What is the next step in managing a 6-year-old male with erratic behavior, full body aches, and thick green nasal discharge, who recently completed a course of treatment for strep throat (streptococcal pharyngitis)?

Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS)

This 6-year-old requires immediate evaluation for PANDAS, a post-streptococcal autoimmune neuropsychiatric syndrome, with urgent neuropsychiatric assessment, anti-streptococcal antibody titers (ASO, anti-DNase B), and consideration of immunomodulatory therapy if diagnosis is confirmed.

Clinical Recognition

This presentation is highly concerning for PANDAS rather than simple streptococcal pharyngitis complications:

• Acute-onset neuropsychiatric symptoms following documented streptococcal infection (completed treatment course) including erratic behavior, aggression, screaming episodes, and anterograde amnesia are hallmark features of PANDAS 1, 2

• Timeline correlation of 7-10 days post-streptococcal infection with behavioral deterioration fits the typical PANDAS presentation pattern 1

• Age appropriateness: 6-year-old falls within the peak PANDAS age range (prepubertal children, typically 5-15 years) 3

• The thick green nasal discharge and body aches suggest possible concurrent acute bacterial sinusitis, which requires separate evaluation 3

Immediate Diagnostic Workup

Confirm recent streptococcal exposure:

• Obtain anti-streptolysin O (ASO) and anti-DNase B titers to document recent Group A Streptococcal infection, even though throat culture may now be negative 1, 2
• These antibody titers rise 3-6 weeks after acute infection and provide retrospective confirmation 1

Rule out alternative diagnoses:

• Brain MRI to exclude structural lesions, encephalitis, or other CNS pathology 1
• Lumbar puncture if encephalitis is suspected based on fever, altered consciousness, or focal neurological findings 1
• Complete blood count, comprehensive metabolic panel, and inflammatory markers (ESR, CRP) 1

Evaluate concurrent sinusitis:

• The thick green nasal discharge persisting 7-10 days meets criteria for acute bacterial sinusitis (persistent symptoms >10 days without improvement) 3
• Consider CT sinuses if severe symptoms or complications suspected 3

Treatment Algorithm

For Confirmed/Suspected PANDAS:

Antibiotic therapy:

• Re-treat with different antibiotic class since azithromycin was already used and macrolide resistance is significant 4, 5
• Prescribe amoxicillin 50 mg/kg/day divided twice daily for 10 days (maximum 1000 mg/day) as first-line alternative 1, 2
• Alternative: amoxicillin-clavulanate if concurrent sinusitis confirmed (addresses both conditions) 3, 4

Immunomodulatory therapy (specialist consultation required):

• Consider IVIG or plasmapheresis for severe, acute-onset PANDAS cases with significant functional impairment 1
• Corticosteroids may provide benefit in acute severe presentations 1
• These interventions require pediatric neuropsychiatry or immunology consultation 1

For Concurrent Acute Bacterial Sinusitis:

• Amoxicillin with or without clavulanate 45-90 mg/kg/day divided twice daily for 10 days addresses both potential PANDAS and confirmed sinusitis 3
• This dual approach is appropriate given the clinical presentation 3, 4

Critical Pitfalls to Avoid

Do not dismiss as behavioral problem:

• Acute-onset neuropsychiatric symptoms with memory impairment in a previously normal child following streptococcal infection is PANDAS until proven otherwise 1, 2
• Delayed recognition and treatment may worsen long-term neuropsychiatric outcomes 1

Do not assume streptococcal treatment was adequate:

• The child may be a streptococcal carrier with inadequate eradication, requiring alternative antibiotic 3, 4
• Macrolide resistance rates are significant in some U.S. regions (up to 20% resistance to azithromycin) 4, 5

Do not perform routine post-treatment throat culture:

• Throat culture is not indicated unless symptoms persist or recur, as carriers may test positive without active infection 3, 4
• Focus instead on anti-streptococcal antibody titers for PANDAS diagnosis 1, 2

Do not use azithromycin again:

• Treatment failure with macrolides suggests either resistance or carrier state 4, 5
• Switch to beta-lactam antibiotic (amoxicillin or amoxicillin-clavulanate) 2, 4

Specialist Referral

Urgent pediatric neuropsychiatry or neurology consultation is mandatory for:

• Confirmation of PANDAS diagnosis 1
• Consideration of immunomodulatory therapy 1
• Long-term management planning including possible prophylactic antibiotics 1, 2

Pediatric infectious disease consultation if:

• Multiple treatment failures occur 4
• Family members have recurrent streptococcal infections suggesting household transmission 3

Follow-Up Strategy

• Reassess within 48-72 hours after antibiotic initiation to evaluate neuropsychiatric symptom trajectory 1, 5
• Patients with worsening symptoms after appropriate antibiotic initiation require immediate re-evaluation 5
• Document baseline neuropsychiatric symptoms using standardized scales for monitoring treatment response 1
• Consider testing household contacts if recurrent infections occur, treating those with positive cultures 3