Bladder Infection – Diagnosis, Symptoms, and Treatment

Doctor Nathan LeDeaux, MD

Medically reviewed by Dr. Nathan LeDeaux, MD

Medical Professional

Updated - December 14, 2020

Nathan LeDeaux is an emergency medicine physician at the University of Wisconsin and got his M.D. from Northwestern University in Chicago Illinois.

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What is a Urinary Tract Infection?

Urinary tract infections are the presence of excessive amounts of bacteria within the urethra, bladder, or ureters that carry urine from the kidneys to the bladder. Symptoms generally begin when bacteria are able to grow in large numbers within the bladder. This is much more common in women as the urethra is shorter and bacteria can more easily reach the bladder. 

Patients whose urinary tract infection reaches the bladder will present with a bladder infection, known as cystitis. They typically develop suprapubic discomfort, burning on urination (dysuria), cloudy urine, abnormal smelling urine, and fever.  Some patients develop blood in the urine.  If the infection ascends up the urinary tract into the kidneys, individuals may develop back pain, nausea, and vomiting.  Mild cases of kidney infection (pyelonephritis) can be managed as an outpatient but severe cases often require hospitalization for intravenous fluids and antibiotics.

What Causes a Urinary Tract Infection?

Urinary tract infections are caused by bacterial infection of the urinary tract – kidneys, ureters, bladder, prostate (in men), and the urethra.  The most common organisms that cause urinary tract infections include Escherichia coli, Klebsiella, Proteus, and Group B streptococcus.  Most of these bacteria originate from the colorectal area and translocate to the urethra – this is more common in women due to their shorter urethra that is closer in proximity to the anus.  Women are usually encouraged to wipe backward after a bowel movement, avoiding forward motion toward the vagina and urethra.

Certain conditions increase the risk of developing urinary tract infections include:

  • Female gender
  • Pregnancy
  • Recent sexual intercourse
  • Advanced age
  • Urinary retention – due to medications, spinal cord injury, or an enlarged prostate in men
  • Prior urologic surgery
  • Foley catheter placement
  • Urinary stent placement
  • Kidney stones

When the bacteria in the urethra reach the bladder bacteria can flourish and rapidly replicate in any urine stored there – producing symptoms such as fever, suprapubic pain, urinary frequency, and dysuria. If the infection advances up the urinary tract into the kidneys it is called pyelonephritis.  This tends to be a more severe infection that causes back pain, fever, nausea, and vomiting.  Pyelonephritis can lead to acute kidney injury, sepsis, and shock.  These serious complications may ultimately lead to death if not caught early and treated with appropriate antimicrobial therapy.

How Common are Urinary Tract Infections?

Urinary tract infections are extremely common in the United States. The simplest form, infection of the urethra alone is the most common. It is impossible to estimate how many people experience this form of urinary tract infection as many resolve on their own and very few people seek treatment. 

Infections that make it to the bladder are more severe and generally require treatment with medication. Overall it is estimated that 11% of the U.S population will experience a urinary tract infection affecting the bladder in a given year. The two age groups most severely affected are women between 14 and 24 due to sexual activity and women over the age of 65 due to a decrease in the ability to perform personal hygiene and an increase in the amount of urine stored in the bladder. 

The most severe forms of urinary tract infections, those that affect the kidneys are rarer. Around 0.5% of the U.S. population will experience one of these more severe infections in a given year. 

Signs and Symptoms

Symptoms of urinary tract infection depend on the location of the infection. Urethritis is the infection of the urethra alone, it typically leads to the following symptoms: 

  • Dysuria - burning on urination
  • Urinary frequency 

  Cystitis is an infection of the bladder, in addition to the above symptoms cystitis leads to symptoms in the area of the bladder. Inflammation of the bladder walls leads to pain and infection of the stored urine leads to changes in the smell and appearance of the urine. 

    • Dysuria – burning on urination
    • Urinary frequency
    • Urinary incontinence
    • Suprapubic abdominal pain
    • Changes in the smell or appearance of urine
  • Bloody urine 

Pyelonephritis is the infection of the kidneys, this leads to pain in the upper back, where the kidneys are located. Due to the amount of blood that flows through the kidneys an infection here rapidly spreads bacteria through the body and results in severe symptoms:

    • Fever
    • Back pain
    • Nausea & vomiting
    • Fast heart rate
  • Low blood pressure
  • Dizziness or fainting upon standing 

Prostatitis is an infection of the prostate, a gland that is only found in males. Generally, its symptoms are similar to that of pyelonephritis but it has a few unique symptoms as well:

  • Lower back pain
  • Pain with bowel movements

Bladder infection (cystitis) often results in tenderness when the doctor presses in the area right above the pelvis (the suprapubic area).  Patients with pyelonephritis typically have pain when the doctor taps on their back near the kidneys – this is referred to as costovertebral angle tenderness.  Men with prostatitis – infection of the prostate gland – typically have pain on palpation of the prostate during a rectal examination.


The diagnosis of urinary tract infection is suggested based on the history of symptoms and a physical examination but is typically confirmed with laboratory studies.

A test known as a urine dipstick is generally ordered in all types of urinary tract infection. This is a quick in-office test used to check for the presence of blood, protein, and markers that suggest bacterial infection known as nitrites and leukocyte esterase.  If these markers come back positive you will generally be given antibiotics and more tests will be sent. 

The additional tests are known as a urinalysis and a urine culture, these allow the doctor to determine exactly what type of bacteria is causing your infection. These test results take up to 48 hours to come back. Based on these results your doctor may change your antibiotic prescription to one that is more likely to kill the specific bacteria in your urine. 


If more severe forms of urinary tract infection, your doctor may obtain blood tests such as a CMP (comprehensive metabolic panel) and CBC (complete blood cell count).  If you have signs of bacteria spreading into your bloodstream they will also likely order blood cultures, these are similar to the urine cultures discussed above.  Occasionally, they will obtain an ultrasound or CT scan of the abdomen to ensure that there are no pockets of walled-off infection in the kidneys, known as an abscess. Or kidney stones that could have become infected and will not be effectively treated by oral antibiotics alone. 

Urinary Tract Infection Medication and Treatment

Simple urinary tract infections in women can be treated with oral antibiotics for 3-7 days, the exact prescription used will vary based on where you live, certain areas of the country have higher levels of bacterial resistance to certain antibiotics used for UTI.  The most commonly prescribed antibiotics for urinary infections include:

Specific bacteria known as enterococcus usually require therapy with specific antibiotics such as ampicillin or vancomycin that have more side effects than the commonly used therapies. There has even been an emergence of vancomycin-resistant enterococcus (VRE), which requires treatment with Zyvox (linezolid), an even more specialized antibiotic. The urine culture performed at the time of your UTI diagnosis will tell your physician if the use of these medications is necessary. 

Extended-spectrum beta-lactamase (ESBL) organisms are a type of resistant bacteria that may require intravenous therapy with another specialized family of antibiotics known as carbapenems:

  • Primaxin (imipenem/cilastatin)
  • Merrem (meropenem)
  • Invanz (ertapenem)


  1. Gupta K, Hooton TM, Naber KG, et al. International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: A 2010 update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases. Clin Infect Dis 2011; 52:e103. -
  2. Czaja CA, Scholes D, Hooton TM, Stamm WE. Population-based epidemiologic analysis of acute pyelonephritis. Clin Infect Dis 2007; 45:273. -


Bladder Infection Medicine

The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.