Lung Abscess - Necrosis of Lung Tissue

Introduction

A lung abscess is also called a pus cavity in the lung due to the accumulation of microorganisms. It occurs when the lung tissues die (within a necrotic region) due to bacterial inhabitants, usually after serious pneumonia. The body attempts to fight the infection, but it leads to the degeneration of the lung tissue, forming a cavity filled with pus instead of air. Their symptoms include chest pain and cough with purulent or blood-stained sputum. The condition is mostly in most patients; however, an abscess may require surgical drainage in a few others.

What Are the Causes of Lung Abscesses?

Lung abscesses may arise due to several etiological factors, the most important being bacterial infection. If appropriate treatment is not provided, pyogenic pneumonia caused by foreskin bacteria such as Staphylococcus aureus, Klebsiella pneumoniae, and Streptococcus might develop an abscess. These are termed ‘necrotizing pneumonia’ as these bacteria produce severe inflammation in the lung, leading to necrosis and edema and, eventually, pus cavity formation.

In other instances, tuberculosis and fungal infection-related factors can also lead to a lung abscess, especially when there is no chance of recovery from the disease or it reaches an advanced stage and can destroy lung tissue.

This lung abscess rarely occurs, but when it does, the underlying cause is primarily respiratory stenosis. Respiratory stenosis is when air passages are narrowed or obstructed due to mucus, a tumor, or even a foreign entity. Because of this obstruction, lung secretions are inadequately drained, allowing bacterial infection and further possible abscess formation.

Another cause of abscess formation is septicemia, which is defined as blood poisoning. In such situations, any bacteria growing in an infected section of the body can break into the blood vessels. When this occurs, a metastatic lung abscess develops. Such conditions are common in patients susceptible to infections or high-grade infections.

Apart from that, bronchiectasis, which occurs when bronchial tubes are widened and damaged by infections, may lead to the formation of lung abscesses. This situation is unpleasant as the lungs can house such infected materials, which increases the formation of abscesses.

Also, endotracheal suction of biological fluids, be it food, infusion liquids, or gastric content, into the lungs can cause infection and oozing, especially in those with swallowing difficulties or impaired consciousness.

What Are the Clinical Symptoms and Signs of Lung Abscess?

The lungs are inflamed in almost all cases, and high-grade fever is the most common abnormal finding. Most patients experience high-grade fever frequently associated with chills and night sweats, an indication of infection in the body. There is weakness and tiredness due to lack of energy. In most cases, getting rid of the infection is troublesome, with the patient suffering from a productive cough most of the time. Often, the patient coughs up phlegm containing pus from the abscess cavity, which has a foul smell and a thick consistency. In more extreme cases, the sputum may be minimal in clearing off the blood or associated with hemoptysis (coughing blood).

On physical examination, signs may include decreased breath sounds over the lung area where the abscess has formed due to tissue destruction. Crackles may also be heard through a stethoscope, indicating abnormal lung sounds. In chronic or severe cases, clubbing of the fingers and a rounded, swollen appearance of the fingertips may develop signs of prolonged low oxygen levels in the blood. Cyanosis (a bluish tint to the skin and lips) may also occur in patients with severe lung abscesses, indicating poor oxygenation. Lastly, systemic symptoms such as weight loss and loss of appetite are common in individuals with a long-standing or severe infection, contributing to a general decline in health.

How Is Lung Abscess Diagnosed?

• Chest X-ray.
• ESR (erythrocyte sedimentation rate) is high.
• CRP (C-reactive protein) is high.
• CBC (complete blood count).
• Bronchoscopy.
• CT (computerized tomography) scan if needed.

What Are the Effects of Lung Abscess?

• Hemoptysis (Coughing up Blood): Coughing up blood as a symptom of coughing is called hemoptysis and is the most frequent sequelae of lung abscess. As the cavity gets more infected, the possibility goes that it starts to melt the adjacent blood vessels and, therefore, there is the prospect of blood flowing through in and, hence, there may be blood or blood-tinged sputum. In extreme circumstances bleeding may be extensive and even fatal necessitating immediate surgical procedures.
• Spread of Infection to Other Organs: Infection from the lung abscess in spite of containing the abscess may enter the bloodstream, abscess will develop in different places in the body, which are termed secondary infections, such as abscess of the brain, which is referred as cerebral abscess. This happens, when bacteria seep from the lungs into blood and then into the brain, which is quite severe and increases the risk of various neurological symptoms such as, epileptic attacks, altered mental state and headache.
• Pleural Cavity Rupture (Empyema): In some cases, the lung abscess can rupture into the pleural cavity, the space between the lungs and the chest wall. This leads to the accumulation of pus in the pleural space, a condition known as empyema. Empyema causes severe chest pain and difficulty breathing and can lead to further infection and respiratory failure if not treated. The rupture may also cause a pneumothorax (collapsed lung), adding to the severity of the condition.

How Is Lung Abscess Treated?

• Antibiotic Therapy: Unlike drainage, the initial line of treatment for lung abscess is the administration of global antibiotics to eradicate the underlying infective process. The choice of antibiotics is relative to the bacteria suspected or confirmed responsible for the abscess and covers several anaerobic bacteria to start with. Recommended medications include Benzylpenicillin and Metronidazole or similar antibiotics. Treatment may be switched to more specific antibiotics once bacterial pathogens are detected and identified from sputum or cultures of abscess fluid. In principle, the treatment course lasts for several weeks, or longer if necessary, to prevent the recurrence of the abscess.
• Drainage of the Abscess: Drainage of the abscess is indicated in patients with a rapidly enlarging abscess or those who fail to respond adequately to antibiotics.
• Supportive Care: In addition to the specific therapies, the patients may require supportive measures to provide symptomatic relief and foster recovery. This comprises oxygen when breathing problems are noted, fluids for hydration, and medications to relieve cleavage of pain in the chest.

Conclusion

A lung abscess is a grave condition involving the infectious destruction of the lung parenchyma, which results in a pus-filled cavity. Timely antibiotic treatment and, in some cases, drainage or surgery is necessary to avoid complications like hemoptysis or the advancement of the infection. Early diagnosis and proper treatment make a notable difference for patients with lung abscesses.