10 Causes of UTIs: Why Your UTI Keeps Coming Back
Most UTIs are blamed on E. coli. But E. coli is only one of at least 10 organisms that can infect your urinary tract – and most of them travel through the vaginal microbiome to get there.
If your UTI keeps coming back, the problem may not be the treatment – it may be the diagnosis. Standard urine dipsticks detect bacterial markers only. They cannot identify which bacterial species is causing the infection, and they miss fungal UTIs completely. This means you could be treated for the wrong organism, or for an organism that is resistant to the treatment prescribed.
PCR testing changes this. Instead of detecting indirect markers, PCR identifies the DNA of the organism itself – bacteria AND fungi, with species-level accuracy, in a single test. Epicentre's UTI panel tests 11 organisms, covering the most common causes of both simple and recurrent UTIs.
How the Vaginal Microbiome Causes UTIs
The Vaginal-Urinary Pathway
Most UTIs do not start in the bladder. They begin with organisms that colonise the vaginal and perineal area first. When the vaginal microbiome is healthy – dominated by protective Lactobacillus species – these organisms are kept in check. When Lactobacillus declines, the barrier weakens and pathogens can ascend.
This is why vaginal health and UTI health are inseparable. Treating a UTI without understanding the vaginal microbiome is like mopping the floor while the tap is still running. If the vaginal barrier is disrupted, new infections will keep arriving.
The 10 Most Common Causes of UTIs
Escherichia coli (E. coli)
Responsible for 70 – 80% of all UTIs. E. coli normally lives in the gut but migrates to the perineal and vaginal area, then ascends into the urethra. Uropathogenic strains (UPEC) have specialised adhesion structures that allow them to cling to the bladder wall and resist being flushed out by urination.
Enterococcus faecalis
The second most common bacterial cause of UTIs. Lives in the gut and reaches the urinary tract via the same perineal-vaginal pathway as E. coli. Particularly common in catheter-associated UTIs and in patients who have recently taken antibiotics, because it thrives when competing bacteria are eliminated.
Candida albicans
The most common cause of fungal UTIs. Produces identical symptoms to bacterial UTIs – burning, urgency, frequency – but is invisible to standard urine dipsticks. This is the single most common reason for a "negative" UTI test in someone with clear UTI symptoms. Often follows antibiotic use, which kills bacteria but allows yeast to overgrow.
Low Lactobacillus (Disrupted Vaginal Flora)
Lactobacillus is the guardian of the vaginal microbiome. It produces lactic acid, maintaining a low pH that prevents pathogens from colonising. When Lactobacillus declines – from antibiotics, hormonal changes, douching, or stress – the vaginal pH rises and UTI-causing organisms gain easy access to the urethra. This is not a UTI cause itself, but the gateway condition that enables most recurrent UTIs.
Gardnerella vaginalis (Bacterial Vaginosis)
The hallmark organism of BV. When Gardnerella overgrows, it forms biofilms on the vaginal wall that displace Lactobacillus and create an alkaline environment. Women with BV have a significantly higher risk of UTIs because the disrupted vaginal microbiome provides a corridor for uropathogens. BV and recurrent UTIs frequently co-exist.
Staphylococcus aureus
Can colonise the vaginal tract and ascend to the urinary tract. Less common than E. coli but clinically important because it can cause severe kidney infections. Also associated with catheter-related UTIs in hospital settings.
Group B Streptococcus (Streptococcus agalactiae)
Colonises the vaginal tract in 10 – 30% of healthy women. Usually harmless, but can ascend to cause UTIs – particularly during pregnancy, when hormonal changes alter the vaginal microbiome. Also a critical concern for newborn health during delivery.
Candida krusei
100% resistant to standard first-line antifungal treatment. Every single isolate, every time. Most commonly found in cancer patients who have received antifungal prophylaxis during chemotherapy – the very treatment designed to prevent fungal infections selects for this species. If your fungal UTI does not respond to standard treatment, C. krusei should be suspected.
Candida glabrata
Develops resistance to standard antifungal therapy over time – unlike C. krusei, which is born resistant, C. glabrata acquires resistance with repeated treatment exposure. Increasingly common in women over 50, diabetic patients, and those with recurrent vaginal candidiasis. Often co-exists with C. albicans.
Klebsiella pneumoniae
The third most common bacterial cause of UTIs after E. coli and Enterococcus. Particularly prevalent in hospital-acquired UTIs and in diabetic patients. Produces a thick capsule that makes it difficult for the immune system to clear, contributing to persistent and recurrent infections.
Your UTI might have more than one cause. PCR testing frequently reveals multiple organisms in a single sample – for example, E. coli and Candida albicans together, or Enterococcus faecalis alongside low Lactobacillus. Standard dipsticks can only detect one thing: the presence of bacteria. PCR identifies every organism present, at species level.
Why Standard UTI Tests Miss So Much
A standard urine dipstick looks for two bacterial markers: nitrites (produced when bacteria convert nitrates in urine) and leukocyte esterase (a white blood cell enzyme indicating immune response). This approach has three critical blind spots:
- Yeast is invisible. Candida species do not produce nitrites or trigger the same immune markers. A fungal UTI will return a negative dipstick despite real, persistent symptoms
- No species identification. Even when bacteria are detected, the dipstick cannot tell you which species. Treatment is prescribed empirically – essentially a guess based on what is most likely, not what is actually present
- Resistant species are missed. The dipstick might confirm "bacteria present" but cannot distinguish between a susceptible E. coli and a resistant organism that requires a different treatment approach
PCR testing eliminates all three blind spots. It identifies the specific organism by its DNA, detects both bacteria and fungi in a single test, and distinguishes between resistant species (like C. krusei) and susceptible ones.
Could Your Vaginal Microbiome Be Contributing to Your UTIs?
UTIs in South Africa
Urban and Suburban Women
Recurrent UTIs are frequently treated with repeated courses of the same empirical therapy without species identification. Each course of antibiotics disrupts the vaginal Lactobacillus further, increasing the risk of the next UTI – creating a cycle that can only be broken by identifying what is actually causing the infection.
Lower-Income Communities
Limited access to advanced diagnostics means UTIs in public healthcare are almost always treated empirically. With 67.7% UTI prevalence in some SA communities, the scale of untargeted treatment is significant. Walking into an Epicentre branch requires no doctor's referral and no appointment.
Travellers and Foreign Nationals
Different antibiotic resistance patterns across regions mean a UTI acquired in South Africa may not respond to the treatment protocol used in Europe or North America. PCR identification ensures your healthcare provider at home knows exactly which organism to target.
Which Test Is Right for You?
UTI Package – 11-Target PCR Screen
BV Microbiome Test – 25-Organism Panel
How the Home Test Kit Works
If you cannot visit an Epicentre branch, order a home collection kit and test from anywhere in South Africa.
Order
Order from the Epicentre shop. Discreet, unmarked packaging.
Collect
Follow clear instructions to collect your urine or swab sample at home.
Return
Post it back using the prepaid return label included in the kit.
Results
Colour-coded results digitally within 5 – 7 working days.
Frequently Asked Questions
Why Does My UTI Keep Coming Back?
Can Vaginal Bacteria Cause a UTI?
Can a Yeast Infection Cause a UTI?
Why Does My UTI Test Come Back Negative?
What Is the Connection Between BV and UTIs?
Can Men Get UTIs from These Causes?
How Does the Home Test Kit Work?
Do I Need a Doctor's Referral?
References
- Mahlangu, P. et al. (2020). Urinary tract infections in South African women: prevalence and risk factors. Southern African Journal of Infectious Diseases, 35(1), a215.
- Flores-Mireles, A.L. et al. (2015). Urinary tract infections: epidemiology, mechanisms of infection, and treatment options. Nature Reviews Microbiology, 13(5), 269 – 284.
- Stapleton, A.E. (2016). The vaginal microbiota and urinary tract infection. Microbiology Spectrum, 4(6).
