Pneumonia
Introduction.
Pneumonia is a serious lung infection that has multiple causes, such as
viruses and bacteria. Among the more common causes are Mycobacterium,
Chlamydophila, Mycoplasma, Streptococcus, Staphylococcus, Klebsiella and viruses. In immunocompromised individuals,
Pneumocystic carinii, a fungus, is a frequent cause of pneumonia. Symptoms can be mild or severe, leading
to edema and inability to do gas exchange. In severe cases, patients literally
drown in their own body fluids.
Summary
Cause: Streptococcus pneumoniae
- Microscopy: Gram-positive diplococci
- Transmission: Airborne
- Symptoms:
- Complications:
- Pathogenesis: capsule resists phagocytosis
- Treatment: Penicillin
Cause: Staphylococcus aureus
- Microscopy: Gram-positive staphylococci
- Transmission: Aspiration; hematogenous spread
- Symptoms: infiltrates; abscesses
- Complications: necrotizing pneumonia (MRSA)
- Pathogenesis: cytotoxins
- Treatment: Vancomycin
Cause: Rhodococcus equi
- Microscopy: Gram-positive coccobacillus
- Transmission: Airborne (dust)
- Symptoms: lung granulomas (immunocompromised)
- Complications: bacteremia and cavitation
- Pathogenesis: survive in macrophage; death of macrophage, recruit
phagocytes
- Treatment: Combination therapy (fluoroquinolones, rifampin,
aminoglycosides, erythromycin)
Cause: Klebsiella pneumoniae
- Microscopy: Gram-negative rods
- Transmission: Moisture droplets, respirator biofilm
- Symptoms: cough, bloody sputum, cavitation
- Complications: necrotizing pneumonia; CRKP
- Pathogenesis: capsule avoids phagocytosis
- Treatment: antibiotics as indicated by sensitivity tests
Cause: Pseudomonas aeruginosa
- Microscopy: Gram-negative rods
- Transmission: Aspiration
- Symptoms: mild to severe; necrosis of lung tissue
- Complications: necrotizing pneumonia (70% mortality)
- Pathogenesis: MDR; opportunistic pathogen; colonize
immunocompromised patients (cystic fibrosis)
- Treatment: combination of several antibiotics
Cause: Chlamydophila pneumoniae
- Microscopy: Gram-negative obligate intracellular pathogen, very
small
- Transmission: Airborne
- Symptoms: mild (bronchitis) to severe (pneumonia); cough, malaise
- Complications: atherosclerosis
- Pathogenesis: Intracellular growth in epithelial cells,
macrophages, vascular smooth muscle; inflammation
- Treatment: macrolides, tetracyclines
Cause: Mycoplasma pneumoniae
- Microscopy: Cell-wall-less (Gram-negative) pleomorphic
- Transmission: Airborne
- Symptoms: fever, malaise, headache, cough
- Complications: primary atypical pneumonia
- Pathogenesis: Damage of ciliated respiratory epithelium; adhesion
- Treatment: Erythromycin, tetracycline
Pneumocystis pneumonia
- Cause: Pneumocystis jirovecii
- Microscopy: Cysts (~ 5 um) in lung tissue and sputum
- Transmission: Airborne
- Symptoms: Fever, pneumonitis
- Complications: Asphyxiation, systemic spread, particularly in AIDS
- Pathogenesis: Host inflammatory response
- Treatment: Trimethoprim - sulfamethoxasole
Summary
- Cause:
- Microscopy:
- Transmission:
- Symptoms:
- Complications:
- Pathogenesis:
- Treatment: