Pneumonia

Pneumonia
Name	Pneumonia
Synonyms	Pneumonitis
Caption	A chest radiograph showing a classic lobar pneumonia caused by Streptococcus pneumoniae.
Field	Pulmonology, Infectious disease
Symptoms	Cough, fever, shortness of breath, sputum production
Complications	Sepsis, pleural effusion, empyema, acute respiratory distress syndrome
Onset	Rapid or gradual
Duration	Weeks
Causes	Bacteria, viruses, fungi, parasites
Risks	Chronic obstructive pulmonary disease, asthma, diabetes, heart failure, smoking, immunodeficiency
Diagnosis	Based on symptoms, chest X-ray, blood tests, sputum culture
Prevention	Vaccinations, handwashing, smoking cessation
Treatment	Antibiotics, antiviral drugs, oxygen therapy
Medication	Amoxicillin, doxycycline, azithromycin
Prognosis	Generally good with treatment
Frequency	~450 million per year (global)
Deaths	~4 million per year (global)

Pneumonia. It is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include a combination of productive or dry cough, chest pain, fever, and difficulty breathing. The condition can range in severity from mild to life-threatening and is a significant cause of morbidity and mortality worldwide, particularly among the very young, the elderly, and those with underlying health problems.

Signs and symptoms

Common symptoms include fever, often accompanied by chills and rigor, a cough that may produce greenish or yellow sputum, and pleuritic chest pain. Patients frequently experience shortness of breath and tachypnea. In severe cases, cyanosis, confusion, and sepsis may develop. Elderly individuals may present with delirium or a general decline in function rather than classic respiratory symptoms. Physical examination findings can include crackles or bronchial breath sounds heard on auscultation with a stethoscope.

Causes

The infection can be caused by a wide array of pathogens, including bacteria, viruses, fungi, and parasites. The most common bacterial cause worldwide is Streptococcus pneumoniae. Other significant bacterial agents include Haemophilus influenzae, Staphylococcus aureus, and Klebsiella pneumoniae. Common viral causes include influenza virus, respiratory syncytial virus (RSV), and SARS-CoV-2. Mycoplasma pneumoniae is a notable cause of atypical pneumonia. Risk is increased by conditions such as chronic obstructive pulmonary disease (COPD), HIV/AIDS, and use of immunosuppressive drugs.

Diagnosis

Diagnosis is often suspected based on symptoms and physical exam, and confirmed by imaging. A chest radiograph is the most common imaging study, typically showing areas of consolidation. Further tests may include blood tests such as a complete blood count to check for leukocytosis and inflammatory markers like C-reactive protein. Sputum culture and blood culture can identify the causative organism. In severe or complicated cases, a computed tomography (CT) scan of the chest or bronchoscopy may be performed.

Prevention

Prevention strategies include vaccination, which is effective against common bacterial and viral causes. Key vaccines include the pneumococcal conjugate vaccine (PCV13), the pneumococcal polysaccharide vaccine (PPSV23), and the annual influenza vaccine. Other measures encompass smoking cessation, reducing exposure to air pollution, hand hygiene with soap and water or alcohol-based hand sanitizer, and appropriate infection control practices in healthcare settings like hospitals.

Management

Treatment depends on the cause and severity. Bacterial pneumonia is treated with antibiotics, with choices guided by local resistance patterns and patient factors; common first-line agents include amoxicillin, doxycycline, or macrolides like azithromycin. For viral causes, antiviral drugs such as oseltamivir may be used. Supportive care is critical and includes oxygen therapy for hypoxemia, intravenous fluids, and fever management with medications like acetaminophen. Severe cases requiring hospital admission may need mechanical ventilation in an intensive care unit.

Prognosis

With appropriate treatment, most otherwise healthy individuals recover fully. However, pneumonia remains a leading cause of death globally. Prognosis is worse in individuals with comorbidities such as congestive heart failure, chronic kidney disease, or liver cirrhosis. Complications like pleural effusion, empyema, lung abscess, or acute respiratory distress syndrome (ARDS) can significantly worsen outcomes. Scoring systems like the CURB-65 criteria are used to assess severity and predict mortality.

Category:Respiratory diseases Category:Infectious diseases