Overview
Definition:
Recurrent strep pharyngitis refers to multiple episodes of Group A Streptococcus (GAS) pharyngitis within a defined period, raising questions about the source of infection: true reinfection or persistent carriage of GAS
This is a common diagnostic challenge in pediatric practice.
Epidemiology:
GAS pharyngitis is most common in children aged 5-15 years
Recurrence rates vary, with studies suggesting significant proportions of children experiencing multiple episodes annually
Factors such as household contacts, school settings, and hygiene practices influence incidence.
Clinical Significance:
Accurate differentiation is crucial to avoid unnecessary antibiotic use, which can lead to resistance and side effects
Identifying true reinfection is important for family screening and implementing effective prevention strategies, while recognizing carriage avoids over-treatment of asymptomatic individuals.
Clinical Presentation
Symptoms:
Typical symptoms include sudden onset of sore throat, fever, headache, abdominal pain, nausea, vomiting, and tonsillar exudates
Scarlet fever rash may be present
Recurrent cases may present with similar acute symptoms or milder, less distinct symptoms.
Signs:
Physical examination may reveal erythematous pharynx and tonsils with exudates, palatal petechiae, anterior cervical lymphadenopathy, and a scarlatiniform rash
Absence of cough and coryza are characteristic of GAS pharyngitis
Signs in recurrent cases may be less pronounced with repeated exposures.
Diagnostic Criteria:
The diagnosis of GAS pharyngitis relies on clinical criteria (e.g., Centor score) combined with laboratory confirmation
A modified Centor score (McIsaac score) includes age as a factor
Definitive diagnosis requires a positive throat culture or rapid antigen detection test (RADT) for GAS.
Diagnostic Approach
History Taking:
Detailed history is key
Ask about the frequency and timing of previous sore throats, antibiotic use, symptoms of each episode, and exposure history (sick contacts, family history of rheumatic fever or recurrent pharyngitis)
Inquire about adherence to antibiotic treatment for previous episodes.
Physical Examination:
Perform a thorough examination focusing on the pharynx, tonsils, and cervical lymph nodes
Look for exudates, erythema, petechiae, and lymphadenopathy
Assess for any rash suggestive of scarlet fever
Examine other systems to rule out alternative causes of sore throat.
Investigations:
Throat swab for GAS culture is the gold standard
Rapid antigen detection tests (RADTs) offer quicker results but have lower sensitivity, requiring confirmatory culture if negative in symptomatic individuals
Nucleic acid amplification tests (NAATs) offer high sensitivity and specificity
Serological tests (e.g., ASO titer) are useful for diagnosing recent infection or complications but not for acute diagnosis.
Differential Diagnosis:
Consider viral pharyngitis (adenovirus, enterovirus, Epstein-Barr virus), other bacterial pharyngitis (e.g., Arcanobacterium haemolyticum), irritant-induced pharyngitis, allergic pharyngitis, and peritonsillar abscess
In recurrent cases, consider immune deficiencies or anatomical abnormalities affecting the tonsils.
Distinguishing Carrier State Vs Reinfection
Carrier State Definition:
A carrier state is defined as the presence of GAS in the pharynx without symptoms of active infection
Carriers can shed GAS but are not usually the source of new infections in themselves or close contacts, unless they have a significant contact with a susceptible individual or develop a new infection.
Reinfection Definition:
Reinfection implies acquisition of a new GAS strain from an external source, leading to a new symptomatic episode of pharyngitis
This can occur even after treatment, especially in environments with high GAS prevalence
Genetic typing of GAS strains can help differentiate between relapse and reinfection.
Clinical Clues:
Lack of typical acute pharyngitis symptoms, such as fever and exudates, in a child with recurrent positive GAS tests suggests carriage
Conversely, distinct acute symptoms, fever, and response to appropriate antibiotic therapy in a child with a history of positive tests suggest reinfection
The temporal association with sick contacts also aids differentiation.
Laboratory Confirmation:
While initial diagnosis relies on RADT or culture, differentiating requires careful interpretation
Repeated positive tests in asymptomatic children strongly suggest carriage
If a child develops symptoms after prior negative tests, and GAS is detected, reinfection is likely
Advanced molecular typing of GAS strains is the most definitive method but is not routinely available.
Management
Management Of Acute Episode:
Treatment of confirmed GAS pharyngitis is with antibiotics
Penicillin V or amoxicillin are first-line
For penicillin-allergic patients, macrolides (azithromycin, erythromycin) or clindamycin are alternatives
Treatment duration is typically 10 days for penicillin V/amoxicillin, and 5 days for azithromycin.
Management Of Carrier State:
Asymptomatic carriers typically do not require antibiotic treatment unless they are identified as a source of outbreaks or if there is a concern for rheumatic fever risk in close contacts
Treatment of carriers is controversial and should be reserved for specific situations, such as household outbreaks or when there is a family history of acute rheumatic fever.
Management Of Reinfection:
Suspected reinfection should be managed with a full course of appropriate antibiotics
It is crucial to ensure adherence to treatment and to investigate potential sources of reinfection, such as household members or school contacts, who may also be carriers or have undiagnosed pharyngitis.
Family Screening And Treatment:
Consider screening and treating close contacts (household members) if recurrent pharyngitis is a significant problem, especially in cases of suspected reinfection or if there is a history of rheumatic fever
This helps break the chain of transmission
However, routine screening of asymptomatic contacts is not recommended.
Complications
Acute Complications:
Immediate complications of GAS pharyngitis include peritonsillar abscess, cervical lymphadenitis, sinusitis, otitis media, scarlet fever, and acute rheumatic fever (ARF).
Late Complications:
Long-term sequelae primarily include acute rheumatic fever and its subsequent chronic valvular heart disease
Post-streptococcal glomerulonephritis (PSGN) can also occur, though it is less directly related to pharyngeal carriage and more to nephritogenic strains.
Prevention Strategies:
Good hand hygiene, avoiding close contact with infected individuals, and prompt diagnosis and treatment of acute strep pharyngitis are key prevention strategies
Educating families on symptom recognition and adherence to antibiotics is vital
For recurrent cases, considering family screening may be beneficial in specific contexts.
Key Points
Exam Focus:
Differentiating asymptomatic GAS carriage from true symptomatic reinfection is a frequent exam question
Understand the diagnostic criteria for GAS pharyngitis and the nuances of managing recurrent episodes, including when to treat carriers.
Clinical Pearls:
Always confirm GAS with laboratory testing, especially in recurrent cases, before initiating or repeating antibiotic courses
If a child has multiple positive GAS tests but remains asymptomatic, consider carriage and focus on family education and hygiene
Reinfection is strongly suspected with recurrent symptomatic episodes despite appropriate treatment.
Common Mistakes:
Treating asymptomatic carriers without clear indication is a common mistake
Over-reliance on RADTs without confirmatory cultures in symptomatic children can lead to missed diagnoses
Failure to consider family contacts as a source of reinfection or carriage can perpetuate recurrent episodes.