Lung Infections

What is a Lung Infection?

Lung Infections

We all breathe in about 5 litres of air per minute at rest and this air often contains particles containing viruses and bacteria. These viruses and bacteria can infect many parts of the respiratory system becoming a lung infection.  They often begin in the nose and throat, descend to involve the trachea, smaller airways and alveolar or sponge part of the lungs.  Infected alveoli can spill over into the pleural cavity, which is the space between the lungs and the chest wall normally containing a very small amount of fluid.

We can recover from these infections quickly but occasionally the contagion can overwhelm our immune system and spill over into the blood and cause bacteraemia.  Infections can occur rapidly and are called acute or can persist long term and are referred to as chronic.

Infections create a battle between our immune system and the virulence of the invading organism.  Our immunity is dependent on our nutrition, our past exposure to bugs and our capacity to develop antibodies to the invading bugs before they overwhelm us.

Most infections take a while to build up.  Initially you might have a runny nose, sore throat or feel a bit hot and sweaty.  Then you may get a fever, worsening sore throat, cough, sputum or phlegm production.  If the bug is particularly nasty or your immune system is run down, the bug can multiply rapidly and overcome your immune defences, leading to a potentially serious infection which can spill over into the blood stream (septicaemia) or pleural space (pleurisy and empyema).

Viral infections usually settle quickly, are relatively minor and require no treatment other than Paracetamol.  The influenza virus is an exception and usually begins with a runny nose, sore throat, cough, muscle aches and pains, with a high fever.  Anti Flu drugs can stop this illness quickly if they are administered early in the infection.  This usually requires rapid identification of the virus with a swab taken from the back of the throat and processed quickly in the laboratory.

Bacterial infections are different and can be more serious. They usually are associated with a nasty cough and dirty sputum production and require prompt administration of antibiotics.  Antibiotics which cover most bacteria causing pneumonia include Doxycycline, Roxithromycin and Clarithromycin for atypical infections and Amoxycillin, or Cephalexin for the typical bacteria causing pneumonia.  If the infection is overwhelming with low blood pressure, confusion, kidney failure and low oxygen levels, or if the patient is elderly and has underlying other medical problems, hospitalisation is often necessary.