Question

4. Identify the pathophysiologic stages of pneumococcal pneumonia (IN ORDER OF DEVELOPMENT) a. Massive dilation of capillaries with alveolar filling with organisms, neutrophils, and fibrin b. Exudate becomes lysed and processed by macrophages, and normal lung tissue is restoring c. Outpouring of fluid into alveoli that supports microorganism growth and spread d. Blood flow decreases, and leukocytes and fibrin consolidate in affected lung tissue.

Answer 1

b : RESOLUTION : Exudate becomes lysed and processed by macrophages, and normal lung tissue is restoring.

Explanation:

Alveolar macrophage is the predominant immune cell which responds to lower airway bacteria. However, a stronger immune response comes into play when an overwhelming virulent pathogen or a large inoculum causes these alveolar macrophages to recruit polymorphonuclear neutrophils(PMN) to phagocytose and engulf these bacteria. The alveolar macrophages release cytokines namely, tumor necrosis factor-alpha and interleukins. Interleukin-8 and granulocyte colony-stimulating factor promotes neutrophil chemotaxis and maturation. The leakage of the alveolar-capillary membrane due to cytokines can lead to a decrease in compliance and hence, dyspnea. Cytokines such as IL-1 and TNF can lead to constitutional symptoms such as fever. Bacterial pneumonia is a result of this inflammatory response. These cytokines are essential for the immunity but, the excess can lead to sepsis and multiorgan failure. The body tries to balance the deleterious effects of cytokines by attenuation of several inflammatory mechanisms by IL-10.