What are the causes of lung abscess?

There are many causes of lung abscess, mainly due to purulent lesions caused by the tissues around the lungs. Early lung abscess is caused by inflammation, which then slowly leads to abscess. The main population suffering from lung abscess is young men. The main symptoms of the disease include high fever, chest pain, coughing up large amounts of thick sputum, and in severe cases, coughing up blood. It is recommended to undergo relevant examinations to find out whether you have lung abscess.

Lung abscess is a purulent inflammation of lung tissue caused by infection with various pathogens, leading to tissue necrosis, destruction, and liquefaction to form an abscess. The main clinical features are high fever, cough, and coughing up large amounts of foul-smelling sputum. Common pathogens include Staphylococcus aureus, Streptococcus pyogenes, Klebsiella pneumoniae and Pseudomonas aeruginosa.

Causes

Pathogens are often colonizers of the upper respiratory tract and oral cavity, including aerobic, anaerobic and facultative anaerobic bacteria. 90% of patients with lung abscess have concurrent anaerobic infection, and highly virulent anaerobic bacteria can cause disease alone in some patients. Common other pathogens include Staphylococcus aureus, Streptococcus pyogenes, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Escherichia coli and Haemophilus influenzae can also cause necrotizing pneumonia. Lung abscesses are classified into the following types based on the route of infection:

Aspiration lung abscess

Pathogens are inhaled into the body through the mouth, nose, and pharynx and cause illness. Under normal circumstances, inhaled substances can be quickly cleared by the airway mucociliary transport system, cough reflex and lung macrophages. However, when there is a disorder of consciousness, such as under anesthesia, drunkenness, drug overdose, epilepsy, cerebrovascular accident, or due to factors such as cold and extreme fatigue, the systemic immunity and airway defense and clearance functions are reduced, and inhaled pathogens can cause disease. In addition, the disease may also be caused by inhalation of purulent secretions from sinusitis, alveolar abscess, etc. Abscesses are often solitary, and their location is related to bronchial anatomy and body position. Because the right main bronchus is steeper and straighter and has a larger diameter, inhaled blood can easily enter the right lung. When lying on the back, it is more likely to occur in the posterior segment of the upper lobe or the dorsal segment of the lower lobe; when sitting, it is more likely to occur in the posterior basal segment of the lower lobe; when lying on the right side, it is more likely to occur in the anterior or posterior segment of the right upper lobe. Pathogens are mostly anaerobic bacteria.

Secondary lung abscess

Certain bacterial pneumonia, such as Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumonia, as well as secondary infections such as bronchiectasis, bronchial cysts, bronchial lung cancer, and tuberculosis cavities can lead to secondary lung abscesses. Bronchial foreign body obstruction is also an important factor leading to lung abscess, especially in children. Purulent lesions of organs adjacent to the lungs, such as subphrenic abscess, perirenal abscess, spinal abscess or esophageal perforation, which spread to the lungs may also cause lung abscess. Amoebic liver abscess often occurs at the top of the right liver and can easily penetrate the diaphragm to the right lower lobe of the lung, forming an amoebic lung abscess.

Hematogenous lung abscess

Due to bacteremia caused by skin trauma infection, furuncle, carbuncle, otitis media or osteomyelitis, bacterial thrombi spread to the lungs through the bloodstream, causing small blood vessel embolism, inflammation and necrosis to form lung abscess. Intravenous drug users who have right-sided bacterial endocarditis may have tricuspid valve vegetation that detaches and blocks the small blood vessels in the lungs, forming lung abscesses, which are often multiple abscesses in the outer fields of both lungs. The most common pathogens are Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus.