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Bacteriuria pyuria 4.jpg
Multiple rod-shaped bacteria shown between the larger white blood cells at urinary microscopy from a patient with urinary tract infection.
Classification and external resources
MedlinePlus 000520

Bacteriuria means the presence of bacteria in urine but not if the bacteria's presence is due to contamination during urine sample collection. Bacteria in the urine, especially gram-negative rods, often 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 people with diabetes, bladder catheters and spinal cord injuries. People with a long-term Foley catheter uniformly show bacteriuria.

Chronic asymptomatic bacteriuria without urinary tract infection symptoms occurs in as many as 50% of the population in long-term care.[1]

Rates of asymptomatic bacteriuria[2]
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
People with diabetes mellitus Women 9.0 to 27.0
Men 0.7 to 1.0
Older community-dwelling people 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
People with spinal cord injury Intermittent catheter 23.0 to 89.0
Sphincterotomy and
condom catheter
People undergoing hemodialysis 28.0
People 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).

Per Infectious Disease Society of America guidelines, 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).[3] 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.[3] The threshold is also 100 colony forming units of a single species per millilitre for women displaying UTI symptoms.[4]


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 there is some evidence that it reduces symptomatic urinary tract infections, low birth weight, and preterm delivery.[5][6] A typical course of antibiotics is recommended.[7]
  • Treatment is recommended for asymptomatic bacteriuria in patients undergoing invasive urological procedure
  • This has not been proven for older people or people with diabetes, bladder catheters or spinal cord injuries.[8][9]
  • 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.[10]
  • The overuse of antibiotic therapy to treat asymptomatic bacteriuria leads to an increased risk of diarrhea, resistant organisms and infection due to Clostridium difficile.[1]


  1. ^ a b AMDA – The Society for Post-Acute and Long-Term Care Medicine (February 2014), "Ten Things Physicians and Patients Should Question", Choosing Wisely: an initiative of the ABIM Foundation, AMDA – The Society for Post-Acute and Long-Term Care Medicine, retrieved 20 April 2015 
  2. ^ [1] Colgan, R.; Nicolle, L. E.; McGlone, A.; Hooton, T. M. (2006). "Asymptomatic bacteriuria in adults". American family physician. 74 (6): 985–990. PMID 17002033. 
  3. ^ a b Detweiler K, Mayers D, Fletcher SG (November 2015). "Bacteruria and Urinary Tract Infections in the Elderly". The Urologic Clinics of North America (Review). 42 (4): 561–8. PMID 26475952. doi:10.1016/j.ucl.2015.07.002. 
  4. ^ Sam, Amir H.; James T.H. Teo (2010). Rapid Medicine. Wiley-Blackwell. ISBN 1-4051-8323-3. 
  5. ^ 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. PMID 18591632. doi:10.7326/0003-4819-149-1-200807010-00009-w1. 
  6. ^ Smaill, FM; Vazquez, JC (7 August 2015). "Antibiotics for asymptomatic bacteriuria in pregnancy". The Cochrane database of systematic reviews (8): CD000490. PMID 26252501. doi:10.1002/14651858.CD000490.pub3. 
  7. ^ Widmer, M; Lopez, I; Gülmezoglu, AM; Mignini, L; Roganti, A (11 November 2015). "Duration of treatment for asymptomatic bacteriuria during pregnancy". The Cochrane database of systematic reviews (11): CD000491. PMID 26560337. doi:10.1002/14651858.CD000491.pub3. 
  8. ^ Colgan R, Nicolle LE, McGlone A, Hooton TM (2006). "Asymptomatic bacteriuria in adults". Am Fam Physician. 74 (6): 985–90. PMID 17002033. 
  9. ^ For information about older people only, American Geriatrics Society, "Five Things Physicians and Patients Should Question", Choosing Wisely: an initiative of the ABIM Foundation, American Geriatrics Society, retrieved August 1, 2013 , 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. PMID 3960089. doi:10.1056/NEJM198605013141804. 
    • 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. PMID 3300325. doi:10.1016/0002-9343(87)90493-1. 
    • Juthani-Mehta, M. (2007). "Asymptomatic Bacteriuria and Urinary Tract Infection in Older Adults". Clinics in Geriatric Medicine. 23 (3): 585–594, vii. PMID 17631235. doi:10.1016/j.cger.2007.03.001. 
    • 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. PMID 15714408. doi:10.1086/427507. 
  10. ^ Asymptomatic bacteriuria from Medline Plus. Updated May 26, 2006, retrieved January 28, 2008.