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Zorluk: OrtaInfectious Diseases

A 47-year-old woman with a history of type 2 diabetes mellitus is evaluated on hospital day 4 for ongoing management of a left foot infection. She initially presented to the emergency department with a deep, purulent ulcer on the plantar surface of her foot, surrounded by a 6-cm area of erythema and induration. On admission, she was febrile and had leukocytosis. She was started on empiric intravenous vancomycin and piperacillin-tazobactam and underwent prompt surgical debridement. The surgeon noted no evidence of bone involvement, which was confirmed by a negative MRI of the foot. Today, her temperature is 37.0°C (98.6°F), blood pressure is 122/78 mm Hg, and pulse is 76/min. The surgical wound is clean with healthy granulation tissue, and the surrounding erythema has nearly resolved. Intraoperative deep tissue cultures now show heavy growth of methicillin-susceptible Staphylococcus aureus (MSSA) and Streptococcus agalactiae. Susceptibility testing indicates both isolates are susceptible to cefazolin, cephalexin, and ampicillin. The MSSA isolate is resistant to clindamycin. Which of the following is the most appropriate next step in pharmacotherapy?

  1. Transition to oral cephalexinCevap
  2. B
    Continue intravenous vancomycin and piperacillin-tazobactam
  3. C
    Transition to intravenous vancomycin and discontinue piperacillin-tazobactam
  4. D
    Transition to oral ciprofloxacin and clindamycin
  5. E
    Transition to oral trimethoprim-sulfamethoxazole

Cevap

Transition to oral cephalexin
The correct answer is to transition to oral cephalexin. The patient has a resolving diabetic foot infection (soft tissue only) with confirmed methicillin-susceptible Staphylococcus aureus (MSSA) and Streptococcus agalactiae (Group B Streptococcus). Since she is clinically stable, afebrile, and the wound is improving following surgical debridement, she is an excellent candidate for transitioning from intravenous to oral antimicrobial therapy. A core principle of antimicrobial stewardship is to de-escalate broad-spectrum empiric therapy to targeted, narrow-spectrum agents once culture and susceptibility data are available. Both isolated organisms are highly susceptible to first-generation cephalosporins. Oral cephalexin provides excellent, targeted coverage for both MSSA and beta-hemolytic streptococci, making it the most appropriate and effective choice to complete her treatment course.

Adım Adım Çözüm

1
Evaluate the patient's clinical stability and source control.
The patient is afebrile, her wound is improving post-debridement, and bone involvement has been ruled out.
Clinical stability indicates the patient is ready to transition from intravenous to oral antibiotics for discharge planning.
2
Analyze the deep tissue culture and susceptibility results.
Cultures grew methicillin-susceptible Staphylococcus aureus (MSSA) and Streptococcus agalactiae, both sensitive to first-generation cephalosporins.
Empiric broad-spectrum therapy must be de-escalated to target the specific isolated pathogens.
3
Select the most appropriate targeted antimicrobial agent.
Oral cephalexin is selected.
Cephalexin provides excellent, narrow-spectrum coverage for both MSSA and Group B Streptococcus, adhering to antimicrobial stewardship principles without using unnecessarily broad agents.

Anahtar Kavram

Antibiotic de-escalation to targeted beta-lactam therapy for methicillin-susceptible Staphylococcus aureus (MSSA) and beta-hemolytic streptococcal infections.
Tahmini Süre:1m 15s
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Infectious Diseases

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