What Is Urinary Tract Infection? What Causes Urinary Tract Infection?

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Main Category: Urology / Nephrology
Also Included In: Infectious Diseases / Bacteria / Viruses
Article Date: 26 May 2010 - 0:00 PDT

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A urinary tract infection (UTI) is a bacterial infection that affects the urinary system - the organ system that produces, stores, and eliminates urine. The urinary system includes two kidneys, two ureters, the bladder, the urethra and two sphincter muscles - a urinary tract infection can affect any part of the urinary system ("urinary tract" and "urinary system" refer to the same thing).

The infection is usually caused by bacteria called Escherichia coli. Urine contains a range of salts, fluids and waste produces, but does not usually have bacteria in it. Bacteria entering the bladder or kidney can reproduce rapidly in the urine, causing a UTI (urinary tract infection).

Cystitis, often referred to as a bladder infection, is the most common type of UTI. A kidney infection, also known as pyelonephritis is potentially more serious. Infections of the bladder and/or urethra are known as lower urinary tract infections; if it occurs in the kidneys or ureters they are known as upper urinary tract infections.

Urinary tract infections are generally easily and effectively treated with a short course of antibiotics. However, infection can cause discomfort, with the patient experiencing pain during urination, a frequent urge to urinate, and cloudy urine.

Females are more susceptible to UTIs than males. According to the National Health Service (NHS), UK, 1 in every 3 women will have a UTI before she is 24 years old, and about half of all females will have at least one UTI during their lifetime. In the UK approximately 1 in every 2,000 otherwise healthy men develops a UTI.

According to Medilexicon's medical dictionary:

Urinary tract infection is microbial infection, usually bacterial, of any part of the urinary tract; may involve the parenchyma of the kidney, the renal pelvis, the ureter, the bladder, the urethra or combinations of these organs. Often, the entire urinary tract is affected; the most common organism causing such infection is Escherichia coli.

What are the signs and symptoms of urinary tract infection?

A symptom is something the patient senses and describes, while a sign is something other people, such as the doctor notice. For example, drowsiness may be a symptom while dilated pupils may be a sign.

Signs and symptoms of a urinary tract infection depend on whether the lower or upper urinary tract is affected.

Lower urinary tract infection (affects bladder and/or urethra) signs and symptoms:

• Cloudy urine
• The urine may have an unpleasant smell
• Hematuria - blood in urine
• Frequent need to urinate - this may occur during the waking hours, sleeping hours, or both
• Holding the urine in may become harder to do
• Discomfort and sometimes pain when urinating
• Abdominal pain
• Back pain
• General malaise; generally feeling unwell
• Tenderness around the pelvic area

Upper urinary tract infection (affects kidneys and/or ureters):

• Fever, usually high (at least 38C or 100.4F)
• Shivering
• Vomiting
• Nausea
• Diarrhea
• Pain on the side (flank), upper back or groin - this may become more uncomfortable when urinating
• Lower UTI symptoms - if the infection spreads to the lower urinary tract, the patient may also have those symptoms.

What are the risk factors for urinary tract infection?

A risk factor is something which increases the likelihood of developing a condition or disease. For example, obesity significantly raises the risk of developing diabetes type 2. Therefore, obesity is a risk factor for diabetes type 2.

Gender - females are significantly more likely to develop a UTI than males. Females have a shorter urethra, making the distance to the bladder shorter, and the likelihood of the infection moving upwards to the bladder greater. A woman's urethra opening is much nearer the anus than a man's. Consequently, there is a higher risk of bacteria entering the urethra from the anus.

Sexual activity - females who are sexually active are more likely to have a UTI.

Some forms of birth control - females who use diaphragms for birth control tend to be more susceptible to UTIs.

Age - post-menopausal women tend to develop UTIs more frequently than other women. During the menopause women produce less mucus in the vaginal area. This mucus stops the bacteria from multiplying. Women on HRT (hormone replacement therapy) have a lower risk of developing cystitis compared to menopausal women not on HRT. During the menopause the lining of a woman's urethra gets thinner as her levels of estrogen drop. The thinner the lining becomes, the higher the chances are of infection and damage.

Kidney problems - people with kidney stones, and some other kidney problems are more likely to develop infections.

Some chronic illnesses - especially those that weaken the immune system may increase the risk of developing UTIs, such as diabetes.

Long-term catheter use - patients with a urinary catheter have a higher risk of UTI (if used for a long time).

What are the causes of urinary tract infection?

Most commonly, a urinary tract infection occurs when gastrointestinal bacteria (bacteria in the gut) enter through the urethra and start multiplying in the bladder. Our defense system is designed to keep such germs out, but sometimes they fail, and bacteria may take hold and multiply into an infection.

The most common UTIs occur mainly in females and affect the urethra and bladder (males can also become infected):

• Cystitis (bladder infection) - refers to inflammation of the lining of the bladder. It usually occurs when the normally sterile urethra and bladder (lower urinary tract) are infected by bacteria and become irritated and inflamed. Cystitis is fairly common, affects women more than men (but can affect either sex).
  
  
• Urethritis (infection of the urethra) - more common in females because the opening of the urethra is closer to the anus (compared to males), making it easier for gastrointestinal bacteria to infect the urethra.

Other possible urinary tract infections include:

• Ureteritis (infection of the ureters) - the tubes from the kidneys to the bladder become infected.
• Pyelonephritis (infection of the kidneys)

Diagnosing urinary tract infections

Lower urinary tract infection (Lower UTI) - according to the National Health Service (NHS), a female patient with typical lower UTI symptoms will not generally need to have the diagnosis confirmed with diagnostic tests, because lower UTI causes a distinctive pattern of symptoms. In other words, if the GP asks the patient questions which are answered in a certain way, he/she can usually make a reasonably accurate diagnosis.

Further diagnostic tests may be needed if:

• The patient is male - UTI is rare in men. Therefore, the doctor has to make sure that other possible causes have been ruled out.
• Upper UTI - if the doctor suspects upper urinary tract infection (upper UTI), which have a higher risk of complications; a more careful assessment may be required of the urinary tract.
• Pregnancy - if the patient is pregnant, the doctor will probably order further tests.
• Blood in urine - partly to rule out other illnesses and conditions, such as bladder cancer.
• Vulnerable individuals - mainly patients with weakened immune systems, such as those with diabetes, or possibly individuals receiving cancer therapy.

Possible diagnostic tests may include:

Urine test - to detect the presence of bacteria. A urine test will also help the doctor decide which antibiotic to prescribe.

Intravenous urogram (IVU) - a special dye which shows up on an X-ray is injected into the patient. The radiologist observes how the dye travels through the urinary system and problems are detected.

Cytoscopy - the doctor inserts a long-thin instrument (a cystoscope) into the urethra in order to look inside the urethra and bladder. There is a lense at the end of the cystoscope, allowing the doctor to focus on the inner surfaces of the urinary tract. Some cystoscopes use flexible glass fibers (optical fibers) that carry an image to a viewing piece. This procedure lasts from 5 to 10 minutes. A cytoscopy is effective in detecting bladder cancer.

What are the treatment options for urinary tract infection?

Treatment depends on whether it is an upper or lower urinary tract infection. Cases of lower UTI and mild cases of upper UTI can be treated at home using antibiotics. Patients with more severe upper UTI, as well as those with weakened immune systems may have to be hospitalized.

Lower urinary tract infection (lower UTI) treatment - treatment is usually at home and involves taking an antibiotic course that lasts from 3 to 7 days. Course length is linked to the patient's risk of developing complications.

• Trimethoprim - an antibiotic commonly used for lower UTI cases. Side effects may include nausea, vomiting, skin rash and itchy skin.
• Painkillers - for abdominal pain the patient may take OTC (over-the-counter, no prescription required) painkillers, such as ibuprofen.

Upper urinary tract infection (upper UTI) treatment:

• At home - this usually involves a longer course of antibiotics, between 7 and 14 days. Course length is linked to complications risk.
  
  
  • Co-amoxiclav or ciprofloxacin - commonly prescribed unless the patient is pregnant. Pregnant patients will probably have to take cephalexin. As they may cause drowsiness, patients should not drive or operate heavy or complex machinery.
  • Fever and dehydration - the patient should consume plenty of liquids.
  • Painkillers - NSAIDs (non-steroidal anti-inflammatory drugs), such as ibuprofen or naproxen should not be used as they may increase the risk of a kidney complication.
• In hospital - the following types of patients with an upper UTI may be hospitalized:
  • Pregnant women
  • Seniors
  • If the patient is vomiting
  • If pain is severe
  • If the person is dehydrated
  • If urination is severely reduced
  • If the individual has a history of kidney disease
  • If the individual has HIV/AIDS
  • If the patient has a kidney problem, such as a kidney stone
  • If the patient has cancer
  • If the patient has sickle-cell anemia
  • If this is a recurrence of upper UTI
  • Patients undergoing radiotherapy or chemotherapy
  In most cases the patient will receive fluids and possibly antibiotics through a drip. They will be carefully monitored with regular urine and blood tests - these tests also help gauge how effective the antibiotics have been.
  
  According to the National Health Service (NHS), UK, the majority of patients respond well to treatment and can go home within three to seven days.

Treatment for recurring urinary tract infections (recurring UTIs) - the patient may need further treatment to prevent urinary tract damage.

Experts say that recurring UTIs are probably due to the urethra becoming irritated after sexual intercourse. In such cases the patient will be asked to take an antibiotic tablet after each episode of sexual intercourse.

Women with recurrent UTIs who use a diaphragm or spermicide-coated condoms as their main contraception method should consider other forms of contraception, such as the pill.

Individuals whose recurring upper UTIs are not linked to sexual activity may be prescribed a low-dose antibiotic for daily use.

Methenamine hippurate is a medication which alters the chemical composition of urine, making it a less attractive environment for bacteria. It is an alternative to antibiotics. Side effects may include indigestion, itchy skin and skin rashes. Methenamine hippurate is less effective than antibiotics in preventing upper UTI recurrences - therefore, it tends to be used solely by individuals who either cannot or don't want to take antibiotics.

What are the possible complications of urinary tract infection (UTI)?

With prompt and proper treatment the chances of complications are tiny. However, untreated UTIs can eventually lead to acute or chronic kidney infections, resulting in possibly permanent kidney damage.

A pregnant woman with a UTI has a higher risk of delivering her baby early, as well as having a low-weight baby at birth.

Recurrences - females who have at least 3 UTIs will probably continue having more of them.

Prevention

Not all cases of UTI are preventable. However, there are some things we can do to reduce the risk.

Cranberry juice or cranberry capsules - studies have shown that drinking cranberry juice helps reduce the risk of developing UTIs. For those with recurring UTIs stronger capsules are recommended. Patients taking Warfarin should not take cranberry juice or capsules.

Constipation - can increase the risk of developing a UTI. Therefore, constipation should be treated quickly, or prevented.

Urination - do not hold urine in; go whenever you feel like going.

Bottom wiping - after going to the toilet, wipe your bottom from front to back.

Genital hygiene - wash the genitals every day. Wash the genitals before having sex. Empty the bladder after having sex.

Avoid irritating feminine products - such as deodorant sprays, douches, scented soaps and powders may irritate the urethra.

Written by Christian Nordqvist


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