Pneumonia is an acute respiratory condition characterized by inflammation of the lung tissue, primarily due to infection from bacteria, viruses, or fungi, excluding tuberculosis. It can affect one or both lungs and leads to the accumulation of fluid or pus in the alveoli, impairing oxygen exchange. Pneumonia can vary in severity, ranging from mild to life-threatening, particularly in vulnerable populations such as the elderly, infants, and individuals with compromised immune systems.

Several factors increase the risk of developing pneumonia, including age, chronic health conditions like asthma or COPD, and weakened immune function due to diseases like HIV/AIDS or cancer. Additionally, smoking and exposure to secondhand smoke significantly elevate the risk. Environmental factors, such as living in close quarters or crowded conditions, and recent respiratory infections can also predispose individuals to pneumonia.

Common symptoms of pneumonia include cough (which may produce phlegm), fever, chills, shortness of breath, and chest pain that worsens with coughing or deep breaths. Some individuals may experience fatigue, nausea, and confusion, particularly older adults. Symptoms can develop gradually or suddenly, often mimicking those of a cold or flu initially.

Pneumonia, excluding tuberculosis, is primarily caused by a variety of pathogens including bacteria, viruses, and fungi. Common bacterial agents include Streptococcus pneumoniae and Haemophilus influenzae, while viral pneumonia may be triggered by influenza or respiratory syncytial virus (RSV). Aspiration pneumonia can occur when food, liquid, or vomit is inhaled into the lungs, creating an environment for infection. Additional risk factors include smoking, chronic lung diseases, weakened immune systems, and age, especially in very young or elderly individuals.

Diagnosis of pneumonia typically involves a thorough medical history and physical examination, followed by imaging tests such as a chest X-ray to identify areas of opacity in the lungs. Laboratory tests, including blood tests and sputum cultures, may be conducted to determine the causative organism and guide appropriate treatment. In some cases, pulse oximetry may be used to assess the level of oxygen in the blood.

The treatment of pneumonia typically depends on its cause and severity. Bacterial pneumonia is often treated with antibiotics, guided by the specific organism responsible for the infection, while antiviral medications may be used for viral pneumonia in some cases. Supportive care, including supplemental oxygen, fluids, and rest, is also essential for recovery. In severe cases or those requiring hospitalization, additional interventions such as intravenous antibiotics or respiratory support may be necessary.

Preventive measures for pneumonia include vaccination against common pathogens such as Streptococcus pneumoniae and influenza viruses, which can significantly reduce incidence rates. Good hygiene practices, such as regular handwashing and avoiding close contact with sick individuals, are also vital. Maintaining a healthy lifestyle through a balanced diet, regular exercise, and smoking cessation can bolster the immune system and decrease susceptibility to infections.