Bacteriuria

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

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, not containing bacteria. 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.

Bacteria can be detected with a dipstick test for nitrite or by urinary microscopy, 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 100000 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.

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.

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.[1][2] This has not been proven for older people or people with diabetes, bladder catheters or spinal cord injuries.[3] 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.[4] The presence of simultaneous pyuria does not warrant treatment by itself.

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[edit] Footnotes

  1. ^ Screening for Asymptomatic Bacteriuria. February 2004. U.S. Preventive Services Task Force. Agency for Healthcare Research and Quality, Rockville, MD.
  2. ^ Smaill F, Vazquez JC. Antibiotics for asymptomatic bacteriuria in pregnancy. Cochrane Database Syst Rev. 2007;(2):CD000490. PMID 17443502
  3. ^ Colgan R, Nicolle LE, McGlone A, Hooton TM. Asymptomatic bacteriuria in adults. Am Fam Physician. 2006;74(6):985-90. PMID 17002033
  4. ^ Asymptomatic bacteriuria from Medline Plus. Updated May 26, 2006, retrieved January 28, 2008.