In Brazil, pneumonia is managed by pulmonologists. Pneumonia is an infection of the alveolar airspaces of the lung, most often bacterial or viral, that fills those airspaces with inflammatory fluid and pus and impairs oxygen exchange. It causes roughly 1.4 million emergency-department visits and 41,000 deaths each year in the United States, and it remains the single largest infectious killer of children under five worldwide (around 700,000 deaths in 2019, per GBD).

Pneumonia (ICD-10: J18 for unspecified organism, J12-J17 by pathogen, J15 for bacterial pneumonia, J84 for atypical patterns) is an acute inflammation of the lung parenchyma in which alveoli — the gas-exchange sacs at the end of the airways — fill with neutrophils, edema fluid, fibrin, and microbial debris. The consolidation that results blocks oxygen from crossing into pulmonary capillaries, which is why hypoxia is the cardinal physiologic finding. Pneumonia is classified by where it was acquired (community-acquired, hospital-acquired, ventilator-associated, or healthcare-associated), by the offending organism (typical bacterial such as Streptococcus pneumoniae; atypical bacterial such as Mycoplasma pneumoniae and Legionella; viral such as influenza, RSV, and SARS-CoV-2; fungal in immunocompromised hosts), and by anatomic pattern on imaging (lobar, bronchopneumonia, interstitial, cavitary). The 2019 ATS/IDSA guideline is the operational reference for community-acquired pneumonia in adults; pediatric guidelines come from the IDSA/PIDS.

The key symptoms of Pneumonia are: Cough productive of yellow, green, rust-colored, or blood-tinged sputum, persisting for several days and worsening rather than improving., Fever with shaking chills, often spiking to 38.5-40°C and accompanied by drenching sweats; older adults may instead present hypothermic., Pleuritic chest pain — a sharp, localized chest discomfort that worsens with deep breaths or coughing, indicating pleural-surface inflammation., Shortness of breath at rest or with minimal exertion; in severe cases, room-air oxygen saturation falls below 92%., Tachypnea (respiratory rate >24/min) and tachycardia (heart rate >100/min) reflecting the body's compensatory response to hypoxia., Fatigue and malaise that can be profound, with many patients describing the inability to climb a single flight of stairs., Confusion or new-onset disorientation, especially in adults over 65 — sometimes the only obvious symptom in this group..

Pneumonia is a clinical diagnosis confirmed by imaging. The workup begins with a focused history (onset, sputum character, travel, sick contacts, vaccinations, immunosuppression) and a physical exam that may reveal focal crackles, bronchial breathing, dullness to percussion, or increased tactile fremitus over the consolidated lung. Vital signs and pulse oximetry establish severity. The single most important test is a chest radiograph: a new opacity confirms the diagnosis, and the pattern (lobar, multifocal, interstitial, cavitary) narrows the pathogen list. When chest X-ray is equivocal or the patient is severely ill, CT chest is more sensitive and is now the preferred modality in many emergency departments. Bloodwork includes CBC, basic metabolic panel, lactate, and procalcitonin; an elevated procalcitonin supports bacterial etiology and helps with antibiotic stewardship. Severity is scored with CURB-65 or the Pneumonia Severity Index to decide outpatient vs ward vs ICU disposition. Pathogen-specific testing (sputum Gram stain and culture, blood cultures, urinary pneumococcal and Legionella antigens, respiratory viral PCR panel, COVID-19 testing) is reserved for hospitalized or severe cases per the 2019 ATS/IDSA guideline. Empirical antibiotic therapy is started while results are pending.
Refer to a pulmonologist for pneumonia that fails to improve after 72 hours of appropriate antibiotics, for recurrent pneumonia in the same lobe (which may signal an obstructing tumor or bronchiectasis), for cavitary or necrotizing disease, and for any patient with risk factors for tuberculosis. Infectious-disease consultation is appropriate for severe CAP with suspected resistant pathogens, immunocompromised hosts, and patients with unexplained eosinophilic pneumonia or fungal disease.
Find specialists →Most patients with uncomplicated outpatient CAP feel substantially better within 5-7 days and return to baseline activity by 2-3 weeks. Fatigue and reduced exercise tolerance often persist 4-6 weeks. Radiographic abnormalities resolve fully in 6-8 weeks in adults under 50 and may take 12 weeks or longer in older adults or those with comorbidities. Patients hospitalized for severe pneumonia typically require 8-12 weeks for full functional recovery and may benefit from pulmonary rehabilitation.
Most uncomplicated pneumonia is managed by primary care or hospitalists. When choosing a pulmonologist for complex or recurrent pneumonia, look for board certification in pulmonary and critical care medicine, hospital affiliation with bronchoscopy and interventional pulmonology services, and experience with the specific complication you face (post-obstructive pneumonia, immunocompromised host pneumonia, suspected nontuberculous mycobacterial disease).
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Mortality from community-acquired pneumonia ranges from under 1% in healthy outpatients to 25-50% in patients requiring ICU admission and mechanical ventilation. The 2019 ATS/IDSA guideline and CURB-65 stratify risk: CURB-65 of 0-1 carries 30-day mortality below 3%; a score of 4-5 carries mortality of 30% or higher. Clinical stability — defined as resolution of fever, normalization of vital signs, ability to take oral medication, and SpO2 ≥90% on room air — is typically reached by day 3 in responders; failure to stabilize by day 3 should prompt reassessment for resistant organisms, structural disease, parapneumonic effusion, or alternative diagnosis. Radiographic resolution lags clinical recovery by 4-8 weeks. Long-term, severe pneumonia in older adults is independently associated with a 30-50% increased risk of cardiovascular events in the year after recovery and accelerated functional decline; pulmonary rehabilitation and post-discharge follow-up at 4-6 weeks improve outcomes.
During acute pneumonia, rest is appropriate until fever resolves and oxygen saturation is stable. Begin low-intensity walking by week 2 in mild cases. Pulmonary rehabilitation — 6-8 weeks of supervised exercise plus education — measurably accelerates functional recovery after severe pneumonia, especially in older adults and those with underlying COPD.
Medically reviewed by AIHealz Medical Editorial Board · May 12, 2026