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Difficulty: HardInfectious Diseases

A 74-year-old woman is evaluated in the outpatient clinic for medical clearance 3 days prior to an elective right total hip arthroplasty. Her medical history includes well-controlled type 2 diabetes mellitus, essential hypertension, and osteoarthritis. She reports feeling well and explicitly denies fever, chills, flank pain, dysuria, or increased urinary frequency. Vital signs show a temperature of 37.1°C (98.8°F), blood pressure of 128/78 mmHg, and a pulse of 76/min. Physical examination is unremarkable with no costovertebral angle tenderness or suprapubic pain. As part of a preoperative protocol mandated by the surgical center, a urinalysis and urine culture are obtained. The urinalysis reveals a specific gravity of 1.018, pH of 6.5, positive leukocyte esterase, positive nitrites, and 45 white blood cells per high-power field. Two days later, the urine culture grows >105>10^5 CFU/mL of *Klebsiella pneumoniae*. Antimicrobial susceptibility testing indicates the isolate is susceptible to cephalexin, ciprofloxacin, and trimethoprim-sulfamethoxazole. Which of the following is the most appropriate management regarding the patient's urinary findings?

  1. Proceed with the scheduled surgery without prescribing antimicrobial therapy for the urinary findingsAnswer
  2. B
    Prescribe a short course of oral cephalexin to be completed prior to the surgical procedure
  3. C
    Prescribe oral ciprofloxacin to eradicate the organism and prevent prosthetic seeding
  4. D
    Recommend broadening the perioperative intravenous antibiotic prophylaxis to target the isolated organism
  5. E
    Postpone the arthroplasty until a repeat urine culture demonstrates clearance of the bacteriuria

Answer

Proceed with the scheduled surgery without prescribing antimicrobial therapy for the urinary findings
The correct approach is to proceed with the scheduled surgery without antimicrobial therapy. This patient has asymptomatic bacteriuria (ASB), which is defined as the presence of bacteria in the urine in the absence of signs or symptoms of a urinary tract infection (UTI). Crucially, the presence of pyuria (white blood cells) or a positive leukocyte esterase on urinalysis is highly prevalent in ASB and does not differentiate it from a true symptomatic UTI. Clinical guidelines strictly recommend against screening for or treating ASB, with two major exceptions: pregnant patients and patients undergoing urologic procedures where mucosal trauma is anticipated. For all other patients, including the elderly, patients with diabetes, and those undergoing non-urologic surgery such as total joint arthroplasty, treating ASB provides no benefit and does not reduce the risk of surgical site infections or prosthetic joint infections. Instead, treating ASB violates antibiotic stewardship principles by needlessly exposing patients to medication side effects, increasing the risk of Clostridioides difficile infection, and promoting antimicrobial resistance.

Step-by-Step Solution

1
Analyze the clinical presentation and laboratory findings.
The patient has significant bacteriuria and pyuria (>10^5 CFU/mL Klebsiella, 45 WBCs/hpf) but is completely devoid of systemic or localized urinary symptoms.
Correlating objective laboratory data with clinical symptoms is necessary to differentiate true infection from colonization.
2
Establish the correct diagnosis for the urinary findings.
The diagnosis is asymptomatic bacteriuria (ASB).
ASB is defined by a positive urine culture in a patient without urinary symptoms. The presence of pyuria (white blood cells) does not alter this diagnosis and should not be used to justify antibiotic therapy.
3
Apply infectious disease guidelines for the treatment of ASB.
Treatment of ASB is indicated ONLY in pregnant patients and those undergoing urologic procedures with anticipated mucosal trauma.
Treating ASB outside of these specific indications provides no clinical benefit and increases the risk of adverse drug events and antimicrobial resistance.
4
Determine the next best step for a patient undergoing orthopedic surgery.
No intervention for the bacteriuria is required; proceed with the surgery.
Orthopedic surgery (such as hip arthroplasty) is a non-urologic procedure. Treating ASB does not decrease the rate of prosthetic joint infection.

Key Concept

Asymptomatic bacteriuria requires no treatment prior to non-urologic procedures, including orthopedic arthroplasty, even in the presence of pyuria.
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Topics

Infectious Diseases

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