Pneumonia

Sami Al-Farsi

Introduction

Community-Acquired Pneumonia

Definition: Fever and acute respiratory symptoms and signs, plus parenchymal infiltrate on chest X-ray in a previously healthy child due to a community-acquired infection
Risk factors for increased incidence and severity: prematurity, malnutrition, low socioeconomic status, passive exposure to smoke, daycare attendance, overcrowding, previous pneumonia or wheeze

Etiology

Age is a good predictor of the likely causative agent
In neonates < 3 weeks, pneumonia is usually due to maternally acquired infection
In young infants, consider Chlamydia trachomatis: afebrile, nontoxic, dry cough, peripheral eosinophilia
Consider pertussis especially if immunizations are not current
In children > 5 yrs and adolescents, Streptococcus pneumoniae is the most common cause followed by Mycoplasma pneumoniae and Chlamydia pneumoniae (TWAR)
Other bacterial causes especially in ill infants and toddlers are Staphylococcus aureus, Streptococcus pyogenes, Haemophilus influenzae, and Moraxella catarrhalis

Clinical Presentation

Fever, difficulty breathing, and > 1 of the following: tachypnea, cough, nasal flaring, retractions, crackles, decreased breath sounds
May also present with lethargy, poor feeding, or localized pain to chest or abdomen
Fever, tachypnea, and intercostal retractions are more reliable than auscultation in diagnosing pneumonia in children
Tachypnea (RR > 50 breaths/min) is the most sensitive indicator of pneumonia in infants
Wheeze and hyperinflation suggest viral cause in younger children, and Mycoplasma in older children
In older children, a history of difficulty breathing is more helpful in identifying pneumonia than actual retractions
Older children may present with classic signs such as dullness to percussion, crackles, bronchial breath sounds, increased tactile fremitus

Presentations

Typical: Fever, chills, pleuritic chest pain, and productive cough
Atypical: Gradual onset over several days to weeks, dominated by symptoms of headache and malaise, nonproductive cough, and low-grade fever

Investigations

Assessment of oxygenation is a good indication of severity of disease
Increased WBC with left shift may indicate bacterial cause
CRP and ESR do not distinguish between bacterial and viral and are not routinely recommended
Blood cultures are recommended in all hospitalized patients
Blood cultures only positive in 10-30% of cases
Nasopharyngeal aspirate (NPA) for viral antigen detection is not routinely recommended
Cultures for mycoplasmas, and chlamydia are not routinely recommended
Adolescents and some older children may be able to produce sputum for Gram stain