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What is the main cause of a UTI?

What is the main cause of a UTI?

Navin Khosla NowPatientGreen tick
Created on 1 Jul 2024
Updated on 16 Jul 2024

Urinary tract infections (UTIs) are a common health issue, affecting millions of people worldwide each year. These infections can occur in any part of the urinary system, including the bladder, urethra, ureters, and kidneys. While UTIs can be treated with antibiotics, it’s important to understand the causes behind these infections to better prevent and manage them.

The urinary tract: A closer look

The urinary tract is responsible for the production, storage, and elimination of urine from the body. It is made up of the kidneys, ureters, bladder, and urethra. The kidneys filter waste and excess water from the blood, forming urine, which travels through the ureters to the bladder. The bladder stores the urine until it’s time for you to urinate, and the urethra is the tube that carries the urine out of the body.

Cause of UTIs: Bacteria

The major cause of urinary tract infections are bacteria, with Escherichia coli (E. coli) being the primary culprit. E. coli is commonly found in the gastrointestinal (GI) tract, and it can easily spread from the anus to the urethra, particularly in women who have a shorter urethra than men.

How bacteria enter the urinary tract

Bacteria can enter the urinary tract through various means, including:

  • Sexual activity: Bacteria can be introduced into the urethra and then travel to the bladder, causing an infection
  • Poor hygiene: Wiping from the back to front after bowel movements, can allow bacteria from the anus to enter the urethra
  • Catheters and medical procedures: Catheters or other medical instruments that enter the urinary tract can introduce bacteria, increasing the risk of infection
  • Weakened immune system: Individuals with diabetes or undergoing cancer treatment, are more susceptible to bacterial infections

The role of E. coli bacteria

E. coli causes over 90% of bladder infections. This bacteria typically lives in the lower intestines, but can easily move into the urethra, especially in women due to their shorter urethral length and proximity to the anus.

Symptoms of a UTI

Symptoms of UTIs can vary depending on the location and severity of the infection. Common symptoms include:

  • Frequent or urgent need to urinate
  • Burning or pain when peeing (cystitis)
  • Cloudy, foul-smelling, or bloody urine
  • Pelvic or lower abdominal pain
  • Back pain or discomfort
  • Fever, chills, and tiredness

In older adults or people with a weakened immune system, symptoms of a urinary tract infection may be less obvious, such as changes in behaviour, confusion, or incontinence.

Risk factors for developing UTIs

Certain factors can put individuals at a higher risk of developing a urinary tract infection, including:

  • Anatomy: Women have a shorter urethra than men, making it easier for bacteria to reach the bladder
  • Sexual activity: Especially with a new partner, can increase the risk of UTIs
  • Birth control: Certain birth control methods, such as diaphragms and spermicides, can contribute to bacterial growth and UTI development
  • menopause: A decline in estrogen levels after menopause can lead to changes in the urinary tract that increase the risk of UTIs
  • Urinary tract abnormalities: Kidney stones or an enlarged prostate, can increase the risk of UTIs
  • Weakened immune system: Individuals with diabetes or undergoing cancer treatment, are more susceptible to UTIs

Preventing urinary tract infections

It is essential to take steps to prevent UTIs in the first place. Effective prevention strategies include:

  • Proper hygiene: Wiping from front to back after using the bathroom and keeping the genital area clean and dry can help reduce the risk of bacterial infections. Wearing cotton underwear is also helpful as cotton allows more airflow than synthetic materials
  • Increased fluid intake: Drink plenty of water to flush out bacteria from the urinary tract and to prevent infections
  • Urinating after sexual activity: This can help eliminate any bacteria that may have been introduced
  • Avoiding irritants: Avoid using scented feminine products, douches, and certain birth control methods to help maintain a healthy urinary tract environment
  • Cranberry products: Cranberry juice or supplements may help prevent UTIs, although the evidence is not conclusive

Diagnosing and treating UTIs

Seek medical attention if you suspect you have a urinary tract infection. Healthcare providers can diagnose UTIs through various tests, including:

  • Urinalysis: This test examines a urine sample for signs of infection, such as white blood cells or bacteria
  • Urine culture: A urine culture can identify the specific bacteria and help determine the most effective antibiotic treatment

In most cases, UTIs are treated with a course of antibiotics prescribed by a healthcare provider. Follow the instructions provided carefully and complete the full course, even if your symptoms improve, to ensure the infection is fully cleared.

Recurrent UTIs

Some individuals may experience recurrent or chronic UTIs, where the infections keep returning or never fully resolve. In these cases, healthcare providers may recommend:

  • Long-term antibiotic therapy: Low-dose antibiotics taken for an extended period of time to help prevent recurring UTIs
  • Vaginal estrogen therapy: For postmenopausal women, topical estrogen creams can help restore the vaginal environment and reduce the risk of UTIs
  • Referral to a specialist: If the UTIs persist or are accompanied by other complications, a referral to urology may be necessary for further evaluation and treatment


Urinary tract infections are a common and often frustrating health issue, but by understanding the primary cause, individuals take the necessary steps to prevent and manage these infections. By maintaining good hygiene, staying hydrated, and seeking prompt medical attention, individuals can reduce their risk of developing UTIs and improve their overall urinary tract health.


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NowPatient has taken all reasonable steps to ensure that all material is factually accurate, complete, and current. However, the knowledge and experience of a qualified healthcare professional should always be sought after instead of using the information on this page. Before taking any drug, you should always speak to your doctor or another qualified healthcare provider.

The information provided here about medications is subject to change and is not meant to include all uses, precautions, warnings, directions, drug interactions, allergic reactions, or negative effects. The absence of warnings or other information for a particular medication does not imply that the medication or medication combination is appropriate for all patients or for all possible purposes.

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