Overview
Definition:
Community-acquired pneumonia (CAP) in children and adolescents is an acute infectious process affecting the lower respiratory tract, acquired outside of healthcare settings
Atypical pneumonia refers to CAP caused by pathogens other than typical bacteria like Streptococcus pneumoniae, often characterized by a more indolent onset and distinct clinical features.
Epidemiology:
Atypical pneumonia accounts for a significant proportion of CAP in children, particularly those aged 5-15 years
Mycoplasma pneumoniae is the most common cause in this age group, followed by Chlamydophila pneumoniae
Legionella pneumophila is rare but can cause severe illness.
Clinical Significance:
Accurate identification and management of atypical pneumonia are crucial in pediatric practice
Delayed or incorrect diagnosis can lead to treatment failures, prolonged illness, and potential complications
Understanding atypical pathogens is essential for DNB and NEET SS examinations.
Clinical Presentation
Symptoms:
Insidious onset of cough, often dry and persistent
Gradual development of fever, which may be low-grade
Malaise and headache are common
Sore throat and rhinitis may precede pulmonary symptoms
Extrapulmonary symptoms like myalgias, rash, and gastrointestinal upset can occur.
Signs:
Physical examination may reveal mild tachypnea and accessory muscle use
Auscultation may show scattered rhonchi or crackles, with diminished breath sounds being less prominent than in typical bacterial pneumonia
Wheezing can be present
Normal or near-normal vital signs are not uncommon, particularly in milder cases.
Diagnostic Criteria:
Diagnosis is primarily clinical, supported by imaging and laboratory investigations
The absence of a response to standard beta-lactam antibiotics for typical bacterial pneumonia, combined with characteristic symptoms and imaging findings, strongly suggests atypical pneumonia
Specific serological tests or PCR can confirm the etiology, but these are often not practical for initial management decisions.
Diagnostic Approach
History Taking:
Elicit detailed history of symptom onset and progression
Inquire about recent sick contacts, travel history, and environmental exposures
Ask about vaccination status
Identify any underlying chronic conditions, such as asthma or immunocompromise, which can alter presentation and management.
Physical Examination:
Perform a thorough respiratory examination, including assessment of respiratory rate, effort, and oxygen saturation
Auscultate lung fields systematically for adventitious sounds
Examine for signs of extrapulmonary involvement, such as rash or pharyngeal erythema.
Investigations:
Chest X-ray typically shows interstitial infiltrates, patchy opacities, or bilateral involvement, which may be less dense than lobar consolidation seen in typical pneumonia
Complete blood count (CBC) may show mild leukocytosis or be normal
Serological tests (IgM/IgG) for Mycoplasma or Chlamydophila pneumoniae can be helpful retrospectively but are not useful for acute management
PCR-based tests are increasingly available and can provide rapid results.
Differential Diagnosis:
Other causes of pediatric pneumonia including viral pneumonia, bacterial pneumonia (e.g., Streptococcus pneumoniae, Haemophilus influenzae), bronchiolitis, and atypical presentations of conditions like asthma exacerbation or foreign body aspiration
Early recognition of the atypical pattern is key.
Management
Initial Management:
Most children with atypical pneumonia can be managed as outpatients, provided they are stable and have adequate home support
Supportive care includes adequate hydration, rest, and antipyretics (e.g., paracetamol, ibuprofen) for fever
Close monitoring for signs of respiratory distress is essential.
Medical Management:
Macrolide antibiotics are the mainstay of treatment for suspected atypical pneumonia
Azithromycin (10-12 mg/kg once daily for 3-5 days) or clarithromycin (7.5-15 mg/kg divided into two doses daily for 7-14 days) are commonly used
Doxycycline (4-5 mg/kg/day divided into two doses, max 200 mg/day) is an alternative for children >8 years old
Duration of therapy is typically 7-14 days
Fluoroquinolones are generally reserved for severe or refractory cases in older adolescents.
Surgical Management:
Surgical intervention is rarely indicated for uncomplicated atypical pneumonia
It may be considered in cases of severe complications such as empyema or lung abscess, but this is uncommon.
Supportive Care:
Ensure adequate fluid intake to prevent dehydration
Monitor oxygen saturation closely
If hospitalized, provide supplemental oxygen as needed
Physical therapy for airway clearance might be considered in select cases
Education of parents regarding home care and warning signs is paramount.
Complications
Early Complications:
Pleural effusion, empyema, lung abscess, acute respiratory distress syndrome (ARDS) are rare but can occur in severe cases
Extrapulmonary manifestations such as rash, arthralgias, pericarditis, myocardi tis, encephalitis, and Stevens-Johnson syndrome have been reported, particularly with Mycoplasma pneumoniae.
Late Complications:
Recurrent pneumonia is uncommon
Post-infectious sequelae like reactive airway disease or persistent cough can occur in some children.
Prevention Strategies:
No specific vaccines are available for common atypical pathogens
Good hygiene practices, including handwashing, can reduce transmission
Prompt diagnosis and appropriate antibiotic therapy are key to preventing complications.
Prognosis
Factors Affecting Prognosis:
Age, underlying health status, timely initiation of appropriate antibiotic therapy, and development of complications influence prognosis
Most children recover fully with appropriate treatment.
Outcomes:
With appropriate macrolide therapy, most children experience rapid clinical improvement within 48-72 hours
Full recovery is typical, with resolution of infiltrates on follow-up imaging occurring over several weeks.
Follow Up:
Follow-up is generally not required for uncomplicated cases
However, children with severe illness, prolonged symptoms, or complications should have clinical follow-up to ensure complete recovery and address any residual issues
Re-evaluation is recommended if symptoms do not improve with treatment.
Key Points
Exam Focus:
Mycoplasma pneumoniae is the most common atypical pathogen in children over 5 years
Macrolides (azithromycin, clarithromycin) are first-line agents
Chest X-ray often shows interstitial infiltrates
Distinguish from typical bacterial pneumonia based on clinical course and antibiotic response.
Clinical Pearls:
Consider atypical pneumonia in children with persistent cough, low-grade fever, and extrapulmonary symptoms, especially when initial treatment with beta-lactams fails
Remember the age predilection for Mycoplasma
Doxycycline is an option for older children (>8 years).
Common Mistakes:
Over-reliance on chest X-ray alone without correlating with clinical findings
Delaying macrolide initiation while waiting for confirmatory serology
Inadequate duration of antibiotic therapy
Misdiagnosing atypical pneumonia as viral bronchitis.