Infection · Easy
This case is fictional and exists for study. It describes no real patient.
68 years · female
A 68-year-old woman attends a general practice clinic for a routine hypertension review. She reports feeling entirely well with no urinary symptoms such as dysuria, urgency, frequency, or suprapubic discomfort. She has no fever, chills, or flank pain. As part of a routine health check prior to her visit, a midstream urine sample was collected and sent by a practice nurse. The laboratory reports growth of >10^5 CFU/mL Escherichia coli, sensitive to nitrofurantoin, trimethoprim, and amoxicillin. On physical examination, her abdomen is soft and non-tender, with no suprapubic or costovertebral angle tenderness.
Vital signs
- HR
- 72 bpm
- BP
- 128/82 mmHg
- RR
- 14/min
- Temp
- 36.6 °C
- SpO₂
- 98%
Examination findings
- Abdomen soft and non-tender
- No suprapubic tenderness
- No costovertebral angle tenderness
Investigations
| White Blood Cell Count | 6.5 10^9/L | reference: 4.0-11.0 |
| C-Reactive Protein | 2 mg/L | reference: 0-5 |
| Midstream Urine Culture | >10^5 Escherichia coli CFU/mL | reference: <10^3 |
Question 1 of 3
Which of the following is the single most appropriate management action for this patient?
Option B is correct because the patient has asymptomatic bacteriuria (ASB). Principles of antibiotic stewardship mandate that ASB should not be treated in non-pregnant, non-urological surgery patients, as antimicrobial therapy confers no clinical benefit and increases the risk of side effects and bacterial resistance. Options A and C are incorrect because initiating antibiotics is inappropriate without symptoms. Option D is incorrect because routine repeat cultures in asymptomatic non-pregnant individuals are unnecessary and discourage good stewardship.
Teaching point: Asymptomatic bacteriuria in non-pregnant, non-urological surgery patients should not be treated with antibiotics.
Question 2 of 3
What is the most likely diagnosis?
Option C is correct. Asymptomatic bacteriuria is defined as significant bacterial growth (>10^5 CFU/mL) in the urine of a patient without urinary symptoms. Option B is incorrect because cystitis requires localized symptoms such as dysuria, frequency, or urgency. Option A is incorrect because pyelonephritis involves systemic features like fever, rigors, or flank pain. Option D is incorrect because >10^5 CFU/mL of a single organism represents bacterial colonization rather than simple skin flora contamination.
Teaching point: Significant bacteriuria (>10^5 CFU/mL) without urinary symptoms defines asymptomatic bacteriuria.
Question 3 of 3
In which of the following clinical scenarios would screening and antibiotic treatment for asymptomatic bacteriuria be indicated?
Pregnancy is the answer. Pregnant women must be screened and treated for asymptomatic bacteriuria, because untreated ASB raises the risk of acute pyelonephritis, low birth weight and preterm labour. The other three — a long-term indwelling urinary catheter, well-controlled type 2 diabetes, and residence in long-term care — are exactly the settings in which asymptomatic bacteriuria should NOT be screened for or treated: bacteriuria is expected there, treating it does not help, and it drives antibiotic resistance and Clostridioides difficile.
Teaching point: Pregnancy and planned invasive urological procedures are key indications to screen for and treat asymptomatic bacteriuria.
Key learning points
- Asymptomatic bacteriuria is common in older adults and should not be treated with antibiotics unless specific indications exist.
- Unnecessary antibiotic treatment of asymptomatic bacteriuria increases antibiotic resistance, drug side effects, and risk of Clostridioides difficile infection.
- Pregnancy and planned endourological procedures involving mucosal trauma are major indications for screening and treating asymptomatic bacteriuria.
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