From the Guidelines
Pneumonia is primarily caused by bacteria, viruses, and fungi that invade the lungs, with Streptococcus pneumoniae being the most common bacterial cause and influenza viruses being frequent viral culprits, as reported in the most recent study 1. The causes of pneumonia can be categorized into several groups, including:
- Bacterial pneumonia, which is often caused by Streptococcus pneumoniae, Haemophilus influenzae, and Chlamydophila pneumoniae
- Viral pneumonia, which is often caused by influenza viruses, respiratory syncytial virus, and adenovirus
- Fungal pneumonia, which is often caused by fungi such as Aspergillus fumigatus and Pneumocystis jirovecii
- Aspiration pneumonia, which occurs when food, liquid, or vomit is inhaled into the lungs
According to the study 1, the most common pathogens responsible for community-acquired pneumonia (CAP) include:
- Streptococcus pneumoniae
- Influenza viruses
- Haemophilus influenzae
- Chlamydophila pneumoniae
- Respiratory syncytial virus
- Adenovirus
The study also notes that the incidence of viral etiology in ICU patients with CAP is increasing, with a high incidence of post-influenza bacterial pneumonia and significant mortality up to 10% with both seasonal and pandemic influenza 1.
Risk factors that increase susceptibility to pneumonia include:
- Weakened immune systems
- Smoking
- Chronic diseases
- Advanced age
- Hospitalization
Symptoms of pneumonia typically include:
- Cough with phlegm
- Fever
- Chills
- Difficulty breathing
- Chest pain
Treatment of pneumonia depends on the cause, with bacterial pneumonia requiring antibiotics like amoxicillin or azithromycin, while viral pneumonia often resolves with supportive care 1. Prevention includes vaccination against pneumococcal bacteria and influenza, good hand hygiene, and avoiding smoking.
From the Research
Causes of Pneumonia
- Pneumonia can be caused by various microorganisms, including bacteria, viruses, and fungi 2, 3, 4, 5, 6
- The most common cause of bacterial pneumonia is Streptococcus pneumoniae, a gram-positive diplococcus 2, 3, 4, 5, 6
- Other common bacterial causes of pneumonia include Haemophilus influenzae, Klebsiella organisms, and Staphylococcus aureus 3, 6
- Viral pneumonia can be caused by influenza, adenoviruses, and other viruses 3
- Fungal pneumonia can be caused by opportunistic fungi, such as Candida, Aspergillus, and Phycomycetes, as well as fungi like Histoplasma capsulatrum, Blastomyces dermatitides, and Coccidioides immitis 3
Risk Factors for Pneumonia
- Comorbidities, such as previous antibiotic therapy, can increase the risk of developing pneumonia 2
- Nursing home patients and hospitalized patients with severe pneumonia are at higher risk of developing pneumonia 2
- Patients with compromised immune systems, such as those with HIV/AIDS or undergoing chemotherapy, are at higher risk of developing opportunistic fungal pneumonia 3
Diagnosis and Treatment of Pneumonia
- Diagnosis of pneumonia is usually confirmed by chest x-ray and gram stain 4
- Treatment of pneumonia typically involves antibiotic therapy, with the choice of antibiotic depending on the causative microorganism and local resistance patterns 2, 3, 5, 6
- Vaccination, such as with PPSV23 and PCV13, can be effective in preventing pneumococcal infection 4