Pneumonia Flashcards
How does pneumonia enter the respiratory tract?
Droplets – inhaled into lungs.
Aspiration - unable to protect airways from secretions by glottic closure and coughing.
Bacteremia
Lung antimicrobial peptides
Lysozyme, lactoferrin, defensins, collectins
Lung cells that interact with inhaled microbes
Alveolar macrophages
Dendritic cells
PMNs
NK cells
Virulence factors of microorganisms that cause pneumonia have this in common
They inhibit host defenses in lung like mucus cilia elevator and activity of IgA.
Chlamydophila pneumonia virulence factor
Ciliostatic factor
Mycoplasma pneumoniae virulence factor
Can cut cilia
Influenza lung virulence factor
Reduces tracheal mucus velocity
Strep pneumo virulence factor?
Produces a protease that can split sIgA and has capsule to evade exocytosis
What are factors that increase the inoculum of ingested bacteria?
Gastric dysfunction, gingival or sinus disease, achlorhydria, prolonged critical illness, endotrachial intubation/tracheotomy.
Strep Pneumonia appearance
Gram positive diplococci/chains
Strep pneumonia causes pneumonia what % of the time?
50% of pneumonias that require hospitalizations
Where does strep pneumonia live?
Oropharynx in normal adults.
Staph aureus appearance
Gram positive cocci in clusters
Major settings of staph aureus pneumonia
Secondary complication of respiratory tract infection with influenza.
Hospitalized patient with impaired host defenses
Widespread dissemination through bloodstream.
Hemophilus influenzae appearance
Small gram negative coccobacilli
Often conolize the nasopharynx of normal individuals and lower airways of patients with COPD
Klebsiella pneumonia
Large gram negative bacillus normally found in GI tract. Often seen in the setting of underlying alcoholism
Can cause thick bloody mucoid sputum “currant jelly sputum”
Pseudomonas Aeruginosa
Gram negative bacillus, wide variety of environmental sources
Primarily seen in patients who are debilitated, hospitalized, and often previously treated with antibiotics.
legionella pneumophila
Gram negative bacillus, stains poorly and isn’t seen by usual staining methods. Can affect previously healthy individuals.
Chlamydophila Pneumoniae
Obligate intracellular, not readily cultured. Causes 5-10% of pneumonia.
Mycoplasma pneumoniae
Smallest freeliving organisms
Intermediate between viruses and bacteria (don’t have rigid cell walls, but dont require host machinery to replicate)
Common cause of walking pneumonia. Common in young adults.
Pathology of pneumonia
Infection and inflammation of the distal pulmonary parenchyma. Influx of neutrophils, edema, erythrocytes, mononuclear cells, fibrin.
