MICROBIO - CHAPTER 22

• Streptococcal respiratory diseases


  Pharyngitis, laryngitis, bronchitis, scarlet fever, rheumatic fever, acute glomerulonephritis

  
• Streptococcal respiratory diseases


  • Sore throat, difficulty swallowing, fever, malaise, headache
• Group A streptococci (S. pyogenes)


  Cause streptococcal respiratory diseases
• Streptococcal virulence factors

  • M proteins
  • Hyaluronic acid capsule
  • Streptokinases
  • C5a peptidase
  • Pyrogenic toxins
  • Streptolysins
• Pathogenesis of streptococcal respiratory diseases

  Occurs when normal microbiota are depleted, large inoculum is introduced, or adaptive immunity is impaired
• Epidemiology of streptococcal respiratory diseases

  Spread via respiratory droplets, occur most often in winter and spring

  
• Diagnosis, treatment, and prevention of streptococcal respiratory diseases

  Often confused with viral pharyngitis, oral penicillin is an effective treatment
• Diphtheria


  Sore throat, localized pain, fever, presence of a pseudomembrane that can obstruct airways
• Corynebacterium diphtheriae


  Causes diphtheria, produces diphtheria toxin that prevents polypeptide synthesis and causes cell death
• Pathogenesis and epidemiology of diphtheria

  Spread via respiratory droplets or skin contact, symptomatic in immunocompromised or nonimmune individuals, leading cause of death among unimmunized children
• Diagnosis, treatment, and prevention of diphtheria

  Diagnosis is based on presence of a pseudomembrane, treated with antitoxin and antibiotics, immunization is an effective prevention
• Rhinosinusitis and otitis media


  Malaise accompanied by headache and inflamed nasal passages, severe pain in the ears
• Causes of rhinosinusitis and otitis media

  Various respiratory microbiota, may be due to damage to upper respiratory system and auditory tube
• Pathogenesis and epidemiology of rhinosinusitis and otitis media

  Bacteria in the pharynx spread to the sinuses via the throat, rhinosinusitis is more common in adults, otitis media is more common in children
• Diagnosis, treatment, and prevention of rhinosinusitis and otitis media


  Symptoms are often diagnostic, no known way to prevent rhinosinusitis, flushing nasal and sinus cavities with saline solution can reduce duration of symptoms
• Common cold


  Sneezing, runny nose, congestion, sore throat, malaise, and cough
• Pathogens causing common cold

  Enteroviruses (rhinoviruses) are the most common cause, numerous other viruses can also cause colds
• Pathogenesis of common cold

  Cold viruses replicate in and kill infected cells
• Epidemiology of common cold

  Rhinoviruses are highly infective, spread by coughing/sneezing, fomites, or person-to-person contact, develop some immunity to serotypes over time
• Diagnosis, treatment, and prevention of common cold


  Signs and symptoms are usually diagnostic, pleconaril can reduce duration of symptoms, hand antisepsis is important preventive measure
• Lower respiratory organs are usually axenic
• Bacterial infection of the lower respiratory system can cause life-threatening illness
• Bacterial pneumonias


  Lung inflammation accompanied by fluid-filled alveoli and bronchioles, described by affected region or organism causing the disease
• Bacterial pneumonias are the most serious and the most frequent in adults
• Pneumococcal pneumonia


  Fever, chills, congestion, cough, chest pain, results in short, rapid breathing, blood enters the lungs, causing rust-colored sputum
• Streptococcus pneumoniae


  Causes pneumococcal pneumonia, has virulence factors like adhesins, capsule, and pneumolysin
• Pathogenesis and epidemiology of pneumococcal pneumonia


  Infection occurs by inhalation of bacteria, bacterial replication causes damage to the lungs, host secretory IgA destroyed by secretion of pneumococcal IgA protease, pneumococcal pneumonia account for most cases of bacterial pneumonia
• Diagnosis, treatment, and prevention of pneumococcal pneumonia

  Diagnosed by identifying diplococci in sputum smears, penicillin is drug of choice for treatment, some strains are now penicillin resistant, vaccination is method of prevention
• Primary atypical (mycoplasmal) pneumonia

  Fever, malaise, sore throat, excessive sweating, symptoms may last for weeks
• Mycoplasma pneumoniae


  Causes primary atypical pneumonia, has an adhesion protein as a virulence factor
• Pathogenesis of primary atypical pneumonia

  Bacteria colonize and kill epithelial cells, causes mucus buildup and colonization by other bacteria
• Epidemiology of primary atypical pneumonia

  Bacteria spread by nasal secretions, most common form of pneumonia in teenagers and young adults
• Diagnosis, treatment, and prevention of primary atypical pneumonia


  Difficult to diagnose, treated with erythromycin or doxycycline, prevention difficult since infected individuals may be asymptomatic
• Klebsiella pneumonia


  Pneumonia symptoms with a thick, bloody sputum
• Klebsiella pneumoniae


  Causes Klebsiella pneumonia, has a capsule as a virulence factor
• Pathogenesis and epidemiology of Klebsiella pneumonia

  Immunocompromised individuals at greatest risk for infection
• Diagnosis, treatment, and prevention of Klebsiella pneumonia


  Diagnosed by identifying Klebsiella in sputum samples, treated with antimicrobials, prevention involves good aseptic technique by health care workers
• Other bacterial pneumonias


  • Haemophilus influenzae
  • Staphylococcus aureus
  • Yersinia pestis (pneumonic plague)
  • Chlamydophila psittaci (ornithosis)
  • Chlamydophila pneumoniae
• Legionnaires' disease


  Typical pneumonia symptoms, pulmonary function can rapidly decrease
• Legionella pneumophila


  Most common cause of Legionnaires' disease, kills human cells and causes tissue damage and inflammation