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Title: Bacteriuria  
Author: World Heritage Encyclopedia
Language: English
Subject: Bacteria, Sickle cell trait, Urinary tract infection, Proteinuria, Preterm birth
Collection: Abnormal Clinical and Laboratory Findings for Urine, Bacteria
Publisher: World Heritage Encyclopedia


Classification and external resources
Multiple rod-shaped bacteria shown between the larger white blood cells at urinary microscopy from a patient with urinary tract infection.
MedlinePlus 000520

In medicine, bacteriuria denotes the presence of bacteria in urine (but not if the bacteria's presence is due to contamination from urine sample collection.)


  • Overview 1
  • Diagnosis 2
  • Treatment 3
  • See also 4
  • References 5


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.

Prevalences of asymptomatic bacteriuria[1]
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 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 residents Women 25.0 to 50.0
Men 15.0 to 40.0
Patients with spinal cord injury Intermittent catheter 23.0 to 89.0
Sphincterotomy and
condom catheter
Patients undergoing hemodialysis 28.0
Patients with an indwelling
urinary catheter
Short-term 9.0 to 23.0
Long-term 100


Bacteria can be detected with a urine dipstick test for urinary nitrite or by urinary microscopy, although bacterial culture remains the most specific and formal test (the gold 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. The threshold is also 100 colony forming units of a single species per millilitre for women displaying UTI symptoms.[2]


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 pregnancy, because it significantly reduces symptomatic urinary tract infections, low birth weight, and preterm delivery.[3][4]
  • Kidney transplant recipients, children with vesicoureteral reflux 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.[7]

See also


  1. ^ [1] Colgan, R.; Nicolle, L. E.; McGlone, A.; Hooton, T. M. (2006). "Asymptomatic bacteriuria in adults". American family physician 74 (6): 985–990.  
  2. ^ Sam, Amir H.; James T.H. Teo (2010).  
  3. ^ Lin K, Fajardo K (July 2008). "Screening for asymptomatic bacteriuria in adults: evidence for the U.S. Preventive Services Task Force reaffirmation recommendation statement". Ann. Intern. Med. 149 (1): W20–4.  
  4. ^ Smaill F, Vazquez JC. Antibiotics for asymptomatic bacteriuria in pregnancy. Cochrane Database Syst Rev. 2007;(2):CD000490. PMID 17443502
  5. ^ Colgan R, Nicolle LE, McGlone A, Hooton TM. Asymptomatic bacteriuria in adults. Am Fam Physician. 2006;74(6):985-90. PMID 17002033
  6. ^ For information about older people only,  , which cites
    • Nordenstam, G. R.; Brandberg, C. Å.; Odén, A. S.; Svanborg Edén, C. M.; Svanborg, A. (1986). "Bacteriuria and Mortality in an Elderly Population". New England Journal of Medicine 314 (18): 1152–1156.  
    • Nicolle, L. E.; Mayhew, W. J.; Bryan, L. (1987). "Prospective randomized comparison of therapy and no therapy for asymptomatic bacteriuria in institutionalized elderly women". The American journal of medicine 83 (1): 27–33.  
    • Juthani-Mehta, M. (2007). "Asymptomatic Bacteriuria and Urinary Tract Infection in Older Adults". Clinics in Geriatric Medicine 23 (3): 585–594, vii.  
    • Nicolle, L. E.; Bradley, S.; Colgan, R.; Rice, J. C.; Schaeffer, A.; Hooton, T. M. (2005). "Infectious Diseases Society of America Guidelines for the Diagnosis and Treatment of Asymptomatic Bacteriuria in Adults". Clinical Infectious Diseases 40 (5): 643–654.  
  7. ^ Asymptomatic bacteriuria from Medline Plus. Updated May 26, 2006, retrieved January 28, 2008.
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