Streptococcal infections are any type of infection caused by the streptococcus ("strep") group of bacteria.
There are many different types of Streptococci bacteria, and infections vary in severity from mild throat infections to life-threatening infections of the blood or organs. Most streptococcal infections can be treated with antibiotics.
Streptococci are divided into two key groups:
- alpha-haemolytic – made up of two groups, including Streptococcus pneumoniae
- beta-haemolytic – made up of several groups, including Group A and Group B streptococci
This topic focuses on Group A and Group B beta-haemolytic streptococci. Read about pneumococcal infections for information on infections caused by Streptococcus pneumoniae.
Group A strep
Group A strep (strep A) are often found on the surface of the skin and inside the throat. They are a common cause of infection in adults and children.
They can be spread in droplets in the coughs or sneezes of someone with an infection, or through direct contact with an infected person or contaminated object.
Minor strep A infections
Most infections caused by strep A are unpleasant, but don't pose a serious threat to your health. These include:
- throat infections (pharyngitis or "strep throat") and tonsillitis – which can cause a sore throat, swollen glands and discomfort when swallowing
- impetigo – a skin infection that can cause sores, blisters and crusts to develop on the skin
- cellulitis – an infection of the deeper layers of the skin, which can cause affected areas to quickly become red, painful, swollen and hot
- a middle ear infection – which often causes earache, a high temperature (fever) and some temporary hearing loss
- sinusitis – an infection of the small cavities behind the forehead and cheekbones, which causes a blocked or runny nose and a throbbing pain in your face
- scarlet fever – an infection that causes a widespread, fine pink-red rash that feels like sandpaper to touch
Click on the links above for more information on these conditions.
You should see your GP if you have persistent or severe symptoms of a strep A infection, as they may recommend a short course of antibiotics.
Most people with a minor strep A infection will make a full recovery and experience no long-term problems, although there is a very small risk hat the infection could spread further into the body (known as an invasive infection) or lead to complications such as rheumatic fever if left untreated.
Invasive strep A infections
In rare cases, strep A bacteria can penetrate deeper inside the tissues and organs of the body, and become what's known as an invasive infection.
These infections are much rarer and usually affect certain groups of people, including babies, elderly people, people with diabetes, and people with weak immune systems (for example, because of cancer treatment or HIV).
Examples of invasive infections include:
- pneumonia – an infection of the lungs that causes persistent coughing, breathing difficulties and chest pain
- sepsis – an infection of the blood that causes a fever, rapid heartbeat and rapid breathing
- meningitis – an infection of the protective outer layer of the brain that causes a severe headache, vomiting, stiff neck, sensitivity to light and a distinctive blotchy red rash
- toxic shock syndrome – where bacteria release toxins into the blood, which can cause a sudden high fever, nausea and vomiting, diarrhoea, fainting, dizziness and confusion
- necrotising fasciitis – an infection of the deeper layers of the skin, fat and covering of the muscle (fascia), which can cause severe pain, swelling and redness of the affected area that can spread very quickly
Click on the links above for more information on these conditions.
You should seek immediate medical advice if you think you may have an invasive strep A infection, as you will need to be treated with antibiotics as soon as possible.
Although pneumonia is sometimes relatively mild, the overall outlook for more serious invasive strep A infections is poor. It's estimated that up to one in every four people who develop an invasive strep A infection will die from it.
Group B strep
Group B strep (strep B) usually live harmlessly inside the digestive system and in the vagina.
Strep B can sometimes cause urinary tract infections (UTIs), skin infections, bone infections, blood infections and pneumonia, particularly in vulnerable people, such as the elderly and those with diabetes.
Strep B in pregnancy
It's estimated that around one in every four pregnant women have strep B bacteria in their vagina and/or digestive system.
The bacteria can sometimes be passed on to the baby through the amniotic fluid (a clear liquid that surrounds and protects the unborn baby in the womb) or as the baby passes through the birth canal during labour.
Most babies exposed to strep B will be unaffected, but in around one in every 2,000 cases, they can become infected (see below).
A strep B infection during pregnancy can also cause miscarriage or stillbirth, but this is rare.
Strep B in newborn babies
As newborn babies have a poorly-developed immune system, strep B bacteria can quickly spread through their body, causing serious infections, such as meningitis and pneumonia.
The symptoms of a strep B infection in a newborn baby usually develop within the first few hours or days of giving birth, and include:
- being floppy and unresponsive
- poor feeding
- grunting when breathing
- an unusually high or low temperature
- unusually fast or slow breathing
- an unusually fast or slow heart rate
In some cases, a baby can pick up a strep B infection a few weeks or months after birth. It's not known exactly why this happens, but it's not related to infection during birth. Symptoms of a late-onset group B strep infection can include a fever, poor feeding, vomiting, and reduced consciousness.
You should seek immediate medical advice if you think your baby may have a group B strep infection.
Preventing and treating strep B infections in babies
It's possible to reduce the chances of a baby becoming infected with strep B by identifying cases where there is a risk of the bacteria being passed from a mother to their child and giving the mother antibiotics directly into a vein (intravenously) during labour.
Known risk factors that may mean you need intravenous antibiotics during labour include:
- you have previously given birth to a baby with a strep B infection
- strep B is found in your urine during tests carried out for other purposes
- strep B is found during vaginal and rectal swabs carried out for other purposes
- you have a fever during labour
- you go into labour prematurely (before 37 weeks of pregnancy)
If your baby develops symptoms of a strep B infection after they're born, they will have tests to confirm the diagnosis and will be given intravenous antibiotics as soon as possible.
Most babies who become infected can be treated successfully and will make a full recovery, although there is chance they could die as a result of complications such as meningitis, and some babies who survive are left with permanent problems, such as hearing loss, vision loss, and problems with memory and concentration.