Bacteriuria
Encyclopedia
In medicine
, bacteriuria denotes the presence of bacteria
in urine
not due to contamination from urine sample collection.
Urine is normally a sterile bodily fluid when inside the bladder, but can pick up commensals and pathogens when exiting through the urethra. Bacteria in the urine, especially gram-negative
rods, usually indicate a urinary tract infection
(either cystitis
or pyelonephritis
), although bacteriuria can also occur in prostatitis
. Escherichia coli
is the most common bacterium isolated from urine samples.
Asymptomatic bacteriuria is bacteriuria without accompanying symptoms of a urinary tract infection (such as frequent urination
, painful urination
or fever
). It is more common in women, in the elderly, in residents of long-term care facilities, and in patients with diabetes, bladder catheters and spinal cord injuries. Patients with a long-term Foley catheter
uniformly show bacteriuria.
, although bacterial culture remains the most specific and formal test (the golden standard
). Bacteriuria can be confirmed 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 (one for men, two consecutive specimens with the same bacterium for women). For urine collected via bladder catheterisation, the threshold is 100 colony forming units of a single species per millilitre.
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
, bacteriuria denotes the presence of bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
in urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...
not due to contamination from urine sample collection.
Urine is normally a sterile bodily fluid when inside the bladder, but can pick up commensals and pathogens when exiting through the urethra. Bacteria in the urine, especially gram-negative
Gram-negative
Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...
rods, usually indicate a urinary tract infection
Urinary tract infection
A urinary tract infection is a bacterial infection that affects any part of the urinary tract. Symptoms include frequent feeling and/or need to urinate, pain during urination, and cloudy urine. The main causal agent is Escherichia coli...
(either cystitis
Cystitis
Cystitis is a term that refers to urinary bladder inflammation that results from any one of a number of distinct syndromes. It is most commonly caused by a bacterial infection in which case it is referred to as a urinary tract infection.-Signs and symptoms:...
or pyelonephritis
Pyelonephritis
Pyelonephritis is an ascending urinary tract infection that has reached the pyelum or pelvis of the kidney. It is a form of nephritis that is also referred to as pyelitis...
), although bacteriuria can also occur in prostatitis
Prostatitis
Prostatitis is an inflammation of the prostate gland, in men. A prostatitis diagnosis is assigned at 8% of all urologist and 1% of all primary care physician visits in the United States.-Classification:...
. Escherichia coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
is the most common bacterium isolated from urine samples.
Asymptomatic bacteriuria is bacteriuria without accompanying symptoms of a urinary tract infection (such as frequent urination
Polyuria
Polyuria is a condition usually defined as excessive or abnormally large production or passage of urine . Frequent urination is sometimes included by definition, but is nonetheless usually an accompanying symptom...
, painful urination
Dysuria
In medicine, specifically urology, dysuria refers to painful urination.Difficult urination is also sometimes described as dysuria.It is one of a constellation of irritative bladder symptoms, which includes urinary frequency and haematuria....
or fever
Fever
Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
). It is more common in women, in the elderly, in residents of long-term care facilities, and in patients with diabetes, bladder catheters and spinal cord injuries. Patients with a long-term Foley catheter
Foley catheter
A Foley catheter is a flexible tube that is often passed through the urethra and into the bladder. The tube has two separated channels, or lumens, running down its length. One lumen is open at both ends, and allows urine to drain out into a collection bag...
uniformly show bacteriuria.
| Group | Prevalence (in %) | |
|---|---|---|
| Healthy premenopausal women | 1.0 to 5.0 | |
| Pregnant women | 1.9 to 9.5 | |
| Postmenopausal women (50 to 70 years of age) | 2.8 to 8.6 | |
| Patients with diabetes mellitus Diabetes mellitus Diabetes mellitus, often simply referred to as diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced... |
Women | 9.0 to 27.0 |
| Men | 0.7 to 1.0 | |
| Older community-dwelling patients | Women (older than 70 years) |
> 15.0 |
| Men | 3.6 to 19.0 | |
| Older long-term care Long-term care Long-term care is a variety of services which help meet both the medical and non-medical need of people with a chronic illness or disability who cannot care for themselves for long periods of time.... residents |
Women | 25.0 to 50.0 |
| Men | 15.0 to 40.0 | |
| Patients with spinal cord injury Spinal cord injury A spinal cord injury refers to any injury to the spinal cord that is caused by trauma instead of disease. Depending on where the spinal cord and nerve roots are damaged, the symptoms can vary widely, from pain to paralysis to incontinence... |
Intermittent catheter | 23.0 to 89.0 |
| Sphincterotomy and condom catheter |
57.0 | |
| Patients undergoing hemodialysis Hemodialysis In medicine, hemodialysis is a method for removing waste products such as creatinine and urea, as well as free water from the blood when the kidneys are in renal failure. Hemodialysis is one of three renal replacement therapies .Hemodialysis can be an outpatient or inpatient therapy... |
28.0 | |
| Patients with an indwelling catheter | Short-term | 9.0 to 23.0 |
| Long-term | 100 | |
Diagnosis
Bacteria can be detected with a urine dipstick test for urinary nitrite or by urinary microscopyMicroscopy
Microscopy is the technical field of using microscopes to view samples and objects that cannot be seen with the unaided eye...
, although bacterial culture remains the most specific and formal test (the golden standard
Gold standard (test)
In medicine and statistics, gold standard test refers to a diagnostic test or benchmark that is the best available under reasonable conditions. It does not have to be necessarily the best possible test for the condition in absolute terms...
). Bacteriuria can be confirmed 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 (one for men, two consecutive specimens with the same bacterium for women). For urine collected via bladder catheterisation, the threshold is 100 colony forming units of a single species per millilitre.
Treatment
The presence of simultaneous pyuria does not warrant treatment by itself.- Screening for asymptomatic bacteriuria with urine culture and treatment with antibiotics is recommended during pregnancyPregnancyPregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
, because it significantly reduces symptomatic urinary tract infections, low birth weightLow birth weightLow birth weight is defined as a birth weight of a liveborn infant of less than 2,500 g. regardless of gestational age-Causes:LBW is either the result of preterm birth or of the infant being small for gestational age , or a combination of...
, and preterm delivery.
- This has not been proven for older people or people with diabetes, bladder catheters or spinal cord injuries.
- Kidney transplant recipients, children with vesicoureteral refluxVesicoureteral refluxVesicoureteral reflux is an abnormal movement of urine from the bladder into ureters or kidneys. Urine normally travels from the kidneys via the ureters to the bladder...
or others with structural abnormalities of the urinary tract, people with infected kidney stones and those who are having urological procedures might be more likely to benefit from treatment with antibiotics for asymptomatic bacteriuria.