Chapter 17

• Respiratory tract infections


  They are infections involving the respiratory tract, classified as upper respiratory tract infections and lower respiratory tract infections
• Upper respiratory tract


  • Nose larynx isinuses
• Lower respiratory tract


  • Bronchial tree and the lungs
• Causative Organisms of Respiratory Tract Infections

  • Viruses
  • Bacteria
  • Fungi
• Risk factors for RTI:

  • Poor environmental standards such as poor housing conditions, overcrowding, and air pollution both inside and outside the home
• Transmission of respiratory tract infections

  1. Direct spread via droplet nuclei (e.g., sneezing, talking, or coughing)

  2. Indirect spread via articles or hands contaminated with infectious secretions
• Acute rhinitis

  A common cold and an illness in both children and adults, with incidence and seasonal occurrence being predictable.
• Etiologic agents of the common cold


  • Rhinovirus (most common)
  • Parainfluenza viruses
  • Respiratory syncytial virus
  • Coronavirus
  • Adenoviruses
  • Enteroviruses
  • Influenza viruses
  • Reoviruses
• Antibiotics have no role in the management of the common cold
• Rhinoviruses


  Non-enveloped RNA viruses that are the main cause of the common cold, with more than 100 serologic types
• Coronaviruses


  Enveloped RNA viruses that are the second most common cause of the common cold, and were implicated as the etiologic agent of SARS (Severe Acute Respiratory Syndrome)
• SARS


  • A severe form of atypical pneumonia characterized by fever, non-productive cough, dyspnea, and hypoxia, with an incubation period ranging from 2 to 10 days
• There is no antiviral therapy or vaccine available for SARS
• Adenoviruses


  Non-enveloped DNA viruses that cause a variety of upper and lower respiratory tract diseases
• Modes of transmission for adenoviruses

  • Aerosol droplet
  • Fecal-oral
  • Direct inoculation of conjunctivae by fingers
• Clinical findings of adenovirus infections

  • Nasopharyngitis
  • Pharyngoconjunctival fever
  • Bronchitis
  • Atypical pneumonia
  • Hemorrhagic cystitis
  • Gastroenteritis
• There is no antiviral therapy for adenovirus infections
• Pharyngitis


  Inflammation of the mucous membranes of the pharynx, including tonsillitis, tonsillopharyngitis, and nasopharyngitis
• Nasopharyngitis


  A common illness of childhood, occurring more commonly during the cold weather months, with adenoviruses, influenza, and parainfluenza viruses as the most common causes
• Tonsillopharyngitis


  Inflammation involving both the pharynx and the tonsils, with Streptococcus pyogenes being the most common cause
• Scarlet fever


  An infection that occurs in association with streptococcal pharyngitis, caused by Streptococcus pyogenes strains producing streptococcal pyrogenic exotoxin
• Sinusitis


  Inflammation of the mucosal lining of one or more of the paranasal sinuses, with Haemophilus influenzae and Streptococcus pneumoniae being the principal pathogens
• Management of sinusitis


  1. Antimicrobial therapy

  2. Normal saline washes

  3. Use of anti-histamines if allergic rhinitis is contributory

  4. Use of corticosteroids to reduce inflammation

  5. Surgical drainage
• Otitis externa


  Inflammation involving the external ear, with Pseudomonas aeruginosa being the more common cause in tropical countries
• Otitis media


  Inflammation of the mucoperiosteal lining of the middle ear, with Streptococcus pneumoniae and Haemophilus influenzae being the most common bacterial causes, and respiratory syncytial virus, influenza virus, adenovirus, and rhinovirus being the common viral causes
• Flushing or irrigation of the external auditory canal

  With 3% hypertonic saline
• Topical corticosteroid cream


  Sufficient if no evidence of infection
• Neosporin cream application


  Three times a day in the presence of overt infection
• Preventive measures


  • Minimizing swimming and exposure to water
  • Minimizing excessive cleaning of the ears
• Otitis media


  Inflammation of the mucoperiosteal lining of the middle ear
• Causes of otitis media

  • Bacteria (Streptococcus pneumoniae, Haemophilus influenzae)
  • Viruses (respiratory syncytial virus, influenza virus, adenovirus, rhinovirus)
• Signs and symptoms of otitis media


  • Fever, irritability, headache, anorexia, vomiting
  • Cough, coryza
  • Otalgia (ear pain)
  • Otorrhea (ear discharge)
  • Hearing impairment
  • Tinnitus (ringing in the ears)
• Complications of otitis media


  • Perforation of the tympanic membrane
  • Mastoiditis
  • Hearing loss
  • Meningitis
  • Brain abscess
• Management of otitis media

  Antibiotics for the specific etiologic agent
• Croup


  Respiratory illness characterized by inspiratory stridor, cough, and hoarseness resulting from obstruction in the region of the larynx
• Causes of croup


  • Parainfluenza viruses
  • Respiratory Syncytial Virus
• Transmission of croup


  Respiratory droplets
• Other respiratory diseases caused by Parainfluenza viruses

  • Common cold
  • Pharyngitis
  • Laryngitis
  • Otitis media
  • Bronchitis
  • Pneumonia
• There is no antiviral drug or vaccine available for croup
• Influenza


  Viral infection that initially involves the upper respiratory tract and later progresses to the lower respiratory tract