What is Asymptomatic Bacteriuria?
“Asymptomatic bacteriuria” is a term used when someone has bacteria in their urine but doesn’t feel sick or show any signs of a urinary tract infection. This condition is pretty common, especially in older adults. While it’s rare in young children, its occurrence increases with age. It’s found in up to 15% or more in people between 65 to 80 years old, and up to 40-50% in people over 80.
Interestingly, most people with asymptomatic bacteriuria never actually develop a full-blown urinary tract infection or face any negative outcomes because of it. In a time when we’re encouraged to cut back on unnecessary antibiotic use, a crucial question is: who should be treated for asymptomatic bacteriuria?
Generally, most people with this condition don’t need treatment. However, there are a few exceptions. For example, evidence suggests pregnant women with asymptomatic bacteriuria should be treated. Similarly, people about to undergo certain surgeries involving the urinary tract or those in the first three months after a kidney transplant should probably receive treatment for asymptomatic bacteriuria as well.
What Causes Asymptomatic Bacteriuria?
The exact cause of asymptomatic bacteriuria, a condition where bacteria are present in the urine without causing symptoms, isn’t completely understood yet. This condition is more likely to occur in women than in men, and the reason could be the shorter urethra in women. This shorter distance allows bacteria from the urethra and surrounding area to reach the bladder more easily.
Interestingly, most women may experience a temporary increase in the bacteria in their urine after sex, but these women typically don’t end up with infections because the body’s natural defenses often prevent any issues from developing.
In older people, it has been suggested that the increased risk of asymptomatic bacteriuria could come from the bladder not fully emptying when they urinate.
Risk Factors and Frequency for Asymptomatic Bacteriuria
Asymptomatic bacteriuria, which is when bacteria is present in the urine without causing symptoms, is a condition often found in medical check-ups. Its occurrence varies with different age groups and genders. The incidence rises as people age, being less common in children but more common in the elderly, especially those in long-term care. Women are more likely to have asymptomatic bacteriuria than men, at any age. The most common bacteria found in these cases is Escherichia coli.
- Asymptomatic bacteriuria is a condition where bacteria is in the urine but doesn’t cause symptoms.
- In infants and toddlers, less than 0.5% have this condition.
- The occurrence is 5% or less among healthy women before menopause.
- The incidence increases with age, affecting 15% or more in women and men between 65-80 years.
- Further, the condition’s incidence increases to 40% to 50% among long-term care residents over 80 years old.
- Regardless of age, women are more likely to have asymptomatic bacteriuria than men.
- Escherichia coli is the most common bacteria found in these cases.
Signs and Symptoms of Asymptomatic Bacteriuria
Asymptomatic bacteriuria is a condition where there are bacteria in the urine but no noticeable symptoms. It’s a different scenario compared to symptomatic bacteriuria or urinary tract infections where symptoms are present. Certain conditions can make a person more likely to have asymptomatic bacteriuria. These include:
- Blocked urinary tract caused by conditions such as stones, an enlarged prostate, or cystocele,
- Fecal contamination of the area around the anus, particularly in women,
- Use of urinary catheters for a long time, and
- Frequent procedures or tests that involve the urinary tract.
Testing for Asymptomatic Bacteriuria
Asymptomatic bacteriuria is a health condition that can be identified by conducting a urine culture test. The test either uses a carefully collected clean-catch urine sample or a catheterized specimen. The Infectious Diseases Society of America (IDSA) provides guidelines for diagnosing this condition through these tests.
With a clean catch urine sample:
* For women, the same kind of bacteria needs to be found in two consecutive samples, and they should be present in considerable quantities, at least 100,000 colonies in each ml of urine.
* For men, one single test should reveal one kind of bacteria in the same number as for women (100,000 colonies per ml of urine).
If a catheterized specimen is used:
* For both women and men, one sample should show at least 100 colonies of one type of bacteria per ml of urine.
Sometimes, a quick urine test (urine dipstick) is used to detect leukocyte esterase. This test can help identify a urine infection, but it does not identify asymptomatic bacteriuria specifically since other urinary tract disorders can cause similar results. Another quick test detects nitrites, but it also does not provide a specific diagnosis due to several associated limitations. Using both these tests together can be more helpful to detect asymptomatic bacteriuria than using any of them alone. Examination of urine under a microscope can also be useful to detect bacteria in urine, but it does not indicate the quantity of bacteria.
Screening for asymptomatic bacteriuria is important for pregnant women, and using a urine culture test is recommended. The best time for this screening and how often it should be done during pregnancy isn’t clear so far, but it’s usually suggested at the end of the first pregnancy trimester.
Generally, asymptomatic bacteriuria is not commonly screened for, except for in some specific situations. These include patients undergoing certain urological procedures that may cause bleeding in the urinary tract tissues and patients who have undergone kidney transplantation within the past three months.
Treatment Options for Asymptomatic Bacteriuria
Most people without symptoms of a urinary tract infection, despite having bacteria in their urine (a condition known as asymptomatic bacteriuria), tend not to develop a full-blown infection. They also don’t experience any negative effects from having these bacteria. This includes children, people with diabetes, older adults, people with spinal cord injuries, and people who use urinary catheters.
Giving these groups antibiotics to treat their asymptomatic bacteriuria is not helpful and does not reduce their chances of developing a urinary tract infection. It also doesn’t increase their chances of survival. Instead, it raises their risk of having side effects from the antibiotics and makes them more likely to develop bacteria that can resist these medications.
However, treating pregnant women who have bacteria in their urine but no symptoms has been found to be beneficial. This treatment reduces their chances of developing a kidney infection, having a low-birthweight baby, and giving birth prematurely. Also, patients who are going to have certain urologic procedures that might cause bleeding in the urinary tract lining, like a prostate resection, and kidney transplant patients in their first three months post-transplant should be treated. Treatment in these cases can lower their risk of getting a symptomatic urinary tract infection.
Treatment choices should be based on urine laboratory test results to identify which bacteria are present and what antibiotics they’re sensitive to. Antibiotics that are safe to use in pregnancy include amoxicillin, amoxicillin/clavulanate, cefuroxime, cephalexin, and nitrofurantoin. For pregnant women, the treatment should last between 3 to 7 days, and they should have at least one follow-up urine test afterwards.
What else can Asymptomatic Bacteriuria be?
When a doctor is diagnosing symptoms related to the urinary and genital tract, they may consider various different conditions that might be causing the symptoms. Some of these possibilities are:
- Acute pyelonephritis – a sudden and severe kidney infection
- Bladder cancer
- Chlamydia – a sexually transmitted disease that can infect the urinary and genital areas
- Nonbacterial cystitis – inflammation of the bladder that’s not caused by bacteria
- Herpes simplex – a virus that can cause sores in the genital area
- Interstitial cystitis – a chronic condition causing bladder pressure and pain
- Pelvic inflammatory disease – an infection of a woman’s reproductive organs
- Renal and perirenal abscess – a pocket of pus around or in the kidneys
- Urethritis – inflammation of the urethra, the tube that carries urine from the bladder to outside the body
- Vaginitis – inflammation of the vagina that can result in discharge and itching
The physician has to carefully analyze the patient’s symptoms and possibly perform several tests to accurately identify the cause.
