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Difficulty: HardInfectious Diseases

During a preoperative assessment, a 74-year-old male is reviewed by the surgical team three days before an elective left total hip arthroplasty. He has longstanding osteoarthritis, diet-controlled type 2 diabetes mellitus, and mild benign prostatic hyperplasia. The patient feels well and explicitly denies any current urinary urgency, dysuria, increased frequency, or flank discomfort. His temperature is 37.0°C (98.6°F), blood pressure is 132/84 mmHg, and heart rate is 76/min. Aside from left hip stiffness and an antalgic gait, the physical examination is unremarkable.

Laboratory investigations are obtained as part of standard preoperative protocols. A midstream urine sample shows 18 leukocytes/hpf, positive leukocyte esterase, and negative nitrites. A reflex urine culture subsequently isolates >105>10^5 CFU/mL of Extended-Spectrum Beta-Lactamase (ESBL)-producing *Escherichia coli*. The isolate is resistant to ceftriaxone, ciprofloxacin, and trimethoprim-sulfamethoxazole, but retains susceptibility to meropenem, nitrofurantoin, and fosfomycin.

Based on these findings, which of the following is the most appropriate next step in the management of this patient's urinary findings?

  1. Proceed with the scheduled surgery without targeted urinary antimicrobial therapyAnswer
  2. B
    Prescribe a preoperative course of oral fosfomycin
  3. C
    Prescribe a preoperative course of oral nitrofurantoin
  4. D
    Administer intravenous meropenem during perioperative surgical prophylaxis
  5. E
    Delay the arthroplasty until a repeat urine culture is sterile

Answer

The most appropriate action is to proceed with the scheduled surgery without targeted urinary antimicrobial therapy.
The correct course of action is to proceed with the scheduled hip arthroplasty without prescribing targeted antibiotics for the urine. This patient's presentation meets the criteria for asymptomatic bacteriuria (ASB): bacterial growth of >105>10^5 CFU/mL in the absence of localized or systemic symptoms of a urinary tract infection. The Infectious Diseases Society of America (IDSA) explicitly recommends against screening for or treating ASB in patients undergoing non-urologic surgeries, including orthopedic joint replacements. Numerous large cohort studies have demonstrated that preoperative ASB is not a significant risk factor for prosthetic joint infection, and eradicating the bacteriuria prior to surgery does not improve surgical outcomes. While the presence of an ESBL-producing organism might seem alarming, treating colonization only exposes the patient to adverse drug effects, increases the risk of *Clostridioides difficile* infection, and promotes further antimicrobial resistance. Pyuria frequently accompanies ASB in older adults and is not an independent indication for treatment.

Step-by-Step Solution

1
Analyze the patient's clinical presentation and laboratory results.
The patient has >105>10^5 CFU/mL of ESBL-producing E. coli and pyuria, but entirely lacks signs or symptoms of a urinary tract infection (no dysuria, urgency, or fever).
Differentiating between asymptomatic bacteriuria (ASB) and a symptomatic UTI is the foundational step in urinary diagnostics.
2
Determine the significance of pyuria in this context.
Pyuria (18 leukocytes/hpf) is recognized as a common accompanying finding in ASB, particularly in the elderly, and does not alter the diagnosis.
Many clinicians erroneously believe pyuria mandates treatment; it is an expected inflammatory response to colonization.
3
Apply current treatment guidelines for ASB in the setting of upcoming surgery.
Guidelines strictly advise against treating ASB prior to non-urologic surgeries, including orthopedic joint replacements.
Treatment does not reduce the risk of prosthetic joint infections and unnecessarily drives antibiotic resistance.

Key Concept

Asymptomatic bacteriuria (ASB) does not require treatment prior to non-urologic surgeries, such as orthopedic joint arthroplasty, regardless of the organism's antimicrobial resistance profile or the presence of pyuria.
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Infectious Diseases

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