The streptococcus or 'strep' bacterium causes streptococcal infections. These can affect anyone, from babies to older adults. These can affect anyone, from babies to older adults. Streptococcal infections may require antibiotic treatment and can range from mild to life-threatening.
Symptoms depend on the kind of infection and the part of the body affected.
Streptococcus infections may be more likely in people less able to fight off infections, such as people with weakened immune systems.
Streptococci infections are divided into groups:
Group A streptococcus
Group A streptococcus bacteria, also called GAS, tend to affect the throat, skin, anus and genital tract.
The bacteria spreads from close contact with an infected person through droplets in the air, and through contact with the skin, contaminated surfaces, objects and food.
This causes conditions including:
- Cellulitis, an infection of the deeper layers of skin causing infected areas to look red and swollen and to feel painful and hot.
- Ear infections.
- Erysipelas, a form of cellulitis affecting the upper skin layers.
- Impetigo, a highly contagious bacterial skin infection causing blisters and sores.
- Necrotising fasciitis, affecting a layer of connective tissue, known as the superficial fascia that lies beneath the skin and between muscles and organs in the body. The infection can spread aggressively, causing tissue death.
- Pneumonia, inflammation or swelling in the lungs in which the air sacs fill with pus and other fluids.
- Sinusitis, affecting the sinuses behind the nose.
- Scarlet fever, a rare bacterial illness causing a pink-red rash that feels like sandpaper.
- Sore throat or pharyngitis.
- Tonsillitis, affecting the tonsils. Bacterial tonsillitis is sometimes called strep throat.
Group B streptococcal infections
Group B streptococcus, or GBS, is part of the normal bacterial flora in the gut and genital tract.
Many pregnant women carry GBS in their gut or vagina. Most of these women go on to have healthy pregnancies and healthy babies.
However, the NHS says there is a small risk of the infection causing life-threatening complications for a newborn baby.
If a baby gets a GBS infection within a week of being born, this is called early-onset GBS infection. Around 340 babies a year in the UK develop this. There is currently no routine screening for GBS in pregnancy by the NHS - but the infection may be found during other testing. If a baby is thought to be at a high risk of GBS, antibiotics may be given during labour as a precaution.
Symptoms are usually seen in babies within 12 hours of birth - and include:
- Not feeding well
- Abnormal temperature
- Abnormal heart rate
- Abnormal breathing
The risks of GBS complications to a baby include:
- Septicaemia (blood poisoning)
- Pneumonia (lung infection)
- Meningitis (brain lining infection)
GBS risk to a baby is higher with:
- Early delivery, before 37 weeks of pregnancy
- Previous birth with a baby having GBS
- Birth longer than 18 hours after waters breaking
- Experiencing a high temperature in labour
If GBS develops more than a week after birth, this is not likely to be related to pregnancy.
GBS is not passed on through breastfeeding.
Group C & G streptococcal infections
These bacteria often cause infections of the throat, skin and soft tissue in the body. They spread from an infected person by sneezes, coughs or contact with an open wound.
These infections include:
- Bacteraemia, bacteria in the blood
- Bone infections
- Endocarditis, inflammation of the lining of the heart
- Joint infections
- Toxic shock.