What is a lung abscess?
A lung abscess is a cavity in the lung that is filled with pus. Due to an inflammatory reaction, lung tissue dies (necrosis) and a pus-filled cavity, the lung abscess, develops. The cause is usually bacteria that colonize the mouth and throat. On the one hand, the germs can enter the lungs through the air we breathe, and on the other through the bloodstream. These are usually bacteria that multiply without oxygen – so-called anaerobes. Some parasites can also cause a lung abscess. It is less common in cases of pneumonia, pulmonary infarction or lung cancer.
The lung abscess triggers general symptoms such as coughing, fever, tiredness and fatigue. Such symptoms are not typical of a lung abscess, but can occur in the context of many diseases. A more specific symptom is coughing up purulent secretions, sometimes with blood. An X-ray examination of the lungs shows with a high degree of certainty whether an abscess has formed in the lungs.
This localized lung infection can be treated well with antibiotics and usually heals completely without leaving a defect. Antibiotics slow down the multiplication of pathogens and kill them. However, you usually have to take this medication for a long time to eliminate all bacteria. Complications are rare, such as further spread of the inflammation in the lungs or spread of the pathogens via the bloodstream.
Lung abscess – frequency and age
Lung abscesses have become rather rare today – thanks to the early use of antibiotic therapy. There are no exact figures on the frequency and age of those affected. Elderly people who can no longer swallow properly, for example because they suffer from neurological diseases such as stroke, Alzheimer’s or Parkinson’s, are often at risk. As a result, liquid or even parts of the food go directly into the windpipe instead of the esophagus. These bacterial secretions from the mouth and throat then enter the lungs with the air we breathe. Lung abscesses are also more common in people with an immunodeficiency (due to medication or illness, such as alcoholics or people with diabetes).
Lung abscess: causes and risk factors
Lung abscesses are usually caused by bacteria found in the mouth and throat. They are located, for example, in the grooves of the tonsils or in the folds of the gums. People with poor oral hygiene and diseases of the gums and periodontium are particularly prone to “pathogens”. These bacteria can then enter the deeper airways – the lungs and bronchi – with the air we breathe.
Germs can also be washed into the lungs directly via the bloodstream. These pathogens originate from other sources of infection in the body and are secondarily distributed with the blood to other organs (commonly known as “blood poisoning”).
This initially results in a localized inflammatory reaction in the lungs, which leads to the destruction of the tissue and ultimately to a lung abscess. The abscess usually empties via the adjacent small airways (bronchi) and the affected person coughs up the contents. What remains is a cavity containing air and liquid. This usually heals completely and there are usually only small scars.
Lung abscess: Anaerobic and aerobic bacteria as causes
The inhaled bacteria are often species that can multiply well without oxygen. They are called anaerobes. These include, for example:
- Peptostreptococci
- Prevotella
- Bacteroides
- Fusibacteria
Bacteria that have not entered the lungs through inhalation are less likely to cause a lung abscess. These are usually not anaerobes, but aerobes – in other words, these pathogens require oxygen for their growth. They can also cause pneumonia without a lung abscess. Representatives of these aerobic bacteria are, for example:
- Staphylococci
- Streptococci
- Klebsiellen
- Haemophilus
- Legionella
- Pseudomonas
Sometimes both anaerobic and aerobic types of bacteria are involved in lung abscesses – a mixture of pathogens can therefore be detected in the lungs.
Lung abscess – rarer causes
In people with a weakened immune system, other, rarer types of bacteria, fungi or parasites are often the cause of lung abscesses. Examples are:
- Nocardia
- Actinomycetes
- atypical mycobacteria
- Fungi: Aspergillus, Cryptococcus neoformans, Histoplasma capsulatum
- Parasites: unicellular microorganisms such as amoebae, worms or lung flukes (in tropical regions)
Risk factors for lung abscesses
There are also some risk factors that increase the likelihood of a lung abscess. They increase the risk of a person accidentally inhaling secretions containing bacteria and these entering the lungs. For example:
- a weakened immune system
- Drug use: Alcohol, other drugs – they often cloud consciousness
- Drowsiness, for example due to anesthesia or sedatives
- Unconsciousness
- Neurological diseases associated with swallowing disorders
Symptoms: Lung abscess often develops slowly
A lung abscess usually develops gradually over weeks or months if anaerobic bacteria are involved in its development. If, on the other hand, aerobic bacteria are the cause, the symptoms often set in suddenly and the illness is acute – similar to pneumonia, which is caused by bacteria.
The symptoms of lung abscesses are often uncharacteristic and can also occur in many other diseases. The following signs are possible:
- Cough with sputum (productive cough), sometimes the sputum is mixed with blood and pus, it has a foul odor or taste
- sometimes chest pain
- Fever, chills
- Sweating, especially at night
- Tiredness and fatigue
- Reduced physical performance
- Loss of appetite, weight loss
Lung abscess: Diagnosis at the USZ
The first step in diagnosing a lung abscess is to discuss the patient’s medical history with us (anamnesis). For example, the following questions are important:
- What exactly are your symptoms, e.g. cough, sputum, fever?
- When did you first notice the symptoms – hours, days, weeks ago?
- How intense are the complaints?
- Are there situations in which the symptoms intensify?
- Do you have any known underlying illnesses, such as infections, gingivitis, periodontitis or neurological diseases that lead to impaired consciousness?
- Do you suffer from swallowing disorders?
- Have you traveled abroad, for example to tropical regions?
- Are you taking any medications? If yes: Which and since when?
- Do you use drugs (alcohol, illegal drugs)?
We can already draw initial conclusions about the cause of your complaints from your answers. This is followed by a physical examination. For example, we listen to the lungs with a stethoscope and can detect unusual lung noises, such as rales. Weakened breath sounds can also be an indication of a lung abscess. We also determine the body temperature.
Further examinations for suspected lung abscess
- X-ray examination of the chest (chest X-ray) – the lung abscess or cavities can be seen on the images.
- Computed tomography (CT): An X-ray examination that provides detailed cross-sectional images of the lungs. This enables us to detect air pockets in the lungs, but also to differentiate between other diseases such as lung cancer or tuberculosis.
- Blood test: e.g. determination of inflammation parameters such as C-reactive protein (CRP) or white blood cells, detection of antibodies against certain pathogens.
- Examination of the sputum (sputum analysis): We examine the sputum for bacteria, fungi and parasites.
- Bronchoscopy: An endoscopic examination of the lungs and bronchi, during which we can remove tissue and bronchial fluid at the same time. We then analyze these in the laboratory for pathogens.
It is important to find the pathogen causing the lung abscess – because this plays an important role in choosing the right treatment.
Lung abscess: prevention, early detection, prognosis
You cannot really prevent a lung abscess. There are also no special measures for early detection. Loss of consciousness is often involved when a person accidentally inhales secretions (aspirates in technical terms), which can also occur with high alcohol consumption or drug abuse. This is where those affected can start. You should also have neurological diseases, which are often accompanied by swallowing disorders, treated by a doctor. Good strategies for a strong immune system are: A healthy diet, plenty of exercise, avoiding inhalation of noxious substances such as cigarette smoke, little alcohol and little stress.
Course and prognosis of lung abscess
In around 90 percent of patients, the lung abscess heals after treatment with antibiotics. About ten percent require further treatment – but surgical interventions are extremely rare. The prognosis and course are therefore good for most patients.
Nevertheless, lung abscesses can lead to a number of complications, for example:
- Aspergilloma: Residual cavities may remain in the lungs in which mold fungi (aspergilli) colonize.
- Pleural empyema (pyothorax): The lung abscess breaks through into the pleural cavity and pus accumulates inside the pleura.
- Blood poisoning (sepsis) – the bacteria spread via the bloodstream to other organs, which is life-threatening. Sepsis must be treated immediately.
- Embolisms – due to the inflammation, the pulmonary vessels become blocked
Lung abscess: treatment usually with antibiotics
Bacteria usually cause lung abscesses. There are effective drugs that kill the germs – antibiotics. We usually administer them as an infusion in higher doses via the vein. If the lung abscess is less pronounced, you can also take the antibiotics in tablet form. The medication must be administered or taken over a longer period of time, around three to six weeks. The reason for the prolonged use: If not all pathogens are eliminated, they can multiply again. Then there is a risk of relapse (recurrence).