Pneumonia is infection of the lungs. The infection is in the lung tissue and the tiny air sacs in the lungs where the blood receives oxygen from air that is breathed in. It is extremely common and can range from a mild illness to a fatal one, especially if the patient is already sick or in hospital. Pneumonia is not a single disease but refers to many different infections, each caused by a different micro-organism.
The most common cause of pneumonia in people aged five to 35 years is mycoplasma. In older adults, the most common causes are bacteria (e.g. pneumococci), which are also a common cause in young infants.
Bacterial and Mycoplasmal Pneumonia
Mycoplasma pneumonia usually starts with a dry cough and tiredness, followed occasionally by a rash and phlegm production. Although the symptoms are usually mild, they can last for several weeks.
Pneumococcal pneumonia gives the common symptoms described above, such as the cough, fever and pain on the side of the affected lung. Streaks of blood may be seen in the phlegm.
The bacterium Legionella pneumophila causes the pneumonia 'Legionnaire's disease'. It spreads through water and can contaminate air-conditioning systems, which results in outbreaks of the disease. The infection begins with aches and pains, fever and headache, followed by a cough that eventually produces phlegm. Although the disease is usually mild, it can be severe, with extreme breathlessness, diarrhea and confusion. About 20% of people who develop this disease die.
The bacterium Haemophilus influenzae does not cause flu (which is caused by the influenza virus); instead it is a major cause of pneumonia in children below the age of six years. The pneumonia usually begins with sneezing and a runny nose, and then develops into the common symptoms described above. In addition, some fluid commonly develops around the lung, called a 'pleural effusion'. However, the 'type b' strain of the bacterium can cause severe illness such as meningitis and epiglottitis.
Many viruses can cause pneumonia, including influenza, herpes, measles and chickenpox. The symptoms vary according to the type and severity of infection, but usually there is a cough, often with phlegm, fever and chills.
Fungi can cause pneumonia, but they are relatively rare except in people who have suppressed immune systems (such as those with AIDS).
The best test is to take some phlegm, examine it under the microscope and try to cultivate the organism that is causing the infection. This helps establish which antibiotic the bacterium is susceptible to. This is important (especially for pneumonias acquired in a hospital) because many bacteria are becoming resistant to antibiotics.
Most viral pneumonias are not treated with drugs that kill the virus: your body's immune system will usually do the job. However, in some cases of chickenpox and herpes an antiviral drug may be used early in the course of the disease.
The common symptoms of pneumonia include fever.
The pain of lobar pneumonia often begins as a general sense of pressure and aching, usually localized to one side of the chest. The pain begins around the time of the chills heralding the onset of the infection. Later, as the process affects the pleura (tissues around the lung), pleuritic pain develops. Patients with atypical pneumonia or bronchopneumonia may complain of a central burning sensation provoked by coughing.
Viral pneumonia often produces a dry cough at the beginning. The cough usually becomes worse and produces a small amount of mucus. Mycoplasma pneumonia is associated with a cough that tends to come in violent attacks, but produces only sparse whitish mucus.
A cough with phlegm is a common symptom of pneumonia. Bacterial pneumonia involves a cough that usually produces rust-colored or greenish mucus. Viral pneumonia often produces a dry cough at the beginning, which usually becomes worse and produces a small amount of mucus.
A chest X-ray is nearly always taken to confirm or rule out a pneumonia diagnosis.
October, 2014: A three-year study of 524 adults over the age of 85 and published in the Journal of Dental Research has found that patients who wear dentures during sleep are at 2.3 times higher risk for developing pneumonia than those who remove them. The researchers also found that overnight denture wearing increased levels of tongue and denture plaque, gum inflammation, a positive culture for Candida albicans, and bad breath.
Dentures are covered in thin layers of bacteria known as biofilms, which can then be breathed into the lungs. Two good methods of disinfecting dentures are to put them in a microwave for three minutes (unless they contain metal), or soak them in a solution of 2% chlorhexidine gluconate, a germicidal mouthwash, for 10 minutes.
In a clinical study of 124 patients hospitalized with chronic bronchitis, pneumonia, bronchopneumonia, bronchiectasis, or pulmonary abscess, those receiving bromelain orally showed a decrease in the volume and pus-like quality of the sputum. [J Clin Invest 1985;75: pp.456-61]
Pneumonia caused by bacteria and mycoplasma is generally treated with antibiotics. The type of antibiotic used depends on which organism has caused the infection. If the infection is severe, and especially in very young and old people, the pneumonia may need to be treated in hospital with antibiotics and fluids given into a vein, and extra oxygen through a mask.
Fungal pneumonias are treated with specific antifungal drugs.