What is bladder infection

A bladder infection often called cystitis, is an infection of the urinary bladder caused by bacteria ¹. Bladder infections are the most common type of urinary tract infection (UTI) ². Most bladder infections are caused by normal bacterial flora entering the urinary tract via ascent through the urethra from the bowel, vagina, or perineum. It is not the presence, but rather the expression of the organism’s virulence factors which allow their adherence to the perineum and urethra. This is followed by migration into the bladder with invasion of the urothelium leading to symptoms secondary to the inflammatory response.

A urinary tract infection can develop in any part of your urinary tract, including your urethra, bladder, ureters, or kidneys. An infection in the urethra is called urethritis. Bacteria may travel up the ureters to multiply and infect the kidneys. A kidney infection is called pyelonephritis. If untreated, urinary tract infections can lead to kidney infection, so it’s important to visit your doctor for early management.

Normally, bacteria that enter the urinary tract are rapidly removed by the body before they cause symptoms. Your body has ways to defend against infection in the urinary tract. For example, urine normally flows from your kidneys, through the ureters to your bladder. Bacteria that enter your urinary tract are flushed out when you urinate. This one-way flow of urine helps to keep bacteria from infecting your urinary tract. However, sometimes bacteria overcome the body’s natural defenses and cause infection.

The urinary bladder is a hollow, collapsible muscular sac that stores and expels urine situated in the pelvic cavity posterior to the pubic symphysis. In males, it is
directly anterior to the rectum; in females, it is anterior to the vagina and inferior to the uterus (see Figure 1). Folds of the peritoneum hold the urinary bladder in position. When slightly distended due to the accumulation of urine, the urinary bladder is spherical. When it is empty, it collapses. As urine volume increases, it becomes pear shaped and rises into the abdominal cavity.

Most of the time, getting treatment right away for an infection in your urethra or bladder can prevent a kidney infection. A kidney infection can develop from a urinary tract infection that moves upstream to one or both of your kidneys. Kidney infections are often very painful and can cause serious health problems, so it’s best to get early treatment for a urinary tract infection.

When a bladder infection or other urinary tract infection is diagnosed and treated properly, most people won’t have complications.

Figure 1. Urinary bladder location

Figure 2. Urinary bladder anatomy

How common are bladder infections ?

Bladder infections are common, especially among women. Research suggests that at least 40 to 60 percent of women develop a UTI during their lifetime, and most of these infections are bladder infections. One in 4 women is likely to have a repeat infection ².

Who is more likely to develop a bladder infection ?

People of any age or sex can develop bladder infections, but women are at higher risk than men. Some people are more prone to getting these infections than others, especially those who have certain medical conditions or lifestyle factors.

You are more likely to develop a bladder infection if you:

• are sexually active
• are a woman who has gone through menopause
• are a woman who uses certain types of birth control, such as diaphragms or spermicide
• have trouble emptying your bladder completely, like people with a spinal cord injury or nerve damage around the bladder
• have a problem in your urinary tract that blocks, or obstructs, the normal flow of urine, such as a kidney stone or enlarged prostate
• have an abnormality of the urinary tract, such as vesicoureteral reflux (VUR)
• have diabetes or problems with your body’s immune, or natural defense, system
• recently used a urinary catheter
• had a urinary tract infection (UTI) in the past

In postmenopausal women, mechanical and/or physiologic factors that affect bladder emptying are strong risk factors for uti. Factors associated with bladder infection in this age group include:

• urinary incontinence
• cystocoele and large postvoid residual volumes
• atrophic vaginitis, and
• a history of urinary tract infections before menopause ³.

While rare, diverticular disease of the urethra may also present with symptoms of recurrent urinary tract infection.

Women are more likely to develop a bladder infection than men, mainly due to differences in anatomy:

• Women have a shorter urethra than men, which means bacteria have a shorter distance to travel to reach and infect a woman’s bladder.
• In women, the opening to the urethra is closer to the rectum, where the bacteria that cause bladder infections live.

What are the complications of bladder infections ?

If infections in the lower urinary tract, such as bladder infections, are not treated, they can lead to kidney infections. If you have a kidney infection, a health care professional will provide treatment to relieve your symptoms and help prevent complications.

Health care professionals routinely test pregnant women for bacteria in the urine because a bladder infection during pregnancy is more likely to become a kidney infection.

Complications from bladder infections are rare when you work with your health care provider to find the best treatment and complete it. If your infection is treated with antibiotics, it’s important to follow directions carefully and finish all the medicine, even after you start to feel better. If you stop taking antibiotics too soon, you may get another infection that is harder to treat.

What are bladder infection signs and symptoms

Symptoms of a bladder infection may include ⁴:

• A burning feeling when you urinate
• Frequent or intense urges to urinate, even when you have little urine to pass
• Passing frequent, small amounts of urine
• Urine that appears cloudy
• Urine that appears red, bright pink or cola-colored — a sign of blood in the urine
• Strong-smelling urine
• Pelvic pain, in women — especially in the center of the pelvis and around the area of the pubic bone

UTIs may be overlooked or mistaken for other conditions in older adults.

Seek medical care right away

• If you have symptoms of a bladder infection, see a health care professional right away, especially if you have severe pain in your back near your ribs or in your lower abdomen, along with vomiting and nausea, fever, or other symptoms that may indicate a kidney infection.

Kidney infections are often very painful and can cause serious health problems, so it’s best to get early treatment.

What causes a bladder infection ?

Most of the time a bladder infection is caused by bacteria that are normally found in your bowel. The bladder has several systems to prevent infection. For example, urination most often flushes out bacteria before it reaches the bladder. Urinary tract infections typically occur when bacteria enter the urinary tract through the urethra and begin to multiply in the bladder. Although the urinary system is designed to keep out such microscopic invaders, these defenses sometimes fail. When that happens, bacteria may take hold and grow into a full-blown infection in the urinary tract.

The most common urinary tract infections occur mainly in women and affect the bladder and urethra.

Infection of the bladder (cystitis). This type of urinary tract infection is usually caused by Escherichia coli (E. coli), a type of bacteria commonly found in the gastrointestinal (GI) tract. However, sometimes other bacteria are responsible.

Sexual intercourse may lead to bladder infection, but you don’t have to be sexually active to develop it. All women are at risk of bladder infection because of their anatomy — specifically, the short distance from the urethra to the anus and the urethral opening to the bladder.

Infection of the urethra (urethritis). This type of urinary tract infection can occur when gastrointestinal bacteria spread from the anus to the urethra. Also, because the female urethra is close to the vagina, sexually transmitted infections, such as herpes, gonorrhea, chlamydia and mycoplasma, can cause urethritis.

Bladder infection in men may be caused by:

• An enlarged prostate (benign prostatic hyperplasia, or BPH)
• Kidney stones
• Abnormal narrowing of the urethra (urethral stricture)
• Having a recent urinary tract procedure involving instrumentation, such as insertion of a tube to drain your bladder (catheterization) or a small camera to examine your bladder and urethra (cystoscopy)

Treatment of a bladder infection depends on the cause, but typically includes antibiotics.

Risk factors for bladder infection

Urinary tract infections are common in women, and many women experience more than one infection during their lifetimes. Risk factors specific to women for urinary tract infections include:

• Female anatomy. A woman has a shorter urethra than a man does, which shortens the distance that bacteria must travel to reach the bladder.
• Sexual activity. Sexually active women tend to have more urinary tract infections than do women who aren’t sexually active. Having a new sexual partner also increases your risk.
• Certain types of birth control. Women who use diaphragms for birth control may be at higher risk, as well as women who use spermicidal agents.
• Menopause. After menopause, a decline in circulating estrogen causes changes in the urinary tract that make you more vulnerable to infection.

Other risk factors for bladder infections include:

• Urinary tract abnormalities. Babies born with urinary tract abnormalities that don’t allow urine to leave the body normally or cause urine to back up in the urethra have an increased risk of urinary tract infections.
• Blockages in the urinary tract. Kidney stones or an enlarged prostate can trap urine in the bladder and increase the risk of urinary tract infections.
• A suppressed immune system. Diabetes and other diseases that impair the immune system — the body’s defense against germs — can increase the risk of urinary tract infections.
• Catheter use. People who can’t urinate on their own and use a tube (catheter) to urinate have an increased risk of urinary tract infections. This may include people who are hospitalized, people with neurological problems that make it difficult to control their ability to urinate and people who are paralyzed.
• A recent urinary procedure. Urinary surgery or an exam of your urinary tract that involves medical instruments can both increase your risk of developing a urinary tract infection.

Complications of bladder infection

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 bladder infection may include:

• Recurrent infections, especially in women who experience two or more urinary tract infections 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 urinary tract infection.
• 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 your urinary tract to your kidneys.

Prevention of bladder infection

You can take these steps to reduce your risk of urinary tract infections:

• Drink plenty of liquids, especially water. Drinking water helps dilute your urine and ensures that you’ll urinate more frequently — allowing bacteria to be flushed from your urinary tract before an infection can begin.
• Drink cranberry juice. Although studies are not conclusive that cranberry juice prevents UTIs ⁵. People who think they have a UTI should see a health care provider for a diagnosis and treatment. Don’t use cranberry products in place of proven treatments for infections. Drinking cranberry juice appears to be safe, although large amounts can cause stomach upset and may over time increase the risk of kidney stones.
• Wipe from front to back. Doing so after urinating and after a bowel movement helps prevent bacteria in the anal region from spreading to the vagina and urethra.
• Empty your bladder soon after intercourse. Also, drink a full glass of water to help flush bacteria.
• Avoid potentially irritating feminine products. Using deodorant sprays or other feminine products, such as douches and powders, in the genital area can irritate the urethra.
• Change your birth control method. Diaphragms, or unlubricated or spermicide-treated condoms, can all contribute to bacterial growth.

Diagnosis of bladder infection

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.

Treatment for bladder infection

Antibiotics usually are the first line treatment for urinary tract infections. Which drugs are prescribed and for how long depend on your health condition and the type of bacteria found in your urine.

Simple infection

Drugs commonly recommended for simple UTIs include:

• Trimethoprim/sulfamethoxazole (Bactrim, Septra, others)
• Fosfomycin (Monurol)
• Nitrofurantoin (Macrodantin, Macrobid)
• Cephalexin (Keflex)
• Ceftriaxone

The group of antibiotic medicines known as fluoroquinolones — such as ciprofloxacin (Cipro), levofloxacin (Levaquin) and others — isn’t commonly recommended for simple UTIs, as the risks of these medicines generally outweigh the benefits for treating uncomplicated UTIs. In some cases, such as a complicated UTI or kidney infection, your doctor might prescribe a fluoroquinolone medicine if no other treatment options exist.

Often, symptoms clear up within a few days of treatment. But you may need to continue antibiotics for a week or more. Take the entire course of antibiotics as prescribed.

For an uncomplicated UTI that occurs when you’re otherwise healthy, your doctor may recommend a shorter course of treatment, such as taking an antibiotic for one to three days. But whether this short course of treatment is enough to treat your infection depends on your particular symptoms and medical history.

Your doctor may also prescribe a pain medication (analgesic) that numbs your bladder and urethra to relieve burning while urinating, but pain usually is relieved soon after starting an antibiotic.

Frequent infections

If you have frequent UTIs, your doctor may make certain treatment recommendations, such as:

• Low-dose antibiotics, initially for six months but sometimes longer
• Self-diagnosis and treatment, if you stay in touch with your doctor
• A single dose of antibiotic after sexual intercourse if your infections are related to sexual activity
• Vaginal estrogen therapy if you’re postmenopausal

Severe infection

For a severe UTI, you may need treatment with intravenous antibiotics in a hospital.

Home treatments

• Drink a lot of liquids and urinate often to speed healing. Water is best. Talk with a health care professional if you can’t drink a lot of liquids due to other health problems, such as urinary incontinence, urinary frequency, or heart or kidney failure.
• Avoid drinks that may irritate your bladder. Avoid coffee, alcohol, and soft drinks containing citrus juices or caffeine until your infection has cleared. They can irritate your bladder and tend to aggravate your frequent or urgent need to urinate.
• A heating pad on your back or abdomen may help you manage pain from a kidney or bladder infection.

Recurrent bladder infections

Several factors make women more likely to get recurrent bladder infections, a type of urinary tract infection. These factors include:

• Kidney or bladder stones
• Bacteria entering the urethra during intercourse
• Changes in estrogen levels during menopause
• An abnormal urinary tract shape or function
• An inherited risk of developing bladder infections (genetic predisposition)

If you’ve had two or more culture-documented bladder infections during a six-month period, consider seeing a urologist — a doctor who specializes in diagnosing and treating urinary tract diseases.

To figure out what’s causing the repeat infections, your urologist may recommend a:

• Urine culture test of a sample obtained with a catheter
• Visual exam of the bladder and urethra with a lighted scope (cystoscopy)
• Computerized tomography (CT) scan of the urinary tract

Treatment is directed at the underlying cause, when possible. If your doctor can’t find a cause, one of these options may help:

• A long-term, low-dose antibiotic for as long as six months to two years
• Intermittent or self-directed antibiotic therapy — for instance, taking an antibiotic after intercourse or starting a course of antibiotics supplied in advance by your doctor at the first sign of a UTI
• Vaginal estrogen therapy — if you don’t already take oral estrogen — for signs or symptoms related to vaginal dryness (atrophic vaginitis) after menopause

Expert opinions vary on whether certain lifestyle changes reduce the risk of bladder infection, but it may be helpful to:

• Drink plenty of liquids, especially water, to help flush out bacteria
• Urinate often, especially when you feel the need
• Wipe from front to back after urination or a bowel movement
• Take showers rather than baths
• Gently wash the skin around your vagina and anus daily using a mild soap and plenty of water
• Use forms of birth control other than a diaphragm and spermicides
• Empty your bladder as soon as possible after intercourse
• Avoid deodorant sprays or scented feminine products in the genital area

Studies show conflicting results on whether cranberry juice may have infection-fighting properties that help prevent urinary tract infections. But, there’s likely little harm in trying cranberry juice to see if it helps you — just watch the calories. For most people, drinking cranberry juice is safe, but some people report an upset stomach or diarrhea.

1. Bladder Infection (Urinary Tract Infection—UTI) in Adults. National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/urologic-diseases/bladder-infection-uti-in-adults/definition-facts[↩]
2. Franco AV. Recurrent urinary tract infections. Best Practice & Research Clinical Obstetrics and Gynaecology. 2005;19:861–873.[↩][↩]
3. Raz R, Gennesin Y, Wasser J, et al. recurrent urinary tract infections in postmenopausal women. clin infect Dis 2000;30:152–6.[↩]
4. Urinary tract infection (UTI). Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/urinary-tract-infection/symptoms-causes/syc-20353447[↩]
5. Cranberry. National Center for Complementary and Integrative Health. https://nccih.nih.gov/health/cranberry[↩]