Definition
Pneumonia is an acute or chronic inflammation of the lung tissue (pneumonia). The inflammation can be limited to either the alveoli (alveolar pneumonia) or the lung support structure (interstitial pneumonia). Of course, mixed forms can also occur.
If the inflammation takes place predominantly in the alveoli, it is often referred to as typical pneumonia, which is characterized by its classic symptoms such as sudden onset of fever, coughing with sputum and shortness of breath. If the inflammatory process takes place more in the supporting and connective tissue of the lungs, on the other hand, it is called atypical pneumonia, in which the classic symptoms may be less pronounced or not at all. A pneumonia without fever, also known as “cold pneumonia”, can therefore certainly occur. Due to its atypical course, it is not always easy to recognize it directly and therefore it is not less dangerous than classical pneumonia.
Causes
Pneumonia is generally caused by various pathogens, including bacteria, viruses and fungi. Which pathogen is most likely to cause pneumonia depends on where the pneumonia was acquired, i.e. outpatient in a domestic environment or nosocomial in hospital, e.g. in the context of another treatment measure where an inpatient stay was necessary.
In addition, the typical pathogens have different sites of inflammation. Some pathogens are more likely to cause inflammation in the alveoli, others in the lung support tissue. The most common pathogen causing outpatient pneumonia is the bacterium Streptococcus pneumoniae (pneumococcus).
The most common pathogens of nosocomial pneumoniae are the bacteria Escherichia coli, Staphylococcus aureus or Pseudomonas aeruginosa. Ambulantly acquired atypical pneumonia is classically caused by bacteria such as mycoplasma, chlamydia or viruses (e.g. influenza). Nosocomial atypical pneumonia is most commonly caused by bacteria such as legionella (Legionella pneumoniae) or fungi (Aspergillus fumigatus, Pneumocystis jirovecii). Other causes of pneumonia can also be parasites, inhaled toxins or aspiration (inhalation) of gastric juice/acid.
Diagnosis
If pneumonia is suspected, the diagnosis should be confirmed by a thorough physical examination. This is not always easy, as atypical pneumonia without fever often does not show classic, pronounced findings. When listening to the lungs, one typically perceives rales and increased breathing sounds.
In addition, a muffled tapping sound can often be heard when tapping the back. In this case, examination of the blood for signs of infection and inflammation (e.g. white blood cells, C-reactive protein) and pathogens (blood cultures) can help. In addition, the pathogen can be determined from saliva or lung secretion samples. In particularly unclear cases, a tissue sample (biopsy) from the lung tissue may also be necessary to determine the exact clinical picture. In addition, an x-ray of the chest is often taken, in which, for example, shadows in the lung can provide further indications of a possible existing pneumonia.
