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A bladder infection is a bacterial infection of the bladder. It is also sometimes known as a urinary tract infection because the urinary tract includes the bladder, urethra, ureters, and kidneys.
Bladder infections are much more common in women than in men. It is estimated that more than 50 percent of women will experience a bladder infection at least once in their lifetime. Most are uncomplicated infections typically caused by the Escherichia coli (E. coli) bacterium.
The term “uncomplicated” is used to describe infections that occur in healthy women as opposed to “complicated” bladder infections that happen to people with other conditions, such as catheters, urinary stents, diabetes, pregnancy, or other causes.
Although an uncomplicated bladder infection is often easily treated with a short course of antibiotics, it can be considerably uncomfortable for the person who has it.
Bladder infections often occur when bacteria get into the urethra, the tube that carries urine out of the body, and then move into the bladder.
Once in the bladder, the bacteria can stick to the lining of the bladder, causing it to become inflamed, a condition known as cystitis. The bacteria can also move from the bladder into the kidneys, resulting in a kidney infection.
There are a number of factors that can increase the risk of getting a bladder infection, including:
- frequent sexual intercourse
- having sexual intercourse with a new partner
- using a diaphragm and a spermicide for birth control
- not urinating immediately after sexual intercourse
- having diabetes
- having a bladder or kidney infection within the past 12 months
- changes in the urinary system
The symptoms of a bladder infection can include:
- pain or burning when urinating
- urgent and frequent need to urinate, often passing small quantities of urine
- discomfort in the lower abdomen
- offensive-smelling urine
- cloudy urine
- blood in the urine
People with kidney infections have similar symptoms, but they may also have:
A doctor can usually diagnose a bladder infection after discussing the symptoms a person is experiencing and doing a urinalysis. This is a urine test that looks for the presence of white blood cells in the urine, and signs of inflammation, which indicates an infection.
If a kidney infection is suspected, the doctor may recommend a urine culture. A urine culture is a laboratory test used to identify the different bacteria that may be present in a urine sample.
Urine cultures are often recommended if the person:
- experiences symptoms that are not typical of a bladder infection
- gets frequent bladder infections
- has “resistant” bladder infections that do not improve with antibiotics
- does not begin to feel better within 24-48 hours after starting antibiotics
- is pregnant
People with uncomplicated bladder infections are usually treated with a short course of antibiotics. Treatment options vary, but the following are the most common prescriptions for uncomplicated cystitis:
- trimethoprim-sulfamethoxazole (Bactrim) – 160-800 milligrams (mg) twice daily for 3 days
- nitrofurantoin monohydrate – 100 mg twice daily for 5 – 7 days
- fosfomycin trometamol – 3 grams (g) in a single dose
A 3-day course of treatment has been found to be as efficient as a 7-day course of treatment and people experienced fewer side effects. Side effects usually stem from the overgrowth of yeast, which can cause a rash and yeast vaginitis. The 3-day course is also more cost efficient than the 7-day regime.
A single-dose treatment is also available, but it generally results in lower cure rates and more frequent recurrence.
Most people find that their symptoms begin to improve the day after beginning the treatment. Even if someone feels better, it is important that they take the full course of antibiotics in order to completely eliminate the infection. If they do not finish the whole dose, the infection may return, and it can be harder to treat the second time around.
If symptoms persist for more than 2 or 3 days after starting treatment, people should contact their doctor.
People with more complicated bladder infections will usually need to take antibiotics for 7-14 days. Complicated infections include those that occur during pregnancy, or in people who have diabetes or a mild kidney infection. It is also recommended that men with acute urinary infections take antibiotics for 7-14 days as well.
Less commonly, fluoroquinolones and beta-lactam antibiotics are used to treat more invasive infections. These antibiotics are effective, but they are not recommended for initial treatment because of concerns about bacterial resistance.
Given the worrying problem of antibiotic-resistant bacteria, doctors try to encourage women who experience regular bladder infections to use prevention strategies when possible. These strategies may include:
- Changing their method of birth control: Bladder infections appear to be more common in women who use spermicides and a diaphragm.
- Staying hydrated and urinating directly after sexual intercourse: This may help to wash out any bacteria that enter the bladder.
- Topically applying estradiol cream if postmenopausal: Postmenopausal women may benefit from using vaginal estrogen to reduce risk of infection. Estradiol cream is available to purchase online.
- Using a preventive antibiotic: This may be recommended if someone repeatedly develops bladder infections and has not responded to other preventive measures.
People can also help prevent bladder infections by including unsweetened cranberry juice, D-mannose, apple cider vinegar, ascorbic acid (vitamin C), and probiotics into their diets. Of these remedies, cranberry products and D-mannose appear to be the most popular.
Drinking unsweetened cranberry juice or taking cranberry supplements is often promoted as one way to help prevent frequent bladder infections. Compounds known as proanthocyanidins found in cranberries are thought to prevent bacteria from sticking to the walls of the urethra and bladder, reducing the risk of infection.
The recommended dose is 3 glasses of unsweetened cranberry juice daily, or 2 tablets daily, until the infection subsides.
Cranberry juice is available for purchase online.
D-mannose is a naturally occurring sugar found in certain fruits, such as cranberries and blueberries. A new study suggests that D-mannose is just as effective as antibiotics in preventing recurrent urinary tract infections in women.
The sugar attaches to any E. coli bacteria present and prevents them from sticking to the walls of the urinary tract or bladder. The bacteria are then flushed out on urination.
D-mannose is available in powder or capsule form. The recommended dose is 500 mg taken every 2 hours for 5 days. People who experience recurrent bladder infections could take a lower daily dose of D-mannose as a preventive measure.
Uncomplicated bladder infections are mainly treated with a short course of antibiotics. This treatment is highly effective, inexpensive, and most people tolerate it well. Typically, symptoms start to improve after 48 hours and are often resolved within 72 hours.
For people whose infection has spread to the kidneys, antibiotics are usually administered for 10-14 days. After this time, most infections get better without any further complications.