Respiratory Tract Infections

Common URTIs - Sniffles & Soreness

• Common Cold (Viral Rhinitis):
  • Etiology: Rhinovirus (MC), Adenovirus, RSV.
  • Sx: Rhinorrhea, nasal congestion, sore throat, cough.
  • Tx: Symptomatic relief (fluids, rest).
• Acute Otitis Media (AOM):
  • Etiology: Streptococcus pneumoniae (MC), Haemophilus influenzae (non-typable), Moraxella catarrhalis. 📌 SHiM.
  • Sx: Otalgia, fever, irritability, red bulging Tympanic Membrane (TM).
  • Tx: Analgesia. Amoxicillin (80-90 mg/kg/d) if severe/bilateral <2y/otorrhea.

  ⭐ Most common bacterial cause of Acute Otitis Media is Streptococcus pneumoniae.

• Pharyngitis/Tonsillitis:
  • Etiology: Viral (MC). Bacterial: Group A Streptococcus (GAS) - S. pyogenes.
  • Sx: Sore throat, fever. Tonsillar exudates, palatal petechiae (GAS). Modified Centor criteria.
  • Tx: Symptomatic (viral); Penicillin/Amoxicillin (GAS) to prevent Rheumatic Fever.
• Acute Bacterial Rhinosinusitis (ABRS):
  • Sx: Persistent nasal discharge/cough >10 days without improvement, OR severe (fever ≥39°C, purulent discharge) for ≥3 days, OR worsening symptoms.
  • Etiology: S. pneumoniae, H. influenzae.
  • Tx: Amoxicillin.

Acute Airway Obstruction - Alarming Breaths

Stridor, distress, voice change. Rapid assessment vital.

• Epiglottitis (Supraglottitis):

  • Rapid onset, toxic, high fever. 📌 4 D's: Drooling, Dysphagia, Distress, Dysphonia (muffled). Tripod position.
  • X-ray: Thumbprint sign (lateral neck).
  • Mgmt: Secure airway (OR!), IV Ceftriaxone. Avoid agitation.

  ⭐ Epiglottitis classically presents with 'tripod position', drooling, dysphagia, and distress (the 4 D's).

• Croup (Laryngotracheobronchitis):

  • Viral (Parainfluenza). Barking cough, hoarseness, inspiratory stridor.
  • X-ray: Steeple sign (AP neck).
  • Mgmt: Dexamethasone; nebulized Epinephrine (moderate-severe).

• Foreign Body Aspiration (FBA):

  • Sudden choking/gagging Hx. Unilateral wheeze/↓air entry.
  • X-ray: May show object, unilateral hyperinflation/atelectasis.
  • Mgmt: Rigid bronchoscopy.

• Bacterial Tracheitis:

  • S. aureus (often post-viral). Toxic, high fever, purulent secretions.
  • Mgmt: Airway support, IV antibiotics. Poor response to croup Rx.

Lower Respiratory Infections - Deeper Lung Troubles

Bronchiolitis

• Acute viral inflammation of bronchioles; primarily affects infants < 2 years (peak 2-6 months).
• Etiology: Respiratory Syncytial Virus (RSV) most common; also Parainfluenza, Adenovirus.

  ⭐ RSV is the leading cause of bronchiolitis, typically affecting infants <2 years old, with peak incidence at 2-6 months.

• Clinical: Coryza, cough, expiratory wheeze, tachypnea, retractions. Apnea in young infants.
• Diagnosis: Clinical. CXR (not routine): hyperinflation, peribronchial thickening.
• Management: Supportive (O2 for SpO2 < 90-92%), hydration. Palivizumab prophylaxis for high-risk.

Pneumonia

• Infection of lung parenchyma.
• Etiology (Community-Acquired):
  • Neonates: Group B Strep, E. coli.
  • Infants/Young Children: Viruses (RSV), S. pneumoniae.
  • Older Children: Mycoplasma pneumoniae, S. pneumoniae.
• Clinical: Fever, cough, tachypnea (WHO: <2m: >60/min; 2-12m: >50/min; 1-5y: >40/min 📌 Mnemonic: 60-50-40), crackles, ↓air entry.
• Diagnosis: Clinical; CXR shows infiltrates/consolidation.
• Management: Amoxicillin (first-line for typical bacterial CAP). Supportive care.

Specific Chronic/Recurrent Infections - Lingering Lung Woes

• Pertussis (Whooping Cough)

  • Agent: Bordetella pertussis.
  • Stages: Catarrhal (highly contagious, URI sx), Paroxysmal (inspiratory "whoop", post-tussive emesis, lymphocytosis), Convalescent.
  • Dx: PCR (NP swab), culture.
  • Rx: Macrolides (e.g., Azithromycin).
  • Prevention: DTaP/Tdap vaccine.
  • Complications: Apnea (infants), pneumonia, seizures.

  ⭐ Characteristic 'whooping' cough and marked lymphocytosis are key features of the paroxysmal stage of Pertussis.

• Pediatric Tuberculosis (TB)

  • Agent: Mycobacterium tuberculosis.
  • Sx: Persistent cough >2 wks, fever >2 wks, weight loss/failure to thrive.
  • Dx:
    • TST (Mantoux): Induration ≥5 mm (HIV/close contact), ≥10 mm (<4yrs/high risk/chronic illness), ≥15 mm (>4yrs/low risk).
    • IGRA, CXR (hilar adenopathy), AFB smear/culture (gastric aspirate/sputum), NAAT.
  • Rx: Standard Anti-Tubercular Therapy (ATT).
  • Prevention: BCG vaccine (prevents severe forms).

High‑Yield Points - ⚡ Biggest Takeaways

• Bronchiolitis (<2 yrs) is mainly by RSV; treatment is supportive.
• Croup presents with barking cough & stridor; Parainfluenza virus is the usual cause.
• Epiglottitis (often Hib) shows drooling, dysphagia, distress; it's an emergency.
• Pertussis (B. pertussis) has a paroxysmal cough and inspiratory "whoop".
• S. pneumoniae is the top cause of typical bacterial pneumonia in children.
• Mycoplasma pneumoniae causes atypical pneumonia, especially in older children.