Causes of UTIs

Urinary tract infections are not unfamiliar territory to many. With more than 150 million people developing one each year, these infections have become one of the most common types of health issues in the world. And, if you’re one of the millions who have had one, then you’ve probably wondered what causes UTIs. The answer is simple: the most common UTI causes are a result of invasive bacteria. 

There’s pretty much one major cause: bacteria

A urinary tract infection, or UTI, is a common infection that affects the kidneys, bladder, and urethra. Infections almost always start in the urethra, which is the urinary tract’s main point of entry. While most infections stay there, it’s possible for them to spread up into the bladder and kidneys. These types of infections all have a unique name, and you may hear your doctor reference any of these terms:

  • Urethritis (Urethra)
  • Cystitis (Bladder)
  • Pyelonephritis (Kidneys)

What bacteria causes UTIs?

While the human body does its best to avoid UTIs naturally by pushing out bacteria during urination, there’s always a chance that some microorganisms are left behind—especially one bacteria called Escherichia coli, which causes almost all urinary tract infections. 

Better known as E. coli, this bacteria is a common pathogen found in the human digestive tract. There, E. coli is very harmless and necessary, ensuring a healthy gut by aiding in food digestion and nutrient absorption. But when E. coli is accidentally introduced to other parts of the body, the bacteria can cause issues.

What causes UTIs in women?

Half of all women get urinary tract infections, compared to about 10% of men, so it’s especially important for women to know how they can protect themselves E. coli. The big reason that women get more UTIs than men is that women have shorter urethras, which means it’s much easier for bacteria to travel up into the urinary tract. Some things make it easier for E. coli to travel up the urinary tract too, like sex and wiping back to front (instead of front to back).

The urogenital system (the vagina plus the urinary tract) requires a delicate balance of good bacteria to keep the bad bacteria (like E. coli) in check. Whenever bad bacteria becomes over represented in the urogenital system, this can throw off the microbiome, making it easier for UTIs or other infections like bacterial vaginosis (BV) to develop.

Secondary causes: fungi & viruses

Although not as common, certain fungi, like yeast, and viruses can infect the urinary tract system. Vaginal yeast infections—which together with bacterial vaginosis affect 75 percent of women worldwide—can also increase the risk of UTIs by making the urinary tract more vulnerable to E. coli..

The most typical yeast is called Candida, which lives naturally in the vagina, but when present in the urinary indicates an infection. Candida primarily affects the bladder and kidneys and is usually caused by urinary catheters or other medical conditions, like yeast infections. 

Common viruses can also throw off the microbiome, making it easier for issues like UTIs to develop. Most of the time, these are from viral sexually transmitted diseases (STDs) and infections (STIs), but can also be caused by exposure to certain environments. Common viruses include:

  • Human Papillomavirus Infection (HPV) 
  • Human Immunodeficiency Virus (HIV)
  • Infectious Mononucleosis (“Mono”)
  • Chlamydia trachomatis
  • Schistosomiasis (Parasitic flatworms found in freshwater) 

Even if you are careful about staying healthy, several types of bacteria, fungus, and viruses can make their way into your body seemingly unannounced. And although you can’t stop a UTI once it’s taken action, you can lessen your chances of developing one by understanding the most common risk factors.

Risk factors

UTIs can often depend on your lifestyle, habits, anatomy and genetics. Other times, they may be the result of surgery or medication. If you’re taking antibiotics and have wondered: “Can antibiotics cause UTIs?” then it’s essential to talk with your doctor about the side effects of your prescribed medication.

Additionally, there are many other risk factors that are associated with common UTI causes, including: 

  • Sex, especially frequently and/or with new partners
  • Holding your bladder for too long
  • Spandex, or other clothing that doesn’t allow for breathability 
  • Certain sports like riding bicycles or swimming 
  • Simple being a woman, since women have shorter urethras
  • Wiping back-to-front instead of front-to-back
  • Surgeries and catheters
  • Certain medications and antibiotics
  • Diabetes
  • Back injuries
  • Kidney stones
  • Birth control (especially the diaphragm or spermicide)
  • Testosterone
  • Genetic predisposition, which could cause a weakened immune system
  • Diets that are high in sugar or alcohol

If you suspect that you have a UTI, it could be a result of many different things.

What can I do for my UTI?

Now that you know what can cause a UTI, it’s time to get the right treatment. 

Depending on the UTI causes and type of infection, your doctor may recommend antibiotics or other treatments so that you can avoid discomfort in the next coming days. Although some people are prone to recurring infections, your doctor may also recommend some lifestyle changes or health supplements to get your body back on the right track. Learn more about how you can treat your UTI. 


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