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Difficulty: MediumInfectious Diseases

A 71-year-old female presents to the orthopedic clinic for a final preoperative evaluation. She is scheduled to undergo an elective right total knee arthroplasty in one week for severe osteoarthritis. Her medical history includes hypertension and diet-controlled type 2 diabetes mellitus. The patient feels well and reports no dysuria, urinary frequency, urgency, or suprapubic discomfort. Vital signs are within normal limits. Physical examination reveals crepitus and decreased range of motion in the right knee but is otherwise unremarkable. Routine preoperative laboratory testing is notable for a urinalysis demonstrating positive leukocyte esterase and 15 leukocytes/hpf. A reflex urine culture grows >105>10^{5} CFU/mL of *Escherichia coli* that is susceptible to cephalexin, nitrofurantoin, ciprofloxacin, and trimethoprim-sulfamethoxazole. Which of the following is the most appropriate management regarding her urinary findings?

  1. A
    Prescribe a 3-day course of oral ciprofloxacin
  2. B
    Prescribe a 5-day course of oral nitrofurantoin
  3. C
    Delay the surgery until a repeat urine culture is sterile
  4. Proceed with surgery without targeted antimicrobial therapy for the bacteriuriaAnswer
  5. E
    Administer a single dose of intravenous gentamicin immediately prior to the incision

Answer

Proceed with surgery without targeted antimicrobial therapy for the bacteriuria.
The correct management is to proceed with surgery without targeted antimicrobial therapy. This patient has asymptomatic bacteriuria (ASB), which is defined as bacterial growth ≥105\geq 10^{5} CFU/mL in a patient without signs or symptoms of a urinary tract infection. According to current Infectious Diseases Society of America (IDSA) guidelines, screening for and treating ASB is NOT indicated prior to non-urologic surgeries, including total joint arthroplasties. Treatment of ASB in this setting does not reduce the incidence of prosthetic joint infections but significantly increases the risk of adverse antimicrobial effects, promotes the development of multidrug-resistant organisms, and violates core principles of antimicrobial stewardship.

Step-by-Step Solution

1
Evaluate the patient's clinical presentation.
The patient is an asymptomatic 71-year-old female preparing for a knee arthroplasty.
To distinguish between symptomatic urinary tract infection and asymptomatic bacteriuria.
2
Analyze the urinalysis and culture results.
Positive leukocyte esterase and growth of >105>10^{5} CFU/mL E. coli without accompanying urinary symptoms.
To formally confirm the diagnosis of asymptomatic bacteriuria.
3
Determine the indication for antibiotic therapy based on the planned procedure.
The patient is undergoing a non-urologic procedure (total knee arthroplasty).
Current guidelines recommend against treating asymptomatic bacteriuria prior to non-urologic surgery.

Key Concept

Asymptomatic bacteriuria should not be screened for or treated prior to non-urologic surgical procedures, including orthopedic joint replacements.
Estimated Time:1m 15s
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Topics

Infectious Diseases

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