Asymptomatic Bacteriuria: Clinical Pearls Blog

Gerard Kiernan, MD, FAAFP, FHMClinical Pearls, Family Medicine, Internal Medicine, Nurse Practitioner

Asymptomatic Bacteriuria positive urine culture

Asymptomatic Bacteriuria

Clinical Pearls of Wisdom Q&A Case

Asymptomatic bacteriuria (ASB) is a common finding in many populations, including healthy women and persons with underlying urologic abnormalities or those who have bladder catheters inserted for an extended period.  Asymptomatic bacteriuria is a condition in which larger than normal numbers of bacteria are present in the urine but symptoms do not result.

Asymptomatic Bacteriuria Case:

A 76-year-old woman with Alzheimer’s disease, hypertension, hyperlipidemia and coronary artery disease resides in a skilled nursing facility (SNF), in a memory-care unit. Two days ago, she was found on the floor, just outside the bathroom door. She was transported to the emergency department for evaluation.

There, she was confused, but afebrile.

  • Her blood pressure was 136/74 mm Hg, pulse was 86.
  • Her urinalysis showed 2+ leukocytes and urine was sent for culture.
  • Her white blood cell count was 9800/mm3 and her creatinine was 0.9 mg/dL.
  • A CT scan of the head and neck showed no evidence of trauma but did show cerebral atrophy and cervical spondylosis.
  • She did not complain of headache, neck pain, or dysuria and was sent back to SNF.

Now, you receive the results of her urine culture, which show 150,000 Colony Forming Units of E. coli.

You call the nursing home and find out that she remains confused, but that vital signs are normal.


What is the correct next step in response to this positive urine culture result?

Answer Options:

Treat with trimethoprim-sulfamethoxazole double-strength orally, twice a day, for five days.

Treat with nitrofurantoin 100mg orally twice daily for three days.

Do not initiate antimicrobial therapy.

Repeat urinalysis and culture if urinalysis is positive; consider treatment if second culture is positive.

See the Answer:

About the Author:

Gerard Kiernan, MD, FAAFP, FHM is a Dartmouth-Hitchcock Clinic hospitalist in Keene, NH. He attended the University of Rochester School of Medicine and Dentistry, followed by a Family Medicine residency at the University of Wisconsin, Madison, where he was a chief resident. Dr. Kiernan is a Lean Six Sigma Greenbelt and has led hospital medicine quality improvement efforts. He is a fellow of both the American Academy of Family Physicians and the Society of Hospital Medicine. He has achieved the Recognition of Focused Practice in Hospital Medicine offered through the AAFP and ABIM via their joint examination pathway.

About Clinical Pearl of the Month:

Med-Challenger's Clinical Pearl Blog Series is a recurring segment of Med-Challenger's popular Medical Education Blog. Med-Challenger provides online medical education products and services to physicians, nurses, and other medical specialists as well as medical training programs and healthcare groups world-wide via its web-based medical education library and world-class assessment platform at

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