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Bacteriuria is the presence of
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...
in
urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra. Cellul ...
. Bacteriuria accompanied by symptoms is a
urinary tract infection A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidne ...
while that without is known as asymptomatic bacteriuria. Diagnosis is by
urinalysis Urinalysis, a portmanteau of the words ''urine'' and ''analysis'', is a panel of medical tests that includes physical (macroscopic) examination of the urine, chemical evaluation using urine test strips, and microscopic examination. Macroscopic e ...
or urine culture. ''
Escherichia coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Esc ...
'' is the most common bacterium found. People without symptoms should generally not be tested for the condition. Differential diagnosis include
contamination Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural environment, workplace, etc. Types of contamination ...
. If symptoms are present treatment is generally with
antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and preventio ...
. Bacteriuria without symptoms generally does not require treatment. Exceptions may include pregnant women, those who have had a recent
kidney transplant Kidney transplant or renal transplant is the organ transplant of a kidney into a patient with end-stage kidney disease (ESRD). Kidney transplant is typically classified as deceased-donor (formerly known as cadaveric) or living-donor transplant ...
, young children with significant vesicoureteral reflux, and those undergoing surgery of the
urinary tract The urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, c ...
. Bacteriuria without symptoms is present in about 3% of otherwise healthy middle aged women. In
nursing homes A nursing home is a facility for the residential care of elderly or disabled people. Nursing homes may also be referred to as skilled nursing facility (SNF) or long-term care facilities. Often, these terms have slightly different meanings to i ...
rates are as high as 50% among women and 40% in men. In those with a long term indwelling urinary catheter rates are 100%. Up to 10% of women have a urinary tract infection in a given year and half of all women have at least one infection at some point in their lives. There is an increased risk of asymptomatic or symptomatic bacteriuria in pregnancy due to physiological changes that occur in a pregnant women which promotes unwanted pathogen growth in the urinary tract.


Signs and symptoms


Asymptomatic

Asymptomatic bacteriuria is bacteriuria without accompanying symptoms of a urinary tract infection and is commonly caused by the bacterium ''Escherichia coli''. Other potential pathogens are ''Klebsiella spp''., and group B streptococci. It is more common in women, in the elderly, in residents of long-term care facilities, and in people with diabetes, bladder catheters, and spinal cord injuries. People with a long-term Foley catheter always show bacteriuria. Chronic asymptomatic bacteriuria occurs in as many as 50% of the population in long-term care. There is an association between asymptomatic bacteriuria in pregnant women with low birth weight, preterm delivery, cystitis, infection of the newborn and fetus death. However, most of these studies were graded as poor quality. Bacteriuria in pregnancy also increases the risk of
preeclampsia Pre-eclampsia is a disorder of pregnancy characterized by the onset of high blood pressure and often a significant amount of protein in the urine. When it arises, the condition begins after 20 weeks of pregnancy. In severe cases of the disease ...
.


Symptomatic

Symptomatic bacteriuria is bacteriuria with the accompanying symptoms of a
urinary tract infection A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidne ...
(such as frequent urination, painful urination, fever, back pain, abdominal pain and blood in the urine) and includes
pyelonephritis Pyelonephritis is inflammation of the kidney, typically due to a bacterial infection. Symptoms most often include fever and flank tenderness. Other symptoms may include nausea, burning with urination, and frequent urination. Complications ...
or
cystitis A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidney ...
. The most common cause of urinary tract infections is ''
Escherichia coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Esc ...
''.


Diagnosis

Testing for bacteriuria is usually performed in people with symptoms of a urinary tract infection. Certain populations that cannot feel or express symptoms of infection are also tested when showing nonspecific symptoms. For example, confusion or other changes in behaviour can be a sign of an infection in the elderly. Screening for asymptomatic bacteriuria in pregnancy is a common routine in many countries, but controversial. * The
gold standard A gold standard is a monetary system in which the standard economic unit of account is based on a fixed quantity of gold. The gold standard was the basis for the international monetary system from the 1870s to the early 1920s, and from th ...
for detecting bacteriuria is a bacterial culture which identifies the concentration of bacterial cells in the urine. The culture is usually combined with subsequent testing using biochemical methods or MALDI-TOF, which allows to identify the bacterial species, and antibiotic susceptibility testing. Urine culture is quantitative and very reliable, but can take at least one day to obtain a result and it is expensive.Miniaturization of bacterial culture within dipstick format, Digital Dipstick, allows bacterial detection, identification and quantification for bacteriuria within 10–12 hours at the
point-of-care Clinical point of care (POC) is the point in time when clinicians deliver healthcare products and services to patients at the time of care. Clinical documentation Clinical documentation is a record of the critical thinking and judgment of a heal ...
. Clinicians will often treat symptomatic bacteriuria based on the results of the urine dipstick test while waiting for the culture results. *Bacteriuria can usually be detected using a urine dipstick test. The
nitrite The nitrite ion has the chemical formula . Nitrite (mostly sodium nitrite) is widely used throughout chemical and pharmaceutical industries. The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name nitrite also ...
test detects nitrate-reducing bacteria if growing in high numbers in urine. A negative dipstick test does not exclude bacteriuria, as not all bacteria which can colonise the urinary tract are nitrate-reducing. The leukocyte esterase test indirectly detects the presence of leukocytes (
white blood cell White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from mult ...
s) in urine which can be associated with a urinary tract infection. In the elderly, the leukocyte esterase test is often positive even in the absence of an infection. The urine dipstick test is readily available and provides fast, but often unreliable results. * Microscopy can also be used to detect bacteriuria. It is rarely used in clinical routine since it requires more time and equipment and does not allow reliable identification or quantification of the causal bacterial species. Bacteriuria is assumed if a single bacterial species is isolated in a concentration greater than 100,000 colony forming units per millilitre of urine in clean-catch midstream urine specimens. In urine samples obtained from women, there is a risk for bacterial contamination from the vaginal flora. Therefore, in research, usually a second specimen is analysed to confirm asymptomatic bacteriuria in women. For urine collected via bladder catheterization in men and women, a single urine specimen with greater than 100,000 colony forming units of a single species per millilitre is considered diagnostic. The threshold for women displaying UTI symptoms can be as low as 100 colony forming units of a single species per millilitre. However, bacteria below a threshold of 10000 colony forming units per millilitre are usually reported as "no growth" by clinical laboratories. Using special techniques certain non-disease causing bacteria have also been found in the urine of healthy people. These are part of the resident microbiota.


Screening

Although controversial, many countries including the United States recommend a one time screening for bacteriuria during mid pregnancy. The screening method is by urine culture. Screening non-pregnant adults is recommended against by the United States Preventive Task Force.


Treatment

The decision to treat bacteriuria depends on the presence of accompanying symptoms and comorbidities.


Asymptomatic

Asymptomatic bacteriuria generally does not require treatment. Exceptions include those undergoing surgery of the urinary tract, children with vesicoureteral reflux or others with structural abnormalities of the urinary tract. In many countries, regional guidelines recommend treatment of pregnant women. There is no indication to treat asymptomatic bacteriuria in diabetics, renal transplant recipients, and in those with spinal cord injuries. The overuse of antibiotics to treat asymptomatic bacteriuria has many adverse effects such as an increased risk of diarrhea, the spread of
antimicrobial resistance Antimicrobial resistance (AMR) occurs when microbes evolve mechanisms that protect them from the effects of antimicrobials. All classes of microbes can evolve resistance. Fungi evolve antifungal resistance. Viruses evolve antiviral resistance. P ...
, and infection due to Clostridium difficile.


Symptomatic

Symptomatic bacteriuria is synonymous with
urinary tract infection A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidne ...
and typically treated with
antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and preventio ...
. Common choices include nitrofurantoin and
trimethoprim/sulfamethoxazole Trimethoprim/sulfamethoxazole, sold under the brand name Bactrim among others, is a fixed-dose combination antibiotic medication used to treat a variety of bacterial infections. It consists of one part trimethoprim to five parts sulfamethoxa ...
.


Epidemiology


References


External links

{{Clinical microbiology techniques Bacteria and humans Abnormal clinical and laboratory findings for urine Wikipedia medicine articles ready to translate nl:Bacteriurie