Urinary tract infections (UTIs) are very common – particularly in women, babies and older people. Around one in two women and one in 20 men will get a UTI in their lifetime.
The kidneys control the amount of water in the blood and filter out waste products to form urine. Each kidney has a tube called a ureter, which joins the kidney to the bladder. The urine leaves the kidneys through the ureters and enters the bladder. The bladder ‘signals’ the urge to urinate and urine leaves the body through a tube called the urethra. The urinary system is designed to minimise the risk of serious infection in the kidneys. It does this by preventing the urine from flowing back up into the kidneys from the bladder. Most urinary infections are confined to the bladder and, while causing symptoms, are not serious or life threatening.
Types of urinary tract infections (UTIs)
UTIs are caused by micro-organisms or germs, usually bacteria. The different types of UTI can include:
- cystitis – infection of the bladder. Cystitis is the most common lower urinary tract infection
- urethritis – infection of the urethra
- pyelonephritis – infection of the kidneys
- vaginitis – infection of the vagina.
Symptoms of UTIs
Common symptoms of UTIs include:
- wanting to urinate more often and urgently, if only a few drops
- burning pain or a ‘scalding’ sensation when urinating
- a feeling that the bladder is still full after urinating
- pain above the pubic bone
- cloudy, bloody or very smelly urine.
Symptoms of kidney infections
If infection reaches the kidneys, prompt medical attention is needed. In addition to the general symptoms of UTIs, a person with a kidney infection can also experience:
- chills
- fever
- loin (lower abdominal) pain
- pain in the back
- vomiting.
Causes of UTIs
Bacteria do not normally live in the urinary tract. When bacteria enter the urinary tract and multiply, they can cause a UTI.
There are many germs that can cause urine infections or cystitis. The most common germ causing urinary tract infections is found in your digestive system, Escherichia coli (E.coli). E.coli can easily spread to the urethra and stick to the lining of your urinary system.
Germs such as Mycoplasma and Chlamydia can cause urethritis in both men and women. These germs can be passed on during sexual intercourse so both partners need medical treatment to avoid re-infection.
Some people may be at higher risk of infections due to the urinary flow being blocked or when the urine flows back up from the bladder to the kidneys.
Risk factors for developing UTIs
Urinary tract infections in women
UTIs are common, particularly with increasing age. Women are more likely to get a UTI than men. Nearly 1 in 3 women will have a UTI needing treatment before the age of 24.
In women, the urethra is short and straight, making it easier for germs to travel into the bladder. For some women, UTIs relate to changes in their hormonal levels. Some are more likely to get an infection during certain times in their menstrual cycle, such as just before a period or during pregnancy.
In older women, the tissues of the urethra and bladder become thinner and drier with age as well as after menopause or a hysterectomy. This can be linked to increased UTIs.
During pregnancy, the drainage system from the kidney to the bladder widens so urine does not drain as quickly. This makes it easier to get a UTI. Sometimes germs can move from the bladder to the kidney causing a kidney infection. UTIs during pregnancy can result in increased blood pressure, so it is very important to have them treated as soon as possible.
Women are more at risk of repeated UTIs if they:
- use spermicide jelly or diaphragm for contraception
- have had a new sexual partner in the last year (an increase in sexual activity may trigger symptoms of a UTI in some women)
- had their first UTI at or before 15 years of age
- have a family history of repeated UTIs, particularly their mother
- suffer from constipation
Urinary tract infections in men
Men can get UTIs, particularly if they have trouble with urine flow. Older men who experience prostatitis (an inflammation of the prostate) are at a higher risk. If the bladder is not emptying properly, the build up of
urine makes it more difficult to cure the infection.
A small number of young men may get a UTI. In males, this is usually the result of a sexually transmitted disease.
Urinary tract infections and diabetes
People with diabetes are at increased risk of having UTIs as their urine may have a high glucose (sugar) content, which makes it easier for bacteria to multiply. Diabetes may also change the body’s immune (defence) system making it harder to fight a UTI. The risk of developing a UTI increases as diabetes progresses.
Urinary tract infections in older people
Chronic conditions, some medications, and problems with incontinence put older people at an increased risk for developing UTIs. People using bladder catheters are also more likely to develop a UTI.
Urinary tract infections in babies and young children
Babies and children are at risk of UTIs. These infections always need to be investigated as they may indicate a serious underlying condition, such as urinary reflux. Reflux is caused by a bladder valve problem allowing urine to flow back into the kidneys from the bladder. Reflux can cause the urine to stay inside the body increasing the risk of infection. It may lead to kidney scarring, which in turn leads to high blood pressure and sometimes kidney problems.
Prevention of UTIs
Although not always backed up by clinical research, some women have found some suggestions useful in reducing their risk of developing urinary tract infections, including:
- Drink plenty of water and other fluids to flush the urinary system.
- Treat vaginal infections such as thrush or trichomonas quickly.
- Avoid using spermicide-containing products, particularly with a diaphragm contraceptive device.
- Go to the toilet as soon as you feel the urge to urinate, rather than holding on.
- Wipe yourself from front to back (urethra to anus) after going to the toilet.
- Empty your bladder after sex.
- Avoid constipation.
Cranberries (usually as cranberry juice) have been used to prevent UTIs. Cranberries contain a substance that can prevent the E. coli bacteria from sticking to the urinary tract lining cells. However, recent research has shown that cranberry juice does not have a significant benefit in preventing UTIs, and most people are unable to continue drinking the juice on a long-term basis. Let your doctor know if you are having cranberry juice as it can alter the effectiveness of some antibiotics.
Treatment for UTIs
It is important to seek medical attention if you think you may have a UTI – particularly if you think you may have a bladder or kidney infection, both of which are very serious conditions. Early treatment of urinary infection can help to prevent infection spreading to the bladder or kidneys.
Your doctor will test your urine to check which micro-organism is present. Urinary tract infections usually respond quickly and well to antibiotics.
Where to get help
Understanding pyelonephritis
Acute pyelonephritis is a sudden and severe kidney infection. It causes the kidneys to swell and may permanently damage them. Pyelonephritis can be life-threatening.
When repeated or persistent attacks occur, the condition is called chronic pyelonephritis. The chronic form is rare, but it happens more often in children or people with urinary obstructions.
Symptoms usually appear within two days of infection. Common symptoms include:
Other symptoms can include:
- shaking or chills
- nausea
- vomiting
- general aching or ill feeling
- fatigue
- moist skin
- mental confusion
Symptoms may be different in children and older adults than they are in other people. For example, mental confusion is common in older adults and is often their only symptom.
People with chronic pyelonephritis may experience only mild symptoms or may even lack noticeable symptoms altogether.
The infection usually starts in the lower urinary tract as a urinary tract infection (UTI). Bacteria enter the body through the urethra and begin to multiply and spread up to the bladder. From there, the bacteria travel through the ureters to the kidneys.
Bacteria such as E. coli often cause the infection. However, any serious infection in the bloodstream can also spread to the kidneys and cause acute pyelonephritis.
Any problem that interrupts the normal flow of urine causes a greater risk of acute pyelonephritis. For example, a urinary tract that’s an unusual size or shape is more likely to lead to acute pyelonephritis.
Also, women’s urethras are much shorter than men’s, so it’s easier for bacteria to enter their bodies. That makes women more prone to kidney infections and puts them at a higher risk of acute pyelonephritis.
Other people who are at increased risk include:
- anyone with chronic kidney stones or other kidney or bladder conditions
- older adults
- people with suppressed immune systems, such as people with diabetes, HIV/AIDS, or cancer
- people with vesicoureteral reflux (a condition where small amounts of urine back up from the bladder into the ureters and kidneys)
- people with an enlarged prostate
Other factors that can make you vulnerable to infection include:
Chronic pyelonephritis
Chronic forms of the condition are more common in people with urinary obstructions. These can be caused by UTIs, vesicoureteral reflux, or anatomical anomalies. Chronic pyelonephritis is more common in children than in adults.
A doctor will check for fever, tenderness in the abdomen, and other common symptoms. If they suspect a kidney infection, they will order a urine test. This helps them check for bacteria, concentration, blood, and pus in the urine.
Imaging tests
The doctor may also order an ultrasound to look for cysts, tumors, or other obstructions in the urinary tract.
For people who don’t respond to treatment within 72 hours, a CT scan (with or without injectable dye) may be ordered. This test can also detect obstructions within the urinary tract.
Radioactive imaging
A dimercaptosuccinic acid (DMSA) test may be ordered if your doctor suspects scarring as a result of pyelonephritis. This is an imaging technique that tracks an injection of radioactive material.
A healthcare professional injects the material through a vein in the arm. The material then travels to the kidneys. Images taken as the radioactive material passes through the kidneys show infected or scarred areas.
Antibiotics are the first course of action against acute pyelonephritis. However, the type of antibiotic your doctor chooses depends on whether or not the bacteria can be identified. If not, a broad-spectrum antibiotic is used.
Although drugs can cure the infection within 2 to 3 days, the medication must be taken for the entire prescription period (usually 10 to 14 days). This is true even if you feel better.
The antibiotic options are:
- levofloxacin
- ciprofloxacin
- co-trimoxazole
- ampicillin
Hospital admission
In some cases, drug therapy is ineffective. For a severe kidney infection, your doctor may admit you to the hospital. The length of your stay depends on the severity of your condition and how well you respond to treatment.
Treatment may include intravenous hydration and antibiotics for 24 to 48 hours. While you’re in the hospital, doctors will monitor your blood and urine to track the infection. You’ll likely receive 10 to 14 days’ worth of oral antibiotics to take after you’re released from the hospital.
Surgery
Recurrent kidney infections may result from an underlying medical problem. In those cases, surgery may be required to remove any obstructions or to correct any structural problems in the kidneys. Surgery may also be necessary to drain an abscess that doesn’t respond to antibiotics.
In cases of severe infection, a nephrectomy may be necessary. In this procedure, a surgeon removes part of the kidney.
Pregnancy causes many temporary changes in the body, including physiological changes in the urinary tract. Increased progesterone and increased pressure on the ureters can result in an increased risk of pyelonephritis.
Pyelonephritis in pregnant women typically requires hospital admission. It can threaten the lives of both mother and baby. It can also increase the risk of premature delivery. Pregnant women are treated with beta-lactam antibiotics for at least 24 hours until their symptoms improve.
To prevent pyelonephritis in pregnant women, a urine culture should be conducted between the 12th and 16th weeks of pregnancy. A UTI that doesn’t have symptoms can lead to the development of pyelonephritis. Detecting the UTI early can prevent kidney infection.
According to the American Urological Association, in the United States, more than one million trips to the pediatrician are made each year for pediatric UTIs. Girls are at increased risk if over one year old. Boys are at greater risk if under one, especially if they’re uncircumcised.
Children with UTIs often have fever, pain, and symptoms related to the urinary tract. A doctor should address these symptoms immediately before they can develop into pyelonephritis.
Most children can be treated with oral antibiotics in an outpatient manner. Learn more about UTIs in children.
A possible complication of acute pyelonephritis is chronic kidney disease. If the infection continues, the kidneys may be permanently damaged. Although rare, it’s also possible for the infection to enter the bloodstream. This can result in a potentially deadly infection called sepsis.
Other complications include:
- recurring kidney infections
- the infection spreading to areas around the kidneys
- acute kidney failure
- kidney abscess
Pyelonephritis can be a serious condition. Contact your doctor as soon as you suspect that you have pyelonephritis or a UTI. This condition requires prompt medical attention, so the earlier you start treatment, the better.