Streptococcal infections is a general term which is used to refer to any sort of infection caused by a type of bacteria known as streptococcal.
Infections that are caused by the streptococcal bacteria can range from being mild, such as a sore throat, to life threatening, such as necrotizing fasciitis (the so called ‘flesh-eating’ bacteria).
Types of streptococcal bacteria
There are more than 20 different types of streptococcal bacteria. The two most common types in humans are:
- group A streptococcus (GAS), and
- group B streptococcus (GBS).
Group A streptococcus
Group A streptococcus (GAS) is commonly found on the skin and inside the throat, and in many people does not cause any symptoms. The most common type of infections caused by GAS are a sore throat (sometimes called strep throat) and minor skin infections such as impetigo (a skin condition that children often have).
Invasive streptococcal infection
GAS only presents a more serious problem if the bacteria penetrate further into the body, such as into the blood, or into a deeper layer of skin. This type of infection is known as an invasive streptococcal infection.
People who are most at risk of an invasive streptococcal infection include:
- the very young,
- people aged 75 years of age or over, and
- people with weakened immune systems.
Group B streptococcus
Group B streptococcus (GBS) is commonly found in the digestive system and the female reproductive system. Most children rapidly develop immunity to GBS, but the bacteria can be a serious threat to newborn babies who get infected.
Infections in newborn babies can lead to potentially serious conditions, such as meningitis (inflammation of the meninges, the membranes that surround the brain) or pneumonia (inflammation of the lungs).
How common are streptococcal infections?
Non-invasive GAS infections are common. It is hard to get a precise figure because most infections are mild, and many people do not report their symptoms to their GP. One estimate is that one in every four sore throats is caused by a GAS infection.
Invasive GAS infections are rare. In England it is estimated that each year three out of every 100,000 people will have an invasive infection
GBS infections in newborns are uncommon. It is estimated that one out of every 2000 babies born in England will develop a GAB infection.
Outlook
The outlook for non-invasive GAS infections is good. Most cases of throat infection will pass without the need for treatment. Skin infections may require antibiotics but usually respond well.
The outlook for invasive GAS infections is poor. An estimated 15-25% of people who contract an invasive GAS infection will die.
The outlook for GBS infections in newborns is also poor. Although the mortality rates have improved significantly in recent years, one in every 10 babies will die from a GBS infection.
