From the Guidelines
Pneumonia is primarily caused by the invasion of pathogens, such as bacteria, viruses, or fungi, into the lungs, where they multiply and trigger an inflammatory response. The mechanism behind pneumonia involves these pathogens entering the lungs through various routes, including inhalation of airborne particles, aspiration of oral or gastric contents, or through the bloodstream from another infection site 1.
Key Mechanisms:
- Aspiration of oropharyngeal organisms is believed to be the most important route for both nosocomial and community-acquired pneumonia 1.
- Inhalation of aerosols containing bacteria and hematogenous spread from a distant body site are other possible mechanisms 1.
- Bacterial translocation from the gastrointestinal tract has also been hypothesized as a mechanism for infection 1. Once in the lungs, the pathogens cause inflammation in the air sacs (alveoli), which can fill with fluid or pus, making gas exchange difficult and leading to symptoms like cough, fever, difficulty breathing, and chest pain.
Pathogen-Specific Mechanisms:
- Bacterial pneumonia often causes more rapid onset and lobar consolidation, while viral pneumonia may cause more diffuse inflammation.
- Risk factors for pneumonia include weakened immune systems, chronic diseases, smoking, and advanced age. Treatment depends on the causative pathogen but typically includes antibiotics for bacterial pneumonia, supportive care for viral pneumonia, and in severe cases, oxygen therapy or mechanical ventilation to support breathing while the infection resolves 1.
From the Research
Mechanism of Pneumonia
The mechanism behind pneumonia is complex and involves various factors, including:
- The host immune response, which plays a crucial role in the development of the disease 2
- The type of microorganism causing the infection, such as bacteria, respiratory viruses, or fungi 2, 3
- The presence of underlying chronic conditions, which can increase susceptibility to pneumonia 2, 3
- The geographical location, which can affect the prevalence of certain microorganisms 2
Inflammation and Pneumonia
Inflammation is a key component of the immune response to respiratory infections, and variations in inflammation can influence pneumonia susceptibility and severity 4
- Inflammation can be affected by various factors, including the type of microorganism and the host's immune response
- Understanding the role of inflammation in pneumonia can help in the development of new treatments and therapies
Pathophysiology of Pneumonia
The pathophysiology of pneumonia involves the infection of the alveoli and distal airways, leading to inflammation and damage to the lung tissue 2, 5
- The type of microorganism causing the infection can affect the pathophysiology of the disease, with atypical pathogens such as Mycoplasma pneumoniae and Legionella species requiring different therapeutic approaches 5
- The host's immune response plays a crucial role in determining the severity and outcome of the disease
Diagnosis and Treatment
Diagnosis of pneumonia is based on clinical presentation and radiological findings, and it is crucial to identify the causative pathogens to guide treatment 2, 3
- Treatment of pneumonia depends on the type of microorganism causing the infection and the severity of the disease, with antibiotics and antimicrobial therapy being commonly used 3, 5
- New therapies and diagnostic tests are being developed to improve the management of pneumonia, including the use of azithromycin in viral infections 6