Introduction – Urinary tract infection
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 rarer than lower tract UTIs, they’re also usually more severe.
Types of UTIs
An infection can happen in different parts of your urinary tract. Each type has a different name, based on where it is.
Cystitis (bladder): You might feel like you need to pee a lot, or it might hurt when you pee. You might also have lower belly pain and cloudy or bloody urine.
Pyelonephritis (kidneys): This can cause fever, chills, nausea, vomiting, and pain in your upper back or side.
Urethritis (urethra): This can cause a discharge and burning when you pee.
Pathophysiology of urinary tract infection
Uropathogenic bacteria, derived from a subset of fecal flora, have traits that enable adherence, growth, and resistance of host defenses. These traits facilitate colonization and infection of the urinary tract.
Adhesins are bacterial surface structures that enable attachment to host membranes. In E coli infection, these include both pili (ie, fimbriae) and outer-membrane proteins (eg, Dr hemagglutinin). P fimbriae, which attach to globoseries-type glycolipids found in the colon and urinary epithelium, are associated with pyelonephritis and cystitis and are found in many E coli strains that cause urosepsis.
Type 1 fimbriae bind to mannose-containing structures found in many different cell types, including Tamm-Horsfall protein (the major protein found in human urine). Whether this facilitates or inhibits uroepithelial colonization is the subject of some debate.
Other factors that may be important for E coli virulence in the urinary tract include capsular polysaccharides, hemolysins, cytotoxic necrotizing factor (CNF) protein, and aerobactins. Several Kauffman serogroups of E coli that contain these virulence factors may be more likely to cause UTIs, including O1, O2, O4, O6, O16, and O18.
Another example of bacterial virulence is the swarming capability of Proteus mirabilis. Swarming involves the expression of specific genes when these bacteria are exposed to surfaces such as catheters. This results in the coordinated movement of large numbers of bacteria, enabling P mirabilis to move across solid surfaces. This likely explains the association of P mirabilis UTIs with instrumentation of the urinary tract.
Causes of urinary tract infection
Large numbers of bacteria live in the area around the vagina and rectum, and also on your skin. Bacteria may get into the urine from the urethra and travel into the bladder. They may even travel up to the kidney. But no matter how far they go, bacteria in the urinary tract can cause problems.
Just as some people are more prone to colds, some people are more prone to UTIs. Women are more likely to get a UTI than men because women have shorter urethras than men, so bacteria have a shorter distance to travel to reach the bladder.
Some factors that can add to your chances of getting a UTI are:
Women who have gone through menopause have a change in the lining of the vagina and lose the protection that estrogen provides, which lowers the chance of getting a UTI. Some women are genetically predisposed to UTIs and have urinary tracts that make it easier for bacteria to cling to them. Sexual intercourse can also affect how often you get UTIs.
Women who use diaphragms have also been found to have a higher risk of UTIs when compared to those who use other forms of birth control. Using condoms with spermicidal foam is also known to be linked to a greater risk of getting UTIs in women.
You are more likely to get a UTI if your urinary tract has an abnormality or has recently had a device (such as a tube to drain fluid from the body) placed in it. If you are not able to urinate normally because of some type of blockage, you will also have a higher chance of a UTI.
Anatomical abnormalities in the urinary tract may also lead to UTIs. These abnormalities are often found in children at an early age but can still be found in adults. There may be structural abnormalities, such as outpouchings called diverticula, that harbor bacteria in the bladder or urethra or even blockages, such as an enlarged bladder, that keep the body from draining all the urine from the bladder.
Issues such as diabetes (high blood sugar) also put people at higher risk for UTIs because the body is not able to fight off germs as well.
Risk factors of urinary tract infection
Some people are at higher risk of getting a UTI. UTIs are more common in women and girls because their urethras are shorter and closer to the rectum, which makes it easier for bacteria to enter the urinary tract.
Other factors that can increase the risk of UTIs:
- A previous UTI
- Sexual activity, and especially a new sexual partner
- Changes in the bacteria that live inside the vagina (vaginal flora), for example, caused by menopause or use of spermicides
- Age (older adults and young children are more likely to get UTIs)
- Structural problems in the urinary tract, such as prostate enlargement.
- Poor hygiene, particularly in children who are potty-training
What are urinary tract infection symptoms and signs?
Lower urinary tract infection (infections of the bladder or urethra)
- Bladder (cystitis, or bladder infection): The lining of the urethra and bladder becomes inflamed and irritated.
- Dysuria: pain or burning during urination
- Frequency: more frequent urination (or waking up at night to urinate, sometimes referred to as nocturia); often with only a small amount of urine
- Urinary urgency: the sensation of having to urinate urgently
- Cloudy, bad-smelling, or bloody urine
- Lower abdominal pain or pelvic pressure or pain
- Mild fever (less than 101 F), chills, and “just not feeling well” (malaise)
- Urethra (urethritis): Burning with urination
Upper urinary tract infection (pyelonephritis, or kidney infection)
Symptoms develop rapidly and may or may not include the symptoms of a lower urinary tract infection.
- Fairly high fever (higher than 101 F)
- Shaking chills
- Flank pain: pain in the back or side, usually on only one side at about waist level
In newborns, infants, children, and elderly people, the classic symptoms of a urinary tract infection may not be present. Other symptoms may indicate a urinary tract infection.
- Newborns: fever or hypothermia (low temperature), poor feeding, jaundice
- Infants: vomiting, diarrhea, fever, poor feeding, not thriving
- Children: irritability, eating poorly, unexplained fever that doesn’t go away, loss of bowel control, loose bowels, change in urination pattern
- Elderly people: fever or hypothermia, poor appetite, lethargy, change in mental status
Pregnant women are at increased risk for a UTI. Typically, pregnant women do not have unusual or unique symptoms. If a woman is pregnant, her urine should be checked during prenatal visits because an unrecognized infection can cause pregnancy health complications.
Although most people have symptoms with a urinary tract infection, some do not.
The symptoms of urinary tract infection can resemble those of sexually transmitted diseases
Urinary tract infection – Complications
When treated promptly and properly, lower urinary tract infections rarely lead to complications. But left untreated, a urinary tract infection can have serious consequences.
Complications of a UTI may include:
- Recurrent infections, especially in women who experience two or more UTIs in a six-month period or four or more within a year.
- Permanent kidney damage from an acute or chronic kidney infection (pyelonephritis) due to an untreated UTI.
- Increased risk in pregnant women of delivering low birth weight or premature infants.
- Urethral narrowing (stricture) in men from recurrent urethritis, previously seen with gonococcal urethritis.
- Sepsis, a potentially life-threatening complication of an infection, especially if the infection works its way up to your urinary tract to your kidneys.
Diagnosis and Test
Female cystoscopy Open pop-up dialog boxCystoscopy exam for a man
Tests and procedures used to diagnose urinary tract infections include:
Analyzing a urine sample. Your doctor may ask for a urine sample for lab analysis to look for white blood cells, red blood cells, or bacteria. To avoid potential contamination of the sample, you may be instructed to first wipe your genital area with an antiseptic pad and to collect the urine midstream.
Growing urinary tract bacteria in a lab. Lab analysis of the urine is sometimes followed by a urine culture. This test tells your doctor what bacteria are causing your infection and which medications will be most effective.
Creating images of your urinary tract. If you are having frequent infections that your doctor thinks may be caused by an abnormality in your urinary tract, you may have an ultrasound, a computerized tomography (CT) scan, or magnetic resonance imaging (MRI). Your doctor may also use a contrast dye to highlight structures in your urinary tract.
Using a scope to see inside your bladder. If you have recurrent UTIs, your doctor may perform a cystoscopy, using a long, thin tube with a lens (cystoscope) to see inside your urethra and bladder. The cystoscope is inserted in your urethra and passed through to your bladder.
How a Urinary Tract Infection is treated?
Your health care provider must first decide if the infection is just in the bladder, or if it has spread to the kidneys and how severe it is.
Mild bladder and kidney infections
- Most of the time, you will need to take an antibiotic to prevent the infection from spreading to the kidneys.
- For a simple bladder infection, you will take antibiotics for 3 days (women) or 7 to 14 days (men).
- If you are pregnant or have diabetes, or have a mild kidney infection, you will most often take antibiotics for 7 to 14 days.
- Finish all of the antibiotics, even if you feel better. If you do not finish the whole dose of medicine, the infection may return and be harder to treat later.
- Always drink plenty of water when you have a bladder or kidney infection.
- Tell your provider if you might be pregnant before taking these drugs.
Recurrent bladder infections
Some women have repeated bladder infections. Your provider may suggest that you:
- Take a single dose of an antibiotic after sexual contact to prevent an infection.
- Have a 3-day course of antibiotics at home to use if you develop an infection.
- Take a single, daily dose of an antibiotic to prevent infections.
More severe kidney infections
You may need to go into the hospital if you are very sick and cannot take medicines by mouth or drink enough fluids. You may also be admitted to the hospital if you:
- Are an older adult
- Have kidney stones or changes in the anatomy of your urinary tract
- Have recently had urinary tract surgery
- Have cancer, diabetes, multiple sclerosis, spinal cord injury, or other medical problems
- Are pregnant and have a fever or are otherwise ill
At the hospital, you will receive fluids and antibiotics through a vein.
Some people have UTIs that do not go away with treatment or keep coming back. These are called chronic UTIs. If you have a chronic UTI, you may need stronger antibiotics or to take medicine for a longer time.
You may need surgery if the infection is caused by a problem with the structure of the urinary tract.
You could try taking:
- A supplement called D-mannose
- Cranberry juice or tablets
- A probiotic called lactobacillus
- Research suggests D-mannose might help prevent UTIs in women who are not pregnant.
- It’s not clear if cranberry products or lactobacillus help.
- Be aware that D-mannose and cranberry products can contain a lot of sugar.
Prevention of urinary tract infection
There are several measures that can be taken to reduce the risk of developing a UTI:
- Drink lots of water and urinate frequently.
- Avoid fluids such as alcohol and caffeine that can irritate the bladder.
- Urinate shortly after sex.
- Wipe from front to back after urinating and bowel movement.
- Keep the genital area clean.
- Showers are preferred to baths and avoid using oils.
- Sanitary pads or menstrual cups are preferred to tampons. If you want to buy menstrual cups, then there is an excellent selection on Amazon with thousands of customer reviews.
- Avoid using a diaphragm or spermicide for birth control.
- Avoid using any perfumed products in the genital area.
- Wear cotton underwear and loose-fitting clothing to keep the area around the urethra dry.
Individuals are advised to contact a doctor if they develop the symptoms of a UTI, especially if they have developed the symptoms of a potential kidney infection.