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Zorluk: OrtaInfectious Diseases

A 42-year-old man presents to the clinic with a 2-day history of a progressively spreading red, swollen, and tender area on his right lower extremity. He recalls scratching a mosquito bite in the same location a few days prior. He has no significant past medical history and takes no medications. Vital signs are temperature 37.3°C (99.1°F), blood pressure 124/76 mmHg, pulse 82/min, and respirations 14/min. Physical examination reveals a 10-cm area of diffuse erythema, warmth, and induration on the right shin. The borders of the erythema are indistinct. There is no palpable fluctuance, purulent drainage, ulceration, or crepitus. Peripheral pulses and distal sensation are intact. Which of the following is the most appropriate empiric pharmacotherapy for this patient?

  1. Oral cephalexinCevap
  2. B
    Oral trimethoprim-sulfamethoxazole
  3. C
    Intravenous vancomycin
  4. D
    Oral ciprofloxacin
  5. E
    Topical mupirocin

Cevap

Oral cephalexin is the correct empiric pharmacotherapy for mild, non-purulent cellulitis.
Oral cephalexin is the correct choice because the patient presents with mild, non-purulent cellulitis. This condition is most frequently caused by beta-hemolytic streptococci (particularly Group A Streptococcus) and methicillin-susceptible Staphylococcus aureus (MSSA). Cephalexin is a first-generation cephalosporin that provides excellent oral coverage against these typical pathogens, making it the preferred first-line therapy for outpatient management.

Adım Adım Çözüm

1
Analyze the clinical presentation.
The patient has a localized, poorly demarcated area of erythema, warmth, and induration on the lower extremity without any fluctuance or purulence.
To classify the type of skin and soft tissue infection (SSTI) as purulent or non-purulent.
2
Identify the type of infection.
The presentation is classic for mild, non-purulent cellulitis.
Accurate classification is essential for guiding empiric antibiotic therapy.
3
Determine the most likely causative organisms.
The primary pathogens are beta-hemolytic streptococci (e.g., Group A Strep) and methicillin-susceptible Staphylococcus aureus (MSSA).
Antibiotic choice must provide targeted coverage for the most probable pathogens.
4
Select the best empiric pharmacotherapy.
Oral cephalexin is chosen as it provides excellent, narrow-spectrum coverage against both streptococci and MSSA.
It offers effective coverage suitable for mild outpatient cases while adhering to antibiotic stewardship principles.

Anahtar Kavram

Mild, non-purulent cellulitis is primarily caused by beta-hemolytic streptococci and MSSA, and should be treated empirically with an oral beta-lactam such as cephalexin or dicloxacillin. Coverage for MRSA (e.g., with trimethoprim-sulfamethoxazole) is reserved for purulent infections or those failing initial therapy.
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