Streptococcal pharyngitis approach, diagnostic criteria and treatment.
Strep throat, due to Streptoccocus pyogenes in the majority of cases. Other agents can be: S. agalactiae, S. dysgalactiae subsp. equisimilis, S. pneumoniae and the S. mitis spp. group, S. anginosus spp. group, S. bovis spp. group, S. mutans spp. group, S. salivarius spp. group, and a handful of other Streptococci isolated from animals that may occasionally cause human infection.
Most pharyngitis are viral, and the use of antibiotics are overly used, that is why the use of The Modified Centor Criteria (or McIsaac Score) correlate directly with risk of positive throat culture for GAS and the empiric treatment with antibiotic.
In patients with three or more Centor criteria a rapid antigen detection test without backup of throat culture fro negative results.
Throat culture has been considered the gold standard method to establish the microbial cause of acute pharyngitis. However, compared with RADT, cultures delay diagnosis as they take 24 to 48 hours to grow. Throat culture is primarily used as a backup test in patients with negative RADT where clinical concern for GAS or bacterial pharyngitis is still high.
Treatment guideline in the USA:
Penicilin is the first line treatment, cephalosporins, macrolides, and clindamicyn.
Oral penicillin V* (phenoxymethyl penicillin)
500 mg two to three times daily for 10 days
500 mg twice daily for 10 dayS
Intramuscular penicillin, single dose
Penicillin G benzathine (Bicillin L-A) 1.2 million units
500 mg orally twice daily for 10 days25 to 50 mg/kg per day orally in two equally divided doses (maximum 1000 mg per day) for 10 days
For patients with potential severe hypersensitivity to beta-lactam antibiotics (eg, penicillin, cephalosporins):
500 mg orally on day 1 followed by 250 mg orally on days 2 through 512 mg/kg/dose (maximum 500 mg/dose) orally on day 1 followed by 6 mg/kg/dose (maximum 250 mg/dose) orally on days 2 through 5
250 mg orally twice daily for 10 days7.5 mg/kg/dose (maximum 250 mg per dose) orally twice daily for 10 days
300 mg orally three times daily for 10 days
Children and Adolescents:
Oral penicillin V* (phenoxymethyl penicillin)
If ≤27 kg: 250 mg two to three times daily for 10 days
If >27 kg: 500 mg two to three times daily for 10 days
50 mg/kg per day orally (maximum 1000 mg per day) for 10 days. May be administered in two or three equally divided doses.
Intramuscular penicillin, single dose
If ≤27 kg: Penicillin G benzathine and penicillin G procaine (Bicillin C-R 900/300) 600,000 units. Consists of benzathine penicillin G 900,000 units mixed with procaine penicillin G 300,000 units.
If >27 kg: Penicillin G benzathine (Bicillin L-A) 1.2 million units
25 to 50 mg/kg per day orally in two equally divided doses (maximum 1000 mg per day) for 10 days
For patients with potential severe hypersensitivity to beta-lactam antibiotics (eg, penicillin, cephalosporins):
12 mg/kg/dose (maximum 500 mg/dose) orally on day 1 followed by 6 mg/kg/dose (maximum 250 mg/dose) orally on days 2 through 5
7.5 mg/kg/dose (maximum 250 mg per dose) orally twice daily for 10 days
If ≤70 kg: 7 mg/kg/dose (maximum 300 mg per dose) orally three times daily for 10 days
If >70 kg: 300 mg orally three times daily for 10 days
Treatment guideline in Mexico:
Amoxicilin with clavulanic acid 500 mg orally every 8 hours fro 10 days
first generation cephalosporin for 10 days
clindamicyn 600 mg/day in 2-4 dose fro 10 days
Penicillin G procaine 1,200,000UI every 12 hours 2 doses, followed by 3 doses of penecillin G 800,000ui every 12 hours IM.
in case of Penicillin allergy:
Erithromycine 500 mg every 12 hours for 10 days
Cefalexin 250mg every 12 hours or cephadroxil 1 every 12 hrs
tmp/smx 80/400mg 2 pills every 12 hours for 10 days
In case of failure to response to treatment, to erradicate penicillin G is used, 1.200.000UI every 21 day for 3 months
The best way to keep from getting strep throat is to wash your hands often and avoid sharing eating utensils, like forks or cups. It is especially important for anyone with a sore throat to wash their hands often and cover their mouth when coughing and sneezing. There is no vaccine to prevent strep throat.
