What to do for a 3-year-old girl with a persistent cough (over 2 months) that's worsening, recent onset of vomiting, no signs of dehydration, up-to-date with vaccinations, negative strep (streptococcal), COVID-19 (coronavirus disease 2019), and RSV (respiratory syncytial virus) swabs, and a negative chest X-ray (CXR)?

Management of Chronic Cough with Post-Tussive Vomiting in a 3-Year-Old

Given the 2-month duration of worsening cough with post-tussive vomiting in this 3-year-old, you should strongly suspect pertussis and immediately order pertussis-specific testing (PCR or serology depending on symptom duration), while simultaneously initiating a 2-week trial of antibiotics targeting common respiratory bacteria if the cough is wet/productive. 1, 2

Immediate Diagnostic Approach

Pertussis Testing is Critical

• Post-tussive vomiting is a classic "cough pointer" for pertussis, even with up-to-date vaccination status, as vaccine immunity wanes over time 1
• The CHEST guidelines specifically recommend testing for Bordetella pertussis when clinically suspected based on contact history, post-tussive vomiting, or whoop 1
• The appropriate test depends on cough duration: PCR if <3 weeks of symptoms, serology if >3 weeks 1
• At 2 months of cough, serology for pertussis antibodies is the most appropriate test 1

Assess Cough Characteristics

• Determine if the cough is wet/productive versus dry, as this fundamentally changes your diagnostic pathway 1, 2
• Wet cough suggests protracted bacterial bronchitis (PBB), which requires antibiotic treatment 2
• Dry cough may suggest asthma or other etiologies requiring different management 1

Additional Baseline Testing

• While a chest radiograph has already been performed and is negative, this is appropriate as it's recommended for all children with chronic cough >4 weeks 1, 2
• Spirometry is not feasible at age 3, as children typically cannot reliably perform this test until age 6 years 1

Treatment Algorithm Based on Cough Type

If Wet/Productive Cough:

• Prescribe a 2-week course of antibiotics targeting Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis 2
• Appropriate choices include amoxicillin-clavulanate at 90 mg/kg/day divided twice daily 2
• If cough persists after 2 weeks, prescribe an additional 2-week course 2
• This approach treats presumed protracted bacterial bronchitis and may prevent progression to bronchiectasis 2

If Dry Cough:

• Consider an empirical trial of asthma therapy ONLY if other features consistent with asthma are present (history of wheeze, exertional symptoms, atopy) 1
• The CHEST guidelines explicitly recommend against empirical treatment for asthma, GERD, or upper airway cough syndrome unless specific features of these conditions are present 1

Pertussis-Specific Management

If Pertussis Testing is Positive:

• Initiate macrolide antibiotic therapy (azithromycin 10 mg/kg on day 1, then 5 mg/kg daily for days 2-5) 3
• Notify public health authorities for contact tracing 1
• Educate family that antibiotics reduce transmission but may not significantly shorten cough duration if started >3 weeks into illness 1

Environmental and Supportive Measures

• Assess for tobacco smoke exposure, which can exacerbate chronic cough 2
• Ensure adequate hydration and nutrition given the vomiting episodes 3
• Provide antipyretics if fever develops (acetaminophen 10-15 mg/kg every 4-6 hours, maximum 5 doses per 24 hours) 3

Red Flags Requiring Escalation

Watch for development of:

• Respiratory distress (increased work of breathing, retractions, grunting) 2, 3
• Hypoxia (oxygen saturation <92%) 3
• Signs of dehydration despite no current signs 3
• Fever ≥39°C 2
• Any "specific cough pointers" such as digital clubbing, chest deformity, or failure to thrive 2

Follow-Up Plan

• Review the child in 48-72 hours if not improving or if deteriorating 3
• If cough persists beyond 4 weeks of appropriate antibiotic therapy for wet cough, refer to pediatric pulmonology for further evaluation 1
• Repeat chest radiograph only if clinical status changes or new symptoms develop 1

Key Clinical Pitfall to Avoid

Do not dismiss this as "post-viral cough" given the 2-month duration and worsening pattern with post-tussive vomiting. The CHEST guidelines emphasize that chronic cough in children may indicate serious underlying conditions requiring systematic evaluation, and the shorter 4-week timeframe for defining chronic cough exists specifically to prevent missing important diagnoses 1