Examkin

Question

Difficulty: MediumGeneral Internal Medicine

During morning rounds, a 64-year-old woman is evaluated on her third hospital day for management of acute pyelonephritis. She initially presented to the emergency department with a temperature of 38.9°C (102.0°F), right-sided flank pain, and persistent emesis. Blood and urine cultures were drawn, and empiric intravenous piperacillin-tazobactam was initiated.

Today, the patient reports feeling much better. Her flank pain has nearly resolved, and she is eating a regular diet without nausea. She has been afebrile for the past 24 hours. Current vital signs are temperature 37.1°C (98.8°F), heart rate 78/min, and blood pressure 118/76 mm Hg.

The admission blood and urine cultures are now finalizing, both demonstrating heavy growth of *Escherichia coli*. The isolate susceptibility report is as follows:

Antimicrobial AgentSusceptibility
AmpicillinResistant
CeftriaxoneSusceptible
CiprofloxacinSusceptible
FosfomycinSusceptible
Piperacillin-tazobactamSusceptible
Trimethoprim-sulfamethoxazoleSusceptible

The patient has no known drug allergies. Her serum creatinine is 0.80.8 mg/dL.

Which of the following is the most appropriate next step in pharmacologic management?

  1. Transition to oral trimethoprim-sulfamethoxazoleAnswer
  2. B
    Transition to oral ciprofloxacin
  3. C
    Transition to oral fosfomycin
  4. D
    Continue intravenous piperacillin-tazobactam
  5. E
    Transition to intravenous ceftriaxone

Answer

Transition to oral trimethoprim-sulfamethoxazole
The correct decision is to transition the patient to oral trimethoprim-sulfamethoxazole. This patient was admitted with bacteremic acute pyelonephritis and has rapidly improved on empiric intravenous therapy. Because she has been afebrile for at least 24 hours, is hemodynamically stable, and is tolerating an oral diet, she is an excellent candidate for step-down to oral antibiotics. The goal of antimicrobial stewardship is to utilize the narrowest effective agent with appropriate pharmacokinetics for the site of infection. Trimethoprim-sulfamethoxazole has excellent oral bioavailability and achieves high concentrations in both the serum and renal parenchyma. This choice safely facilitates hospital discharge while avoiding unnecessarily broad antibiotics.

Step-by-Step Solution

1
Assess the patient's clinical trajectory to determine eligibility for intravenous to oral transition.
The patient is afebrile for 24 hours, hemodynamically stable, and tolerating a regular diet.
Meeting these criteria indicates the patient can safely absorb and respond to oral antimicrobial therapy.
2
Evaluate the susceptibility report to identify viable oral step-down options.
The isolate is susceptible to ciprofloxacin, fosfomycin, and trimethoprim-sulfamethoxazole.
Oral step-down requires an agent that is active against the specific pathogen isolated.
3
Select the most appropriate oral agent based on pharmacokinetics and antimicrobial stewardship.
Trimethoprim-sulfamethoxazole is selected.
Fosfomycin lacks adequate renal tissue penetration for pyelonephritis. Ciprofloxacin is excessively broad and carries severe side effect warnings. Trimethoprim-sulfamethoxazole provides excellent tissue penetration with a narrower spectrum.

Key Concept

Antimicrobial stewardship in transitioning from intravenous to oral therapy for complicated urinary tract infections.
Estimated Time:1m 15s
Rate this question

Topics

General Internal Medicine

More questions from this topic