Community-acquired pneumonia

Editor-In-Chief: Prab R Tumpati, MD
Obesity, Sleep & Internal medicine
Founder, WikiMD Wellnesspedia &
W8MD medical weight loss NYC and sleep center NYC

Community-acquired pneumonia
Synonyms	N/A
Pronounce	N/A
Specialty	N/A
Symptoms	Cough, fever, chest pain, difficulty breathing
Complications	Pleural effusion, lung abscess, sepsis
Onset	Rapid
Duration	Varies
Types	N/A
Causes	Bacterial infection, viral infection, fungal infection
Risks	Smoking, chronic lung disease, immunosuppression
Diagnosis	Chest X-ray, sputum culture, blood tests
Differential diagnosis	Pulmonary embolism, chronic obstructive pulmonary disease, asthma
Prevention	Vaccination, hand hygiene, smoking cessation
Treatment	Antibiotics, antiviral drugs, supportive care
Medication	Amoxicillin, azithromycin, oseltamivir
Prognosis	Generally good with treatment
Frequency	Common
Deaths	Significant, especially in the elderly and those with comorbidities

Community-acquired pneumonia (CAP) is a type of pneumonia that is acquired outside of a hospital or healthcare setting. It is a common illness that affects the lungs and can be caused by a variety of pathogens, including bacteria, viruses, and fungi.

Etiology

The most common cause of community-acquired pneumonia is the bacterium Streptococcus pneumoniae. Other bacterial causes include Haemophilus influenzae, Mycoplasma pneumoniae, and Chlamydophila pneumoniae. Viral causes include influenza virus, respiratory syncytial virus (RSV), and coronavirus. Fungal causes are less common but can include Histoplasma capsulatum and Coccidioides immitis.

Pathophysiology

Community-acquired pneumonia occurs when pathogens enter the lower respiratory tract and overcome the host's immune defenses. This can lead to inflammation and consolidation of the lung tissue, resulting in impaired gas exchange and respiratory symptoms.

Clinical Presentation

Patients with community-acquired pneumonia typically present with symptoms such as cough, fever, chills, dyspnea (shortness of breath), and pleuritic chest pain. Physical examination may reveal signs such as crackles or decreased breath sounds over the affected lung area.

Diagnosis

Diagnosis of community-acquired pneumonia is based on clinical presentation, physical examination, and imaging studies such as a chest X-ray. Laboratory tests, including sputum culture and blood tests, may be used to identify the causative organism.

Treatment

The treatment of community-acquired pneumonia depends on the severity of the illness and the suspected or confirmed pathogen. Antibiotics are the mainstay of treatment for bacterial pneumonia, with common choices including amoxicillin, azithromycin, and doxycycline. Antiviral medications may be used for viral pneumonia, and supportive care is important for all patients.

Prognosis

The prognosis for community-acquired pneumonia varies depending on the patient's age, comorbidities, and the severity of the illness. Most patients recover with appropriate treatment, but complications such as pleural effusion, lung abscess, and sepsis can occur.

Prevention

Preventive measures for community-acquired pneumonia include vaccination against Streptococcus pneumoniae and influenza, smoking cessation, and good hand hygiene.

Also see

• Hospital-acquired pneumonia
• Aspiration pneumonia
• Pneumonia
• Respiratory tract infection