Mouth
Group A Streptococcal Pharyngitis
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Group A Streptococcal Pharyngitis
, Streptococcal Pharyngitis, Strep Throat, Strep Pharyngitis
See Also
Pharyngitis
Pharyngitis Causes
Dysphagia
Tonsillitis
Peritonsillar Abscess
Retropharyngeal Abscess
Lemierre Syndrome
Diphtheria
Chronic Pharyngeal Carriage of Streptococcus pyogenes
Tonsillectomy Indications
Epidemiology
Peak season: Late fall through early spring
Bimodal peaks in November to December and
Apri
l 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
Etiology
Streptococcus Pyogenes
Group A Beta-hemolytic Streptococcus
Complications
Non-suppurative
Rheumatic Fever
Acute post-streptococcal glomerulonephritis
Suppurative
Peritonsillar Abscess
Suppurative
Otitis Media
Cervical
Lymphadenitis
Acute Sinusitis
Mastoiditis
Meningitis
Bacteremia
Endocarditis
Pneumonia
Symptoms
Stretococcal exposure in last 2 weeks (
Test Sensitivity
19%,
Test Specificity
91%)
Pharyngitis
Fever
(
Temperature
>100.9)
Cough
absent
Headache
Myalgia
Signs
See
Pharyngitis
Anterior Cervical Lymphadenopathy
Palatal
Petechiae
(
Test Sensitivity
7%,
Test Specificity
95%)
Pharyngeal exudate (
Test Sensitivity
26%,
Test Specificity
88%)
Differential Diagnosis
See
Pharyngitis Causes
Common other causes
Infectious Mononucleosis
Posterior cervical adenopathy,
Fatigue
and prolonged
Pharyngitis
Hand, foot and mouth disease
Oral Lesion
s, hand and foot skin lesions
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
Bacteria
l
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]
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
Diagnosis
See
Strep Score
Management
Acute Episode
See
Sore Throat
symptomatic management
Prescribe medications in liquid form if odynophagia
Glucocorticoid
s 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
Adam (2000) Clin Infect Dis 182:509-16 [PubMed]
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
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
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
Management
Second-Line Antibiotics
Indications
Allergy to other other agents
Recurrent Streptococcal Pharyngitis
Cephalosporin
s 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)
Management
Tonsillectomy
See
Tonsillectomy Indications
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
Diarrhea
l illness including
Clostridium difficile
Prevents
Rheumatic Fever
Antibiotics decrease
Rheumatic Fever
Incidence
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
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
Del Mar (2006) Cochrane Database Syst Rev (4): CD000023 [PubMed]
Complications
See
Group A Beta-hemolytic Streptococcus
Lemierre Syndrome
Airway Compromise
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
Cephalosporin
s 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
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]
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