Pneumonia Pathophysiology

Pneumonia is an inflammation or inflammation in the lung parenchyma are usually caused by infectious agents.

Pneumonia can be caused by various etiologies such as:
1. Bacteria: staphylococcus, streptococcus, aeruginosa, Enterobacter
2. Virus: influenza virus, adenovirus
3. Micoplasma pneumonia
4. Fungi: Candida albicans
5. Aspiration: gastric

Most of pneumonia acquired through aspiration of infective particles. There are several mechanisms that normally protect the lungs from infection. Infectious particles filtered in the nose, or trapped and cleared by mucus and ciliated epithelium in the airways. If a particle can reach the lungs, these particles will be faced with alveoler macrophages, and also with systemic immune mechanisms, and humoral. Infants in the first months of life also has acquired maternal antibodies that can passively protect them from pneumococcal and other infectious organisms. Changes to this protective mechanism may cause the child susceptible to pneumonia, for example in congenital anatomical abnormalities, congenital or acquired immune deficiency, or a neurological disorder that allows the child has aspirations and changes in the quality of mucus secretion or airway epithelium. In children without these predisposing factors, infectious particles can reach the lung through changes in the defense of the normal anatomical and physiological. This most often occurs due to viral upper respiratory tract. The virus can spread to the lower respiratory tract and cause pneumonia virus.

Alternatively, the damage caused by viruses of the normal defense mechanisms may lead to bacterial pathogens infect the lower airway. These bacteria can be an organism that normally colonizes the upper respiratory tract or the bacterium is transmitted from one person to another through droplet spread in the air. Sometimes bacterial and viral pneumonia (eg varisella, measles, rubella, CMV, Epstein-Barr virus, herpes simplex virus) can occur through either hematogenous dissemination from localized sources or bacteremia / viremia generalisata.2
After reaching the lung parenchyma, the bacteria causing an acute inflammatory response that includes fluid exudation, fibrin deposits and infiltration of polymorphonuclear leukocytes in alveolar macrophages followed infitrasi. Exudative fluid in the alveoli causes lobaris typical consolidation on chest X-ray. Virus, mycoplasma, and chlamydia cause inflammation to the dominance of mononuclear infiltrates in submucosa and interstitial structures. This causes the release of epithelial cells into the airways, as occurs in bronchiolitis.