What is pneumococcal disease?
Pneumococcal disease refers to illness caused by infection with the bacterium Streptococcus pneumoniae (sometimes shortened to Strep. pneumoniae). These bacteria are also known as pneumococci.
Pneumococci exist in several varieties (strains or ‘serotypes’) and are a cause of serious infections, including pneumonia, ear infections and meningitis (infection of the membrane surrounding the brain). Pneumococcal disease is believed to result in millions of deaths worldwide each year, especially affecting young children in developing countries. There is a very high incidence of pneumococcal disease among indigenous Australians.
Infection with the pneumococcus bacterium can cause:
- otitis media (inflammation of the middle ear and ear drum);
- sinusitis (inflammation of one or more sinuses);
- pneumonia (inflammation of the lungs);
- bacteraemia (presence of bacteria in the bloodstream); and/or
- meningitis (inflammation of the membranes that surround the brain and spinal cord - the meninges).
Less commonly, pneumococcus can infect other areas of the body, for example, resulting in septic arthritis (infection of a joint) and osteomyelitis (infection of bone, particularly affecting the long bones in children).
(Pneumococcal disease is not to be confused with meningococcal disease, which is caused by a different bacterium and results in meningitis outbreaks and septicaemia, most commonly in children and young adults during winter and early spring.)
Risk factors for pneumococcal disease
Pneumococcal disease most commonly affects:
- older adults, over 65 years of age;
- indigenous Australians aged over 50 years;
- young children under 2 years of age;
- people whose immune system is not working properly, including those who have had their spleen removed; and
- people who have an underlying medical condition such as cancer, diabetes or kidney disease.
How Streptococcus pneumoniae causes pneumococcal disease
The bacterium that causes pneumococcal disease - Streptococcus pneumoniae - can be found relatively commonly in the upper respiratory tract (e.g. the nose and throat) of healthy people, particularly young children, without causing any adverse effects.
S. pneumoniae can spread among people when they are in close contact. Tiny droplets of fluid from the nose or mouth of someone carrying the infection are transferred to another person, for example, when coughing, sneezing or kissing, or by babies sharing toys.
The bacterium will not cause pneumococcal disease in every person who is exposed to it; in fact this outcome is uncommon among generally healthy people. However, illness is more likely to occur in the very young, the old and the unwell. In these people, the body's defence mechanism - the immune system - may not be able to keep the bacteria at bay. If this occurs, the bacteria can then invade the tissues locally and cause illnesses such as otitis media and sinusitis, or spread down the respiratory tract to cause pneumonia, or they can enter the blood stream (bacteraemia) and cause invasive pneumococcal disease such as meningitis or septic arthritis
The symptoms depend on which area of your body is affected, and can include the following.
- Otitis media: ear pain; reduced hearing; fever; and irritability.
- Pneumonia: breathing difficulties (more rapid breathing, shortness of breath); cough; chest pain; low energy; lack of appetite; and headache.
- Meningitis: neck stiffness; fever; headache; nausea; and vomiting.
Your doctor will not be able to diagnose pneumococcal disease based on a physical examination alone. Your signs and symptoms may point to a diagnosis of meningitis or pneumonia, but various different bacteria and viruses can cause these conditions. If you have pneumonia, a chest X-ray cannot identify the organism causing your infection, but it will give an indication of inflammation and infection in your lungs by showing an accumulation of fluid or debris in the air spaces.
A definitive diagnosis of pneumococcal disease can only be made by identifying S. pneumoniae in a blood sample or a sample of cerebrospinal fluid (CSF), or by doing special tests on other body fluids such as a sputum (phlegm) or urine sample.
All of these samples are tested in a pathology laboratory. However, because invasive pneumococcal disease is serious, doctors may send the person straight to hospital and the tests may be done there.
In a person who has acute sinusitis or otitis media that may be caused by pneumococcus, the doctor will usually start treatment that covers the possibility of pneumococcal disease, because samples to identify the cause are not easily obtained.
Pneumococcal disease requires treatment with antibiotics. However, of concern is the increase in resistance to antibiotic treatment displayed by some S. pneumoniae bacteria. Therefore, in a person who is showing symptoms of pneumococcal disease, doctors will often test the bacteria that is present in the person's blood, CSF or sputum sample against various antibiotics in the laboratory (antibiotic sensitivity testing).
Because pneumococcal disease can cause severe illness, doctors will usually not wait for test results but will start treatment with antibiotics immediately. However, the antibiotic can be changed when sensitivity results are available if this test suggests resistance to the initial choice.
In many mild or uncomplicated infections, such as sinusitis or otitis media due to S. pneumoniae, the infection may resolve spontaneously. Your doctor will assess you and make a clinical decision as to whether antibiotics are necessary.
Treatment of pneumococcal disease can also include medicines to relieve pain, fluids to manage dehydration, and rest.
Vaccines are available to help prevent pneumococcal disease. Pneumococcal vaccination is part of the National Immunisation Program and is also free to Australians who are at high risk of pneumococcal disease and its complications.
Approximately 90 different strains (serotypes) of S. pneumoniae have been found so far, and while current vaccines don't offer protection against all of them, they do protect against the most commonly encountered disease-causing serotypes.
Two types of pneumococcal vaccine are available in Australia.
The 13-valent pneumococcal vaccine
Prevenar 13 vaccine protects against 13 serotypes of pneumococcus, particularly those strains that cause the majority of serious disease in young children. This vaccine has been available since July 2011 and is free as part of the National Immunisation Program for use in babies and children. A course of 3 injections is usually given at 2, 4 and 6 months of age. After this, no further doses are usually required, except for Aboriginal and Torres Strait Islanders in high-risk areas, who may have another dose at 12-18 months, or infants at higher than normal risk, who may have another dose at 12 months. This schedule may vary if the timing of the first vaccination is delayed. Your doctor will be able to advise you of your baby's requirements on an individual basis. If your child is considered to be at higher than normal risk of pneumococcal disease, your doctor will advise you of your child's future vaccination needs following the initial vaccine course.
Prevenar 13 can also be given to adults 50 and over.
Side effects of Prevenar 13 include fever and reaction at the injection site.
The 23-valent pneumococcal vaccine
Pneumovax 23 vaccine helps protect against 23 serotypes of pneumococcus and is recommended in the National Immunisation Program Schedule to be given to all adults aged 65 years or older, and Aboriginal and Torres Strait Islander people at 15 years (if medically at risk) and when aged 50 years or older. It is also recommended for children medically at risk, at 4 years of age.
Some people are at higher risk of serious complications from pneumococcal infection and will need to be re-vaccinated after 5 years — ask your doctor whether you need this booster dose. People with a medical condition putting them at high risk may need to be vaccinated when their condition is diagnosed and not wait until age 65.
Side effects of Pneumovax 23 include reaction at the injection site and fever.
Your doctor can talk to you about your risk or your child's risk of pneumococcal disease, and discuss the vaccination schedule that you or your child may require.
2. Pneumococcal pneumonia (revised Nov 2014). In: eTG complete. Melbourne: Therapeutic Guidelines Limited; 2016 Mar. http://online.tg.org.au/complete/ (accessed Aug 2016).
3. Australian Government Department of Health and Ageing, National Health and Medical Research Council. The Australian Immunisation Handbook, 10th Edition. 4.13 Pneumococcal disease (updated Apr 2016). http://www.immunise.health.gov.au/internet/immunise/publishing.nsf/Content/Handbook10-home~handbook10part4~handbook10-4-13 (accessed Aug 2016).