Most urinary tract infections (UTIs) are caused by the E. coli bacteria, which are treated with antibiotics. But some strains may be resistant to common antibiotic types.

A UTI occurs when germs (bacteria) invade the urinary tract. It’s incredibly common, and while males assigned at birth (MAABs) aren’t immune, females assigned at birth (FAABs) are 30 times more likely to develop a UTI, mostly because of the structure of their urinary tract.

UTIs can have different causes, one of which is a bacteria called Escherichia coli (E. coli). About 80% of UTI cases are caused by this microorganism.

For the most part, E. coli lives harmlessly in your gut. But it can cause problems if it enters your urinary system, usually from stool that migrates into the urethra.

Because E. coli is a bacteria, treatment usually involves antibiotics. However, antibiotic resistance can sometimes make treatment difficult.

To determine if there are bacteria in your urine, you’ll need to undergo a urinalysis. If your test comes back positive for E-coli, a doctor will likely prescribe one of several antibiotics that work to kill this bacteria.

The two antibiotics most commonly prescribed for an E. Coli-caused UTI are trimethoprim/sulfamethoxazole (Bactrim, Sulfatrim) and nitrofurantoin (Macrobid).

Other oral antibiotics that may be prescribed for a UTI caused by E-coli include:

Another antibiotic, pivmecillinam (Selexid, Pivya), was recently approved by the Food and Drug Administration (FDA) and may become available for prescribing in the near future.

If you have recurrent infections, or if your infection is severe, you may need to take antibiotics for a few months or may need injected antibiotics such as plazomicin (Zemdri).

Other than antibiotics, researchers are currently investigating the supplement d-mannose as a possible remedy for UTI.

A 2022 study suggests that consuming d-mannose may help prevent UTIs because this substance passes through the kidneys and attaches to E. coli bacteria, helping prevent infection. That said, more study with a greater number of human subjects is necessary to confirm this.

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A urinalysis only tells you that you have a bacterial infection, but to find out specifically which strain of bacteria is the cause, a urine culture is required.

This is important because bacteria are becoming increasingly resistant to antibiotics. Resistance occurs as bacteria naturally change to break down or avoid the antibiotics typically used to fight them.

The more exposure a bacterium gets to an antibiotic, the more likely it is to alter itself to survive. Overuse and misuse of antibiotics make the problem worse.

For this reason, a urine culture can help your doctor decide the best antibiotic or combination of antibiotics to fight your infection.

Other bacteria that may cause UTIs and may require a different combination of drugs include:

  • Klebsiella pneumoniae
  • Pseudomonas aeruginosa
  • Staphylococcus saprophyticus
  • Enterococcus faecalis (group D streptococci)
  • Streptococcus agalactiae (group B streptococci)

UTIs generally can cause a range of symptoms, including:

  • an urgent, frequent need to pee, often with little urine output
  • bladder fullness
  • burning urination
  • pelvic pain
  • foul-smelling, cloudy urine
  • urine that’s brownish, pink, or tinged with blood

For the most part, E-coli bacteria lead to minor UTIs. But in some cases, infections can spread all the way up to the kidneys. This can be particularly serious. Symptoms include:

  • fever
  • pain in the upper back and side, where the kidneys are located
  • nausea and vomiting

Even a healthy urinary tract can host a variety of bacteria, but this doesn’t usually include E. coli.

E. coli often gains entry into the urinary tract via stool. FAABs are particularly at risk for UTIs because their urethra sits close to the anus, where E. coli is present.

It’s also shorter than that of MAABs, giving the bacteria easier access to the bladder, where the majority of UTIs occur, and the rest of the urinary tract.

Some factors that may raise the chance of getting an E-coli UTI include:

  • Sex: The mechanical action of sex can move E. coli-infected stool from the anus into the urethra and up the urinary tract.
  • Birth control: Contraceptives that use spermicides, including diaphragms and spermicidal condoms, can kill the healthy bacteria in your body that protect you from bacteria like E. coli. This bacterial imbalance can make you more susceptible to a UTI.
  • Pregnancy: Hormonal changes during pregnancy can affect the growth of certain bacteria. Some experts also think that the weight of a growing fetus can shift your bladder, making it easier for E. coli to gain access.

That said, there are some things you can do to reduce your chance of contracting it, including:

  • Wiping front to back after using the bathroom: Wiping back to front can carry E. coli from the anus to the urethra.
  • Washing your genital area: Genital hygiene is important, particularly after sexual intercourse and especially after anal sex.
  • Using a condom: Condom use can help lower the chance of coming in contact with the bacteria, especially during anal sex. Remember to change your condom between vaginal and anal sex.
  • Staying hydrated: Water can help clean out your urinary tract. Plus, there’s some evidence that cranberry juice, in particular, may be helpful in preventing UTIs.

UTIs are some of the most common infections doctors see. Most are caused by E. coli and are successfully treated with a round of antibiotics. If you have symptoms of a UTI, see a doctor.

Most UTIs are uncomplicated and don’t cause any lasting harm to your urinary tract. But UTIs that aren’t treated can progress to the kidneys, where permanent damage can occur.