The Ultimate Guide to Streptococcus agalactiae (Group B Strep)
Carried by 1 in 4 women without symptoms. Causes recurrent UTIs and poses serious risks during pregnancy – including life-threatening infections in newborns.
Streptococcus agalactiae, commonly known as Group B Streptococcus (GBS), is a bacterium that normally lives in the vagina, rectum, and lower gut of healthy adults. In most people, it causes no harm at all. However, it can cause urinary tract infections – particularly in pregnant women, older adults, and people with diabetes – and is the leading cause of life-threatening infections in newborns (Seale et al., 2017).
GBS-related UTIs are frequently misdiagnosed because standard urine dipstick tests do not specifically identify this organism. Without PCR testing, GBS can be missed entirely or treated with the wrong antibiotic.
Why GBS Matters for UTIs and Pregnancy
Critical for pregnant women. GBS in the urinary tract during pregnancy indicates heavy colonisation and increases the risk of preterm birth, premature rupture of membranes, and transmission to the baby during delivery. Neonatal GBS infection can cause sepsis (a life-threatening blood infection), pneumonia, and meningitis (infection of the brain lining) – with a mortality rate of 5 – 10% even with treatment (Seale et al., 2017).
Symptoms of a GBS UTI
Painful or stinging sensation when urinating, similar to typical bacterial UTIs.
Needing to urinate more often than usual, sometimes every 20 – 30 minutes.
Fever with flank pain (pain in the side of the lower back) may indicate the infection has spread to the kidneys.
In pregnancy, GBS in urine is often asymptomatic (no symptoms) – detected only through routine screening or when tested as part of a UTI investigation.
Who Is Most at Risk?
GBS in urine during pregnancy requires treatment and monitoring throughout the remainder of the pregnancy. It indicates heavy colonisation that could be transmitted to the baby during delivery.
GBS is an underdiagnosed cause of recurring UTIs. Standard E. coli-targeted antibiotics do not treat GBS effectively, so the infection keeps coming back.
Age-related decline in immune function increases susceptibility to GBS UTIs, particularly in care facilities.
Elevated blood sugar supports bacterial growth and weakens the immune response, making GBS UTIs more likely and harder to clear.
This includes people living with HIV, those on cancer treatment, and organ transplant recipients whose immune-suppressing medication makes them vulnerable.
Early detection matters. If GBS is found in a urine sample during pregnancy, it indicates heavy colonisation. This triggers a protocol of antibiotics during labour (given through a drip) to prevent transmission to the baby. PCR testing identifies GBS with higher sensitivity than standard cultures. For women planning pregnancy, knowing your GBS status beforehand is valuable.
Group B Strep in South Africa
Private Healthcare
Private obstetricians in South Africa increasingly offer GBS screening at 35 – 37 weeks of pregnancy, but it is not yet universal even in private practice. Many women are unaware that GBS screening is something they can – and should – request. For women experiencing recurrent UTIs, GBS is frequently overlooked as a cause because it is primarily associated with pregnancy in the public consciousness. Women using private fertility clinics should also be aware that GBS colonisation can affect conception and early pregnancy outcomes.
Public Healthcare
South Africa's public maternity services do not routinely screen for GBS. The risk-based approach (screening only if risk factors are present) means many colonised women are never identified. In communities with high HIV prevalence, the interaction between a weakened immune system and GBS colonisation increases the risk of both maternal UTIs and neonatal transmission. Limited access to laboratory services in rural clinics means GBS is often diagnosed only after a newborn becomes symptomatic.
Travellers and Foreign Nationals
Pregnant travellers or expatriates delivering in South Africa should be aware that GBS screening protocols differ from those in the UK, US, or Australia, where universal screening is standard. If your home country's protocol requires GBS screening and you are receiving antenatal care in SA, you may need to request it specifically. Epicentre offers walk-in testing without a referral – a GBS result can be obtained independently and shared with your obstetrician.
Epicentre's UTI PCR Panel
UTI Package – 11-Target PCR Screen
Results in 5 – 7 working days · No doctor's referral needed · Walk-in or home kit available
Stop Guessing. Get Tested.
11-target UTI PCR panel. Walk in to any Epicentre branch – no doctor's referral needed – or order a home collection kit.
Frequently Asked Questions
What Is Group B Strep (GBS)?
How Is C. lusitaniae Diagnosed?
Why Do My UTIs Keep Coming Back?
Do I Need a Doctor's Referral?
References
- CDC (2024). Group B Strep (GBS): fast facts. Centers for Disease Control and Prevention.
- Seale, A.C. et al. (2017). Estimates of the burden of Group B streptococcal disease worldwide for pregnant women, stillbirths, and children. Clinical Infectious Diseases, 65(S2), S200 – S219.
