II. Epidemiology
- Peak season: Late fall through early spring
- Bimodal peaks in November to December and April to May
-
Prevalence of Streptococcus in peak season
- Child <3 years old: Uncommon
- Child 3-5 years old: Up to 24% have Group A Beta-hemolytic Streptococcus
- Child 5 to 15 years old: Up to 37% have Group A Beta-hemolytic Streptococcus
- Adult: Up to 15% with Pharyngitis have Group A Beta-hemolytic Streptococcus
- Ages affected
- Most commonly affects ages 5 to 12 years old
- Not usually seen in children under age 3
- Incubation: 24 to 72 hours
- Transmission: direct person to person contact
- Passed by Saliva and nasal secretions
- Increased in crowded settings
- May be transmitted with food preparation
- Transmission rate from Streptococcus carriers is 3-11%
-
Infectivity
- Decreases 1-3 days after antibiotic started
-
Return to School and day care recommendations
- Antibiotics for minimum of 24 hours
- No fever
III. Etiology: Streptococcus Pyogenes
IV. Complications
- Non-suppurative
- Suppurative
- Peritonsillar Abscess
- Suppurative Otitis Media
- Cervical Lymphadenitis
- Acute Sinusitis
- Mastoiditis
- Meningitis
- Bacteremia
- Endocarditis
- Pneumonia
V. Symptoms
- Stretococcal exposure in last 2 weeks (Test Sensitivity 19%, Test Specificity 91%)
- Pharyngitis
- Fever (Temperature >100.9)
- Cough absent
- Headache
- Myalgia
VI. Signs
- See Pharyngitis
- Anterior Cervical Lymphadenopathy
- Palatal Petechiae (Test Sensitivity 7%, Test Specificity 95%)
- Pharyngeal exudate (Test Sensitivity 26%, Test Specificity 88%)
VII. Differential Diagnosis
- See Pharyngitis Causes
- Common other causes
- Infectious Mononucleosis
- Posterior cervical adenopathy, Fatigue and prolonged Pharyngitis
- Hand, foot and mouth disease
- Oral Lesions, hand and foot skin lesions
- Infectious Mononucleosis
VIII. Labs
-
Streptococcal Rapid Antigen Test
- Used to distinguish intermediate probability of Streptococcal Pharyngitis (Centor Score 2-3)
- Test Sensitivity: 86%
- Test Specificity: 96%
-
Group A Streptococcal PCR (Point-Of-Care GAS Nucleic Acid Amplification Test)
- Point of Care, 15 minute test for Group A Streptococcus Test via Nucleic Acid Amplification (NAAT)
- More expensive that the Streptococcal Rapid Antigen Test
- However, nearly perfect Test Sensitivity and requires no Throat Culture
- Group A Streptococcal Colonization will also result in a positive PCR test
- Other Bacterial Pharyngitis Causes are not identified by molecular testing
- Efficacy
- Positive Predictive Value: 97.7%
- Negative Predictive Value: 100%
-
Throat Culture
- Used to confirm a negative rapid Antigen test
- IDSA recommends confirmatory Throat Culture in children (higher risk of Strep Throat complications)
- Some authors argue that Throat Culture is unnecessary
- They argue rapid Antigen test is adequately sensative for a very low risk of Rheumatic Fever
- Preventing each case of Rheumatic Fever costs $8 Million in U.S.
- Lean (2014) Pediatrics 134(4):771-81 [PubMed]
- Used to confirm a negative rapid Antigen test
-
Serology
- Consider in complicated cases (e.g. suspected Rheumatic Fever, Poststreptococcal Glomerulonephritis)
- Antistreptolysin O titer (ASO Titer)
- Confirms diagnosis (with serial values), but not helpful in acute disease
- Increases within 1 week of infection and peaks at 4 to 6 weeks after infection
- Anti-Deoxyribonuclease B (anti-DNase B)
- Increases within 1 week of infection and peaks at 6 to 8 weeks after infection
IX. Diagnosis
- See Strep Score
X. Management: Acute Episode
- See Sore Throat symptomatic management
- Prescribe medications in liquid form if odynophagia
- Glucocorticoids are NOT routinely recommended (aside from Peritonsillar Abscess)
- Antibiotic Course
- Penicillin use requires 10 day course
- Five days of alternative antibiotics effective
- Amoxicillin Clavulanate (Augmentin)
- Ceftibuten
- Cefuroxime
- Loracarbef
- Clarithromycin
- Erythromycin estolate
- References
- First Line Antibiotics
- Standard Penicillin Regimen
- Penicillin VK (250 mg/5cc; tablets: 250 mg, 500 mg)
- Dosing: 12.5 mg/kg (25 mg/kg if severe) up to 500 mg bid for 10 days
- Child <9 kg: 125 mg (0.5 tsp) po bid
- Child 10-18 kg: 250 (1 tsp) mg po bid
- Child 19-27 kg: 375 (1.5 tsp) mg po bid
- Adult and child >27 kg: 500 mg orally twice daily for 10 days
- Amoxicillin (250 mg/5cc)
- Penicillin is preferred first line
- Child: 25 mg/kg (up to 500 mg) orally twice daily OR 50 mg/kg (up to 1000 mg) once daily for 10 days
- Child <9 kg: 125 mg (0.5 tsp) po bid
- Child 10-18 kg: 250 (1 tsp) mg po bid
- Child 19-27 kg: 375 (1.5 tsp) mg po bid
- Adult and child >27 kg: 500 mg orally twice daily OR 1000 mg orally daily for 10 days
- Penicillin VK (250 mg/5cc; tablets: 250 mg, 500 mg)
- Macrolide for Penicillin Allergic (2-8% resistance, 30% GI adverse effects)
- Erythromycin Base
- Adult: 500 mg PO q6 hours for 10 days
- Erythromycin Estolate
- Children: 20-40 mg/kg divided every 12 hours
- Erythromycin Ethyl Succinate (EES)
- Children: 40 mg/kg divided bid (up to 1 g/day)
- Adult or child >40 kg: 250 mg qid or 333 mg tid
- Azithromycin (200 mg/tsp; 250 mg tablet)
- Child 12 mg/kg/day up to 500 mg for 5 days
- Adult or child >40 kg: 500 mg daily for 5 days (or 500 mg day 1, then 250 mg qd for 4 days)
- Clarithromycin
- Adults: 250 mg orally twice daily for 10 days
- Children: 7.5 mg/kg/dose orally twice daily for 10 days
- Erythromycin Base
- Clindamycin for penicillin Hypersensitivity
- Child: 7 mg/kg/dose orally every 8 hours (up to 300 mg/dose) for 10 days
- Adult: 300 mg orally every 8 hours for 10 days
- Single IM dose regimen (Consider for non-compliant)
- Benzathine Penicillin (Bicillin LA)
- Adults (over 27 kg) 1.2 MU IM
- Pediatric (under 27kg): 600,000 U IM
- Benzathine Penicillin (Bicillin LA)
- Standard Penicillin Regimen
XI. Management: Second-Line Antibiotics
- Indications
- Allergy to other other agents
- Recurrent Streptococcal Pharyngitis
- Cephalosporins have higher rates of clinical cure
- Casey (2004) Pediatrics 113:866-82 [PubMed]
-
Cephalexin (Keflex)
- Adult: 500 mg PO bid
- Child: 40 mg/kg/day (up to 1000 mg/day) divided bid
-
Cefadroxil (Duricef)
- Adult: 1 gram orally daily
- Child: 30 mg/kg/day divided bid
-
Cefuroxime (Zinacef, Ceftin)
- Adult: 250 mg PO bid
- Child: 10 mg/kg/dose PO bid
-
Cefpodoxime (Vantin)
- Adult: 100 mg PO bid
- Child: 5 mg/kg/dose PO bid
-
Cefdinir (Omnicef)
- Adult: 300 mg orally twice daily OR 600 mg orally once daily
- Child: 7 mg/kg/dose orally twice daily OR 14 mg/kg/dose once daily
-
Loracarbef (Lorabid)
- Adult: 200-400mg PO bid
- Child: 15 mg/kg/day divided bid
-
Amoxicillin Clavulanate (Augmentin)
- Adult: 500-875 mg PO bid
- Child: 40 mg/kg/day divided bid
- Bicillin
- Single IM shot (dosing as above)
XII. Management: Tonsillectomy
XIII. Efficacy: Benefits of Antibiotic Treatment
- Benefits are at the expense of 10 million antibiotic prescriptions annually for Strep Throat
- Risk of serious Allergic Reaction and Diarrheal illness including Clostridium difficile
- Prevents Rheumatic Fever
- Antibiotics decrease Rheumatic FeverIncidence by 90%
- Effective if given in first 9 days of infection
- Number Needed to Treat: 3000-4000 patients treated to prevent one case Rheumatic Fever
- Data is based on 1940s data, and some estimates estimate NNT at over 1 Million
- One third of those Rheumatic Fever patients develop cardiac complications (NNT 12000)
- No case reports in U.S. of Rheumatic Fever since 1961
- Antibiotics decrease Rheumatic FeverIncidence by 90%
- Prevents suppurative complications
- Peritonsillar Abscess (variable evidence, NNT 50 to 225)
- Acute Sinusitis
- Suppurative Otitis Media (NNT 1 in 200)
- Cervical Lymphadenitis
- Decreases epidemic spread
- Decreases duration of disease by about 1 day
- Does NOT prevent Post-Streptococcal Glomerulonephritis (PSGN)
- References
XIV. Complications
- See Group A Beta-hemolytic Streptococcus
- Lemierre Syndrome
- Airway Compromise
XV. Complications: Etiologies for recurrent Streptococcal Pharyngitis
- Poor Compliance with oral medications (most common)
- Day 3: 50% stopped antibiotics
- Day 6: 70% stopped antibiotics
- Day 9: 80% stopped antibiotics
- Families reporting taking all the medication: 80%
- Repeat exposure in crowded conditions
- School
- Daycare
- Home or workplace
- Eradicated protective throat flora by prior antibiotic
- a-hemolytic Streptococcus is protective normal flora
- Cephalosporins apparently do less harm
- Selected beta-lactam resistance by prior antibiotic
- Consider Augmentin for 10 day course
- Suppressed Immune response from prior antibiotics
-
Antibiotic Resistance
- Penicillin resistance is infrequent in Strep Throat
-
Macrolide (Erythromycin, Biaxin, Zithromax)
- Resistance 2-8% in U.S.
-
Chronic Pharyngeal Carriage of Streptococcus pyogenes
- Pharyngitis due to another cause
XVI. References
- Anderson (2019) Crit Dec Emerg Med 33(9): 3-10
- Bisno (1997) Clin Infect Dis 25:574-83 [PubMed]
- Choby (2009) Am Fam Physician 79(5): 383-90 [PubMed]
- Ebell (2000) JAMA 284(22):2912-8 [PubMed]
- Hayes (2001) Am Fam Physician 63(8):1557-64 [PubMed]
- Kalra (2016) Am Fam Physician 94(1): 24-31 [PubMed]
- Pichichero (1995) Ann Emerg Med 25:390-403 [PubMed]
- Pichichero (1998) Pediatr Rev 19:291-302 [PubMed]
- Smith (2023) Am Fam Physician 107(1): 35-41 [PubMed]
- Van Driel (2021) Cochrane Database Syst Rev (3): CD004406 +PMID: 27614728 [PubMed]