptococcus pharyngitis does not change the risk of a rare complication called Poststreptococcal glomerulonephritis.
Per CDC, patient may return to school after 12 hours of antibiotic therapy if fevers have resolved, while the AAFP recommends 24 hours before return to school after starting antibiotics.
The best way to prevent getting or spreading strep throat includes:
Cover your mouth and nose when you cough or sneeze, wash your hands or use alcohol-based hand sanitizer often. Wash, and do not share eating or drinking plates, cups, or utensils of infected persons.
Jeff Ure, PA-C