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Pneumococcal infections

Page last reviewed: 13/07/2011

Pneumococcal infections are acute infections caused by the Streptococcus pneumoniae (S. pneumoniae) bacterium. There are more than 90 different strains of S. pneumoniae bacteria, which are known as serotypes.

S. pneumoniae enters the human body through the nose and mouth.

Types of pneumococcal infection

Pneumococcal infections usually fall into one of the following two categories.

  • Non-invasive pneumococcal infections. These occur outside the major organs or the blood and tend to be less serious.
  • Invasive pneumococcal infections. These occur inside a major organ or the blood and tend to be more serious.

The two types of infection are described in more detail below.

Non-invasive pneumococcal infections

Non-invasive pneumococcal infections include the following.

  • bronchitis: an infection of the bronchi, which are the tubes that run from the windpipe down into the lungs
  • otitis media: an infection of the middle ear, which usually affects children under the age of 10
  • sinusitis: an infection of the sinuses, the small air-filled cavities behind the cheekbones and forehead

Invasive pneumococcal infections

Invasive pneumococcal infections include the following.

  • bacteraemia: a relatively mild infection of the blood
  • septicaemia (blood poisoning): a more serious blood infection
  • osteomyelitis :infection of the bone
  • septic arthritis: infection of a joint
  • pneumonia: infection of the lungs
  • meningitis: infection of the meninges, which are the protective membranes surrounding the brain and spinal cord

How common are pneumococcal infections?

It is difficult to estimate the exact number of cases of non-invasive pneumococcal infections that occur each year. This is because infections often clear up within a few days and many people do not visit their GP. However, they are thought to be quite common.

Pneumonia is the most common type of invasive pneumococcal infection.

Other types of invasive pneumococcal infections, such as bacteraemia, are less common.

Meningitis is the most serious type of invasive pneumococcal infection and is also the rarest. It is estimated that only 1 person in every 100,000 will develop meningitis in any given year.

People with a weakened immune system are most at risk of catching a pneumococcal infection. This may be because:

  • they have a serious health condition, such as HIV or diabetes, that weakens their immune system
  • they are having treatment or taking medication that weakens their immune system, such as chemotherapy

Other at-risk groups include:

  • babies and young children under two years of age
  • adults over 65 years of age
  • people who misuse alcohol

See Pneumococcal infections - causes for a full list of the groups who are at risk of developing a pneumococcal infection.

Cases of invasive pneumococcal infection usually peak in the winter during December and January.

Pneumococcal infections can be treated with antibiotics.

Pneumococcal vaccines

There are two different types of pneumococcal vaccine:

  • pneumococcal conjugate vaccine (PCV), which is given to all children under two years of age as part of the childhood vaccination programme
  • pneumococcal polysaccharide vaccine (PPV), which is given to people aged 65 years or over and others who are at high risk

The PCV protects against 13 types of S. pneumoniae bacteria and the PPV protects against 23 types. It is thought that the PPV is around 50-70% effective at preventing more serious types of invasive pneumococcal infection.

See Pneumococcal vaccination - how it works for more information about these two types of vaccine and Pneumococcal vaccination - when it is used for further details of the high-risk groups that should receive the vaccine.


Non-invasive pneumococcal infections are usually mild and go away without the need for treatment.

The outlook for pneumonia in people who are otherwise healthy is good, but the infection can lead to serious complications in people who are very young, very old or have another serious health condition.

However, due to the introduction of the PCV in 2008, the number of people dying from complications that arise from pneumonia has fallen.

The outlook for other types of invasive pneumococcal infections such as bacteraemia is generally good, although there is about a 1 in 20 chance that bacteraemia will trigger meningitis as a secondary infection.

The outlook for meningitis is poor. One person in ten with the condition will die and one in four will experience complications such as hearing loss, which may be permanent.

Multidrug-resistant Streptococcus pneumoniae (MDRSP)

During the 1990s, the increasing levels of S. pneumoniae that had developed a resistance to three or more types of antibiotics was a major concern. These types of bacteria are known as multidrug-resistant Streptococcus pneumoniae (MDRSP).

One study carried out during that time estimated that as many as one case of pneumococcal infection in five was associated with MDRSP.

MDRSP is a real concern because any infection caused by these resistant bacteria is challenging to treat and carries a higher risk of causing complications.

Thankfully, the introduction of two pneumococcal vaccines (PCV and PPV) led to a drop in MDRSP. Fewer cases of infection meant that antibiotics were used less frequently, and the less an antibiotic is used to kill bacteria the smaller the chance the bacteria will develop resistance to that antibiotic.

However, data from the UK for the years 2008-2009 suggest that levels of MDRSP are starting to increase again, particularly a strain known as serotype 19A, which is not covered by the PCV.

The ability for bacteria to become resistant to antibiotics is the reason why GPs are becoming increasingly reluctant to prescribe antibiotics for mild infections.

Page last reviewed: 13/07/2011

If you have a pneumococcal infection your symptoms will vary depending on the type of infection you have. Some common symptoms include:

  • a high temperature (fever) of 38°C (100.4°F) or above
  • chills
  • sweats
  • aches and pains
  • headache
  • a general sense of feeling unwell

When to seek medical advice

You should contact your GP as soon as possible if you:

  • have a constant high temperature that lasts for more than three days
  • cough up mucus that is streaked with blood
  • develop rapid breathing (more than 30 breaths a minute) or chest pains
  • become drowsy or confused
  • experience shortness of breath or other breathing difficulties

You should also contact your GP as soon as possible if:

  • your child is under two years of age and they develop a high temperature
  • your child is over two years of age and their symptoms persist for more than three days

You should also see your GP if you have any of the risk factors that make you more vulnerable to developing a pneumococcal infection. See Pneumococcal infection - causes for more information about risk factors.

When to seek emergency medical advice

The most serious type of pneumococcal infection is bacterial meningitis, which requires immediate admission to hospital for emergency treatment.

Bacterial meningitis has a number of early warning signs that can occur earlier than the other symptoms.

These are:

  • pain in the muscles, joints or limbs, such as in the legs or hands
  • shivering or unusually cold hands and feet
  • blue lips and pale or blotchy skin

As the condition gets worse it may cause:

  • drowsiness
  • confusion
  • seizures or fits
  • an inability to tolerate bright lights, known as photophobia (this is less common in young children)
  • a stiff neck (also less common in young children)
  • a rapid breathing rate
  • a blotchy, red rash that does not fade or change colour when you place a glass against it

The symptoms of bacterial meningitis are different in babies and young children. Possible symptoms include:

  • becoming floppy and unresponsive or stiff with jerky movements
  • becoming irritable and not wanting to be held
  • unusual crying

You should dial 999 immediately to request an ambulance if you suspect that you or someone you know has bacterial meningitis.

Page last reviewed: 13/07/2011

Streptococcus pneumoniae

There are more than 90 different strains of Streptococcus pneumoniae (S. pneumoniae) and some are much more likely to cause serious infection (virulent) than others.

Each strain of bacteria is classified by the type of complex sugar molecules that make up the outer shell of the bacteria.

Exactly how the outer shell is constructed is one factor that determines how virulent each strain is. Some strains have a weak and flimsy outer shell, which means the bacteria can be easily killed by infection-fighting white blood cells.

Other strains have a very tough outer shell, which makes the bacteria resistant to white blood cells and likely to cause a more serious infection.

It is thought that 8-10 strains are responsible for two-thirds of cases of serious infections in adults and most cases in children.

S. pneumoniae enter the human body through the nose and mouth, and an infection can be spread in the same way as a cold or the flu. This can be through:

  • direct contact, for example, when someone sneezes or coughs, tiny droplets of fluid that contain the bacteria are launched into the air and can be breathed in by others
  • indirect contact, for example, if infected droplets of fluid are transferred from someone's hand to a door handle, someone else who touches the handle may become infected with the bacteria if they then touch their mouth or nose

It is important to emphasise that pneumococcal infections are far less contagious than a cold or the flu. This is because most people's immune systems are able to kill the bacteria before they have the opportunity to cause an infection.

Outbreaks of pneumococcal infections can sometimes occur in environments where there are many people who have a poorly functioning immune system, such as in children's nurseries, care homes for the elderly and shelters for people who are homeless.

Risk factors

In most cases, S. pneumoniae bacteria do not cause a problem because the immune system prevents them moving from the throat to other parts of the body.

However, in people with a weakened immune system, either due to their age or general health, the bacteria can move from their throat to other parts of their body, such as the lungs, the blood or the brain. If this occurs, a more serious infection can develop.

People who are particularly at risk from developing a pneumococcal infection are listed below.

  • children under two years of age
  • adults over 65 years of age
  • those with a weakened immune system as a result of a health condition such as HIV or AIDS
  • those who are receiving medical treatment that is known to weaken the immune system, such as chemotherapy or corticosteroids
  • those with a history of spleen disease or dysfunction (the spleen is an organ that filters the blood and plays an important role in fighting infection)
  • those with a chronic respiratory disease, such as chronic obstructive pulmonary disease (COPD)
  • those with coronary heart disease or who have previously had a heart attack
  • those with chronic kidney disease or chronic liver disease
  • those with diabetes who need to take insulin
  • those who wear a type of hearing aid called a cochlear implant (people who use these have a slightly increased risk of developing meningitis, but the reasons for this are unclear)
  • those who are addicted to alcohol or regularly misuse alcohol (alcohol misuse is known to weaken the immune system)
  • those who are currently infected by the influenza virus (this applies to both seasonal flu and swine flu)
  • those who smoke cigarettes or other tobacco products
  • those who are living in poverty (many of the factors related to poverty, such as poor diet and living in unhygienic and overcrowded environments, increase a person's risk of developing a pneumococcal infection)
  • Those with spinal damage that has caused their cerebrospinal fluid (a fluid that surrounds the brain and spine) to leak

Page last reviewed: 13/07/2011

Several different tests can be used to diagnose pneumococcal infections. The tests you have will depend on your symptoms.

Some of the tests that may be used are outlined below.

Physical examination

If a pneumococcal infection is suspected, your GP will listen to your chest with a stethoscope. The fluids that are produced during an invasive pneumococcal infection often cause a distinctive crackling sound.

Blood test

You may have a blood test to check for the presence of bacteria. A high number of infection-fighting white blood cells may indicate the presence of an infection. The blood sample can be sent to a laboratory so the bacteria that caused the infection can be identified.


X-rays may be able to highlight the presence of fluid in the lung, which would indicate a lung infection. An X-ray uses radiation to produce images of the inside of the body.

Blood pressure test

You may have a blood pressure test because a serious infection can often lead to a decrease in blood pressure. 

Lumbar puncture test

A lumbar puncture test involves taking a sample of cerebrospinal fluid (the fluid that surrounds the brain and spine) from the base of your spine and checking it for the presence of bacteria. If the sample contains infection-fighting white blood cells and/or bacteria, it may indicate that you have meningitis.

Urinary antigen test

A urinary antigen test is a relatively new type of test that can be used to help diagnose a pneumococcal infection.

It involves taking a urine sample and then carrying out a technique known as an immunochromatographic assay. This is able to detect the distinctive protein molecules that make up the outer shell of the S. pneumoniae bacteria.

Page last reviewed: 13/07/2011

Non-invasive pneumococcal infections

Non-invasive pneumococcal infections, such as sinusitis or bronchitis, will usually clear up within a week without the need for treatment.

Drinking plenty of fluids, getting plenty of rest and taking over-the-counter painkillers, such as paracetamol, should help to relieve your symptoms.

For more information about treatment for specific types of pneumococcal infections see the Health A-Z topics about:

Invasive pneumococcal infections 

If you have an invasive pneumococcal infection, such as pneumonia, a decision will be made about whether you are well enough to be treated at home or need to be admitted to hospital.

Most GPs use a scoring system, known as the CRB-65 score, to assess the potential seriousness of a case of pneumonia.

  • C stands for confusion: if you are mentally confused you may have a more serious infection.
  • R stands for respiratory rate: your respiratory rate is how many breaths you take in a minute. More than 30 breaths a minute may be a sign that your lungs are not working properly.
  • B stands for blood pressure: low blood pressure can be a sign of a more serious infection.
  • 65 indicates whether your are 65 years of age or over: older people are more vulnerable to the effects of infection.

Each of the above criteria is given a score of either 0 or 1 depending on whether or not it is applicable. This scoring system is explained below.

  • A CRB-65 score of 0 means you have a low risk of complications and can usually be treated at home.
  • A CRB-65 score of 1-2 means you have a medium risk of developing complications and you should have a same-day assessment by an expert in treating pneumonia. Depending on the results of the assessment, you may be treated at home or you may need to be admitted to hospital.
  • A CRB-65 score of 3 or more means you have a high risk of developing complications and you should be admitted to hospital for urgent treatment.

Hospital admission is also recommended for:

  • any type of invasive pneumococcal infection that has developed in a baby or child less than two years of age
  • all cases of suspected meningitis

Treatment at home

If you are being treated at home, you will usually be prescribed a seven-day course of antibiotics. An antibiotic called amoxicillin is the preferred choice. If you are allergic to amoxicillin, alternative antibiotics such as doxycycline can be used.

The most common side effects of the antibiotics used to treat pneumonia are:

  • nausea (feeling sick)
  • vomiting
  • diarrhoea

These side effects are usually mild.

Sometimes, doxycycline can make your skin more sensitive to the effects of sunlight. Therefore, you should minimise your exposure to direct sunlight and avoid using sun lamps and sun beds when taking doxycycline.

It is very important that you finish your course of antibiotics, even if you start to feel better. Not completing the full course of antibiotics could cause the pneumonia to return.

Treatment at hospital

If your symptoms are moderate, you can usually be treated with antibiotic tablets.

If your symptoms are severe, you will usually be given antibiotics through a drip into your arm. You may also be given fluids to stop you becoming dehydrated, and oxygen to help you breathe.

Depending on how well you respond to treatment, it may be possible to switch from a drip to antibiotic tablets after a few days.

Most people who are treated in hospital require a seven-to-ten-day course of antibiotics. The length of time it will take before you are well enough to return home will depend on your general state of health and whether you experience a more serious type of pneumococcal infection, such as meningitis. 

Follow up

It is usually recommended that you attend a follow-up examination six weeks after the start of your symptoms. This is to check that the infection has not caused any serious or permanent damage to the affected parts of your body, such as your lungs.

The follow-up examination usually involves taking a chest X-ray so the state of your lungs can be assessed.

Page last reviewed: 13/07/2011

Preventing the spread of infection

You can help to prevent the spread of a pneumococcal infection by taking some simple hygiene precautions. These include:

  • washing your hands regularly and thoroughly, particularly after touching your mouth and nose and before handling food
  • coughing and sneezing into a tissue, throwing it away immediately and washing your hands
  • not sharing cups or kitchen utensils with others

Pneumococcal conjugate vaccine (PCV)

All children under the age of two should routinely receive the pneumococcal conjugate vaccine (PCV) as part of their childhood immunisation schedule.

The first dose of PCV is usually given when a child is two months old, with a second dose given four months later when the child is 6 months of age.

The PCV is entirely safe, although about one child in 10 will experience some redness and swelling at the site of the injection and symptoms of a mild fever. However, these side effects will pass quickly.

You should speak to your GP if you are not sure whether your child has received their PCV.

Pneumococcal polysaccharide vaccine (PPV)

If you are in one of the high-risk groups for developing a pneumococcal infection (see Pneumococcal infections - causes), contact your GP surgery to arrange a vaccination.

Healthy adults usually only need one dose of PPV. However, those with weakened immune systems or spleen disorders may need additional booster doses. Your GP will be able to advise you about this.

After you have had the PPV you may experience some pain and inflammation at the site of the injection. This should only last for one to three days. Less commonly, some people report the symptoms of a mild fever. Again, this should pass quickly.

See the Health A-Z topic about Pneumococcal vaccination for more information and advice.


There is an increasing body of evidence to suggest that people who drink an excessive amount of alcohol are at greater risk of developing invasive pneumococcal infections.

Alcohol is known to suppress the immune system, the body's natural defence system that will attempt to prevent an invasive pneumococcal infection. Therefore, the best way to lower your risk of developing a pneumococcal infection is to ensure that you stick to the recommended daily amounts of alcohol.

For men, the recommended weekly limit of alcohol consumption is three to 21 standard drinks for men 14 for women. A standard drink of alcohol is equal to about half a pint of normal-strength lager, a small glass of wine or a pub measure (25ml) of spirits.

Speak to your GP if you are finding it difficult to moderate your alcohol consumption. Counselling and medication are available for people with an alcohol misuse problem.

See the Health A-Z topic about Alcohol misuse or more information and advice.


Smoking is the single biggest risk factor for developing an invasive pneumococcal infection in otherwise healthy adults.

Research has found that almost 60% of previously healthy people who develop an invasive pneumococcal infection are smokers.

It is not known exactly why smoking makes a person more vulnerable to an invasive pneumococcal infection. One theory is that the chemicals contained in tobacco smoke disrupt the normal workings of the immune system and make it less efficient.

As well as reducing your risk of developing an invasive pneumococcal infection, giving up smoking will help reduce your risk of developing other serious health conditions, such as cancer, heart disease and stroke.

If you decide to stop smoking, your GP will be able to refer you to a local smoking cessation service which will provide you with dedicated help and advice about the best ways for you to give up smoking. You can also call the National Smokers Quitline at 1850201203, or log on to www.quit.ie, or join our facebook page at www.facebook.com/hsequit for further support.

Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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