Lung abscess: what is it, symptoms, treatment, prognosis

What is a lung abscess?

Lung abscess is a necrotic focus in the lung tissue with purulent contents, delimited from the healthy part of the organ by a pyogenic membrane. Currently, in developed countries, this pathology is quite rare. In most cases, it occurs in immunocompromised individuals, alcoholics or heavy smokers.

Causes and risk factors

Usually, a lung abscess is caused by bacteria that normally live in the mouth or throat and are inhaled (aspirated) into the lungs, resulting in an infection. Gum disease (periodontal disease) is often the source of bacteria that cause lung abscess.

The human body has many ways to protect itself (such as coughing) from bacteria entering the lungs. Infection mainly occurs when a person is unconscious or very drowsy. due to the use of sedatives, anesthesia, alcohol or drug abuse, nervous systems.

In people with a weakened immune system, a lung abscess can be caused by organisms that are not usually found in the mouth or throat, such as fungi or Mycobacterium tuberculosis 

Mycobacterium tuberculosis (a microorganism that causes tuberculosis). Other bacteria that can cause lung abscesses are streptococci and staphylococci, including methicillin-resistant Staphylococcus aureus (MRSA), which causes a serious infection.

Blockage (obstruction) of the airways can also lead to abscess formation. If the branches of the windpipe (bronchi) are blocked by a tumor or foreign body, secretions (mucus) may accumulate behind the obstruction, causing abscess. Sometimes bacteria get into such secretions. The obstruction prevents secretions and bacteria from being cleared through the airways.

Less commonly, abscesses occur when bacteria or infected blood clots are carried through the bloodstream into the lungs from another infected area of ​​the body (septic pulmonary emboli).

Typically, a person develops only one lung abscess as a result of aspiration or airway obstruction. If there are several abscesses, then they, most often, affect the same lung. If the infection enters the lung through the bloodstream, many scattered abscesses can develop in both lungs. This problem is most common among people who use dirty needles or non-sterile methods to inject drugs.

Ultimately, in most cases, abscesses break into the airways, which contributes to the formation of phlegm, which is excreted from the body with a cough. A ruptured abscess leaves a cavity in the lung that is filled with fluid and air. Sometimes an abscess bursts into the space between the lungs and the chest wall (pleural cavity), filling it with pus. The accumulation of pus in the pleural space is called empyema. In rare cases, an abscess can destroy the blood vessel wall, which can lead to severe bleeding.

Symptoms and Signs

Symptoms tend to develop slowly. However, depending on the cause of the occurrence abscess, symptoms may appear unexpectedly. Early symptoms include:

• fatigue;

• loss of appetite;
• sweating at night;
• fever;
• cough with sputum.

The phlegm may have an unpleasant odor (common with bacteria from the mouth and throat) and may contain streaks of blood. In addition, when breathing, the patient may feel chest pain, especially if the outer lining of the lungs and the inner lining of the chest wall (pleura) are inflamed. Many patients seek medical attention only a few weeks or even months after the first onset of such symptoms. Such people develop chronic abscesses and, in addition to other symptoms, have significant weight loss, daytime fever, and night sweats. Lung abscesses due to Staphylococcus aureus Staphylococcus aureus or MRSA, on the other hand, can be fatal within days, sometimes even hours.

Complications

If a lung abscess breaks into the pleural cavity, a pyopneumothorax is formed.

The unfavorable course of pulmonary suppuration contributes to the development of complications, often requiring surgical intervention. These include:

1. Pyopneumothorax.
2. Empyema of the pleura.
3. Subcutaneous emphysema.
4. Pulmonary bleeding.
5. Sepsis.
6. Metastatic brain abscesses.
7. Acute Respiratory Distress Syndrome.

Diagnostics

The doctor may suspect the diagnosis of "lung abscess" by a combination of clinical signs, taking into account the patient's complaints, the history of his disease and an objective examination. Additional laboratory and instrumental studies help him to confirm the diagnosis.

1. A clinical blood test (confirms the presence of bacterial inflammation by the presence of leukocytosis, a shift in the white blood formula to the left, an increase ESR).
2. Sputum analysis (when settling, the sputum is divided into three layers: the upper one is foamy, consists of mucus mixed with pus, the middle one is is a mixture of saliva with a serous component and the lower one has a heterogeneous structure, it contains pus, scraps of pulmonary fabrics, etc.; microscopic examination reveals a variety of microorganisms and a large number of neutrophils).
3. X-ray of the chest organs (at the beginning of the disease, it reveals a darkening area with fuzzy contours, after opening the abscess - a cavity with thick walls and a horizontal fluid level).
4. Computed tomography (it is a more accurate method and is used in the case when the data of conventional radiography for making a diagnosis is not enough).
5. Bronchoscopy (prescribed in doubtful cases in order to clarify the localization of the abscess and the patency of the draining bronchus).

The key to success in making an accurate diagnosis is differential diagnosis with:

• pulmonary tuberculosis;
• lung cancer;
• festering cyst;
• bronchiectasis.

Standard treatments

Due to the severity of the course and the high risk of complications, the treatment of infectious lung destruction is carried out in a hospital setting.

Conservative treatment is aimed at suppressing the infectious process, adequate drainage of purulent cavities and their sanitation.

1. All patients with lung abscess are prescribed antibiotic therapy. At the first stage, drugs from the group of aminoglycosides, cephalosporins, macrolides, carbapenems are used in high doses. After bacteriological examination of sputum and determination of the sensitivity of pathogenic microorganisms to antibiotics, correction of therapy can be performed. In this case, the course of treatment is on average 6 weeks.
2. In order to improve bronchial patency and drainage, bronchodilators, expectorant and mucolytic drugs are prescribed. If these measures are not effective, such patients are shown repeated endoscopic sanitation with intrabronchial administration of antiseptics, antibiotics and proteolytic enzymes.
3. In parallel with this, detoxification therapy is carried out with intravenous infusion of plasma-substituting solutions, hemosorption. If indicated, oxygen therapy is used.
4. To improve the impaired immunological reactivity, various immunocorrectors are used (thymus preparations, etc.).

With the ineffectiveness of conservative therapy or the development of complications, surgical treatment is indicated for such patients.

Forecast

The prognosis for a lung abscess is determined by the severity of its course, the presence of complications, the general reactivity of the body and the adequacy of the therapeutic tactics of managing the patient. Mortality among patients with suppuration of the lungs reaches 10-15 percent.

It should be noted that in most cases, with timely and correct treatment, patients with an acute destructive process in the lung tissue experience clinical recovery. In some of them with complete obliteration of the pathological focus, and in some - with the preservation of the cavity and pneumofibrosis around it. At the same time, good drainage and epithelialization of the inner surface of the abscess cavity contribute to the cessation of the purulent process. This condition can last for many years, but under adverse conditions that weaken the immune system, a repeated outbreak of infection with the development of the disease is possible. In 15-20 percent of such patients, a chronic lung abscess is formed.