Pathogenesis

Pneumococcal pneumonia develops when encapsulated pneumo-cocci, the virulent form, are inhaled into the alveoli of a suscep-

Pneumococci Polymorphonuclear neutrophils

Pneumococci Polymorphonuclear neutrophils

10 mm

Figure 23.9 Streptococcus pneumoniae Gram stain of sputum from a person with pneumococcal pneumonia showing Gram-positive diplococci and polymorphonuclear neutrophils (PMNs).

10 mm

Figure 23.9 Streptococcus pneumoniae Gram stain of sputum from a person with pneumococcal pneumonia showing Gram-positive diplococci and polymorphonuclear neutrophils (PMNs).

tible host, multiply rapidly, and cause an inflammatory response. The bacteria are resistant to phagocytosis because their capsules interfere with the action of C3b, the fraction of complement responsible for opsonization. Serum and phagocytic cells pour into the air sacs of the lung, causing difficulty breathing. This increase in fluid produces abnormal shadows on chest X-ray films of patients with pneumonia (figure 23.10). Material coughed from the lungs, called sputum, increases in amount and contains pus, blood, and many pneumococci. ■ opsonization by C3b, p. 383

The inflammatory response to the infection often involves nerve endings, causing pain; the condition in which pain arises from an inflamed pleura is called pleurisy. Pneumococci that enter the bloodstream from the inflamed lung are responsible for three often fatal complications: septicemia, a symptomatic infection of the bloodstream; endocarditis, an infection of the heart valves; and meningitis, an infection of the membranes covering the brain and spinal cord. Individuals who do not develop such complications usually develop sufficient specific anticapsular antibodies within about a week to permit phagocytosis and destruction of the infecting organisms. Complete recovery usually results. Most pneumococcal strains do not destroy lung tissue.

Was this article helpful?

0 0
You Are What You Eat

You Are What You Eat

Nutrition is a matter that people spend their careers learning about and requires volumes of books to explain. My objective is to instruct you how to consume a healthy nutritional diet that aids your body in burning off fat instead of storing it. You do not require overwhelming science to get this.

Get My Free Ebook


Post a comment