Lower Respiratory Tract Infections

Bronchiolitis - Wheezy Baby Blues

• Etiology: RSV (primary); also rhinovirus, metapneumovirus.
• Age: Infants <2 years; peak 3-6 months.
• Clinical: Initial coryza, cough, fever. Progresses to tachypnea (RR >60-70/min), wheeze, retractions, nasal flaring, grunting. Apnea in young/preterm. Poor feeding.
• Diagnosis: Clinical. SpO2 vital. CXR (not routine, severe/atypical): hyperinflation, peribronchial thickening, atelectasis.
• Management: Supportive care.
  • Key interventions: Oxygen (maintain SpO2 >90-92%), hydration (oral/IV/NG), nasal suctioning.
  • Avoid routine bronchodilators, corticosteroids, antibiotics.

• Prevention: Palivizumab (RSV mAb) for high-risk (preterm <29wks, CLD, signif. CHD).

  ⭐ RSV is the most common cause of bronchiolitis and hospitalization in infants <1 year.

Pediatric Pneumonia - Little Lung Attack

⭐ Tachypnea is the most sensitive and specific clinical sign of childhood pneumonia according to WHO.

• Etiology (Age-dependent):
  • Neonates (<1mo): Bacterial (GBS, E. coli).
  • 1-3mo: Atypical (C. trachomatis), Viral (RSV), Bacterial (S. pneumoniae).
  • 3mo-5yr: Bacterial (S. pneumoniae), Viral (RSV, other common viruses).

  • 5yr: Atypical (Mycoplasma pneumoniae), Bacterial (S. pneumoniae).

• Clinical: Fever, cough, tachypnea (key!), retractions, crackles.
• WHO Tachypnea Rates: <2mo: ≥60/min; 2-12mo: ≥50/min; 1-5yr: ≥40/min.
• CXR: May show lobar consolidation, bronchopneumonia, or interstitial infiltrates.
• Mgmt: Supportive (O2, hydration). Outpatient CAP: Amoxicillin (high dose for typical). Atypical suspected: Macrolide.

Pertussis - Whoop There It Is!

• Etiology: Bordetella pertussis (Gram-negative coccobacillus).
• Clinical: Inspiratory 'whoop', post-tussive emesis, apnea (especially in infants). 📌 Pertussis: Paroxysms, Post-tussive emesis, PCR, Prevention (vaccine).
• Stages of Pertussis:

  Stage	Duration	Key Features
  Catarrhal	1-2 weeks	URI symptoms (rhinorrhea, malaise, mild cough)
  Paroxysmal	2-8 weeks	Intense coughing fits ('paroxysms'), inspiratory 'whoop', post-tussive emesis. > ⭐ Marked lymphocytosis is characteristic.
  Convalescent	Weeks-months	Gradual resolution of cough.

• Diagnosis: PCR or culture from nasopharyngeal swab.
• Management: Macrolides (e.g., Azithromycin) for patient & close contacts. Supportive care (oxygen, hydration).
• Prevention: Vaccination (DTaP for children, Tdap for adolescents/adults).

Childhood Pulmonary TB - Tiny Tubercle Trouble

• Etiology: M. tuberculosis.
• Primary Complex: Ghon focus + hilar lymphadenopathy (LND).
• Clinical: Persistent cough (>2 wks), fever (>2 wks), weight loss, contact Hx.
• Diagnosis:
  • TST (Induration: ≥10mm; ≥5mm if HIV+/immunocompromised/malnourished), IGRA.
  • CXR: Hilar LND (most common), consolidation, miliary pattern.
  • CBNAAT (gastric aspirate/sputum).
• Management: ATT 📌 (HRZE regimen). E.g., 2HRZE + 4HR.

⭐ Hilar lymphadenopathy is the most common radiological hallmark of primary pulmonary tuberculosis in children.

Diagnostic Flow (NTEP based):

High‑Yield Points - ⚡ Biggest Takeaways

• Bronchiolitis: Most commonly RSV; management is primarily supportive. Palivizumab for high-risk infants.
• Pneumonia: Streptococcus pneumoniae is the leading bacterial cause. Viral etiologies are very common in younger children.
• Afebrile pneumonia in infants (2 weeks to 3 months): Suspect Chlamydia trachomatis; presents with staccato cough and eosinophilia.
• Mycoplasma pneumoniae: A key cause of atypical pneumonia in older children/adolescents; often with extrapulmonary manifestations.
• Pertussis (Whooping Cough): Caused by Bordetella pertussis; characterized by paroxysmal cough, inspiratory "whoop", and significant lymphocytosis.
• Foreign Body Aspiration: Consider in cases of sudden onset cough/choking, unilateral wheeze, or localised decreased air entry. Rigid bronchoscopy is diagnostic and therapeutic.
• Tuberculosis: Must be considered in endemic settings with prolonged cough, fever, and weight loss; Mantoux test and CXR are initial investigations.