From the Guidelines
Lobar pneumonia is primarily caused by bacterial infections, most commonly Streptococcus pneumoniae (pneumococcus). This type of pneumonia affects one or more lobes of the lungs completely. Other bacteria that can cause lobar pneumonia include Klebsiella pneumoniae, Haemophilus influenzae, and Staphylococcus aureus, as noted in the guidelines for the management of community-acquired pneumonia in adults 1, 2. The infection typically begins when these bacteria are inhaled into the lungs or spread from the bloodstream. Risk factors include advanced age, smoking, alcohol abuse, chronic diseases, and weakened immune systems. The bacteria multiply in the lung tissue, causing inflammation and fluid accumulation in the affected lobe. This leads to the characteristic symptoms of fever, cough with sputum, chest pain, and difficulty breathing.
Causes and Risk Factors
- Bacterial infections, most commonly Streptococcus pneumoniae (pneumococcus) 1
- Other bacteria such as Klebsiella pneumoniae, Haemophilus influenzae, and Staphylococcus aureus 2
- Risk factors: advanced age, smoking, alcohol abuse, chronic diseases, and weakened immune systems
- Infection can begin through inhalation of bacteria into the lungs or spread from the bloodstream
Diagnosis and Treatment
Treatment usually involves antibiotics such as amoxicillin (500-875 mg three times daily for 5-7 days), azithromycin (500 mg on day 1, then 250 mg daily for 4 days), or levofloxacin (750 mg daily for 5 days) depending on the suspected pathogen and local resistance patterns, as recommended by the Infectious Diseases Society of America/American Thoracic Society consensus guidelines 3. Supportive care with rest, hydration, and sometimes oxygen therapy is also important for recovery. It's essential to consider the need for specific anaerobic coverage, which is generally overestimated, and is clearly indicated only in the classic aspiration pleuropulmonary syndrome 3.
Management Considerations
- Antibiotic selection should consider local resistance patterns and the severity of illness
- Supportive care, including rest, hydration, and oxygen therapy, is crucial for recovery
- Specific anaerobic coverage is only necessary in certain cases, such as the classic aspiration pleuropulmonary syndrome 3
From the Research
Causes of Lobar Pneumonia
- Bacteria are the primary cause of lobar pneumonia, with Streptococcus pneumoniae and Staphylococcus aureus being the most common pathogens 4
- Haemophilus influenzae type b is also a common cause of lobar pneumonia 4
- Viruses, such as bocavirus and influenza, can also cause lobar pneumonia, although they are less common than bacterial causes 4
- Coinfections with multiple pathogens are frequent, with Moraxella catarrhalis often coinfected with S. pneumoniae 4
Pathogens and Their Susceptibility to Antibiotics
- S. pneumoniae, H. influenzae, and M. catarrhalis have varying levels of susceptibility to different antibiotics 5, 6, 7, 8
- S. pneumoniae is susceptible to respiratory fluoroquinolones, amoxicillin, and amoxicillin/clavulanic acid, but has increasing resistance to penicillins, cephalosporins, macrolides, and trimethoprim-sulfamethoxazole 5, 6, 7
- H. influenzae is susceptible to amoxicillin/clavulanic acid, ceftriaxone, and fluoroquinolones, but has significant beta-lactamase production and resistance to trimethoprim/sulfamethoxazole 5, 7, 8
- M. catarrhalis is resistant to amoxicillin, cefaclor, cefprozil, and trimethoprim/sulfamethoxazole, but is susceptible to amoxicillin/clavulanic acid, ceftriaxone, and fluoroquinolones 5, 7, 8