A urinary tract infection (UTI) is an infection from microbes. These are organisms that are too small to be seen without a microscope. Most UTIs are caused by bacteria, but some are caused by fungi and in rare cases by viruses. UTIs are among the most common infections in humans.A UTI can happen anywhere in your urinary tract. Your urinary tract is made up of your kidneys, ureters, bladder, and urethra. Most UTIs only involve the urethra and bladder, in the lower tract. However, UTIs can involve the ureters and kidneys, in the upper tract. Although upper tract UTIs are more rare than lower tract UTIs, they’re also usually more severe. Treatment of UTIs depends on the cause. Your doctor will be able to determine which organism is causing the infection from the test results used to confirm the diagnosis.In most cases, the cause is bacteria. UTIs caused by bacteria are treated with antibiotics.In some cases, viruses or fungi are the causes. Viral UTIs are treated with medications called antivirals. Often, the antiviral cidofovir is the choice to treat viral UTIs. Fungal UTIs are treated with medications called antifungals. The form of antibiotic used to treat a bacterial UTI usually depends on what part of the tract is involved. Lower tract UTIs can usually be treated with oral antibiotics. Upper tract UTIs require intravenous antibiotics. These antibiotics are put directly into your veins.Sometimes, bacteria develop resistance to antibiotics. Results from your urine culture can help your doctor select an antibiotic treatment that will work best against the type of bacteria that’s causing your infection.Treatments other than antibiotics for bacterial UTIs are being examined. At some point, UTI treatment without antibiotics may be an option for bacterial UTIs by using cell chemistry to change the interaction between the body and the bacteria.