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Question

Difficulty: MediumInfectious Diseases

Match each clinical exposure scenario with the most appropriate first-line oral antimicrobial regimen.

  • A 24-year-old man sustains a deep puncture wound to his foot after stepping on a rusty nail through his rubber-soled athletic shoe.Oral ciprofloxacin
  • A 32-year-old woman is bitten on the hand by another person during a physical altercation, resulting in a clenched-fist injury.Oral amoxicillin-clavulanate
  • A 19-year-old man develops regional axillary lymphadenopathy two weeks after adopting a stray kitten that scratched his arm.Oral azithromycin
  • A 45-year-old woman develops an expanding erythematous skin lesion with central clearing after a hiking trip in a wooded area of Connecticut.Oral doxycycline

Answer

Puncture wound through rubber shoe matches with Oral ciprofloxacin. Human bite matches with Oral amoxicillin-clavulanate. Kitten scratch with lymphadenopathy matches with Oral azithromycin. Erythema migrans matches with Oral doxycycline.
Each specific exposure history carries a predictable risk for classic bacterial pathogens that dictate empiric therapy. Puncture wounds through sneakers risk Pseudomonas (requires a fluoroquinolone like ciprofloxacin). Human bites risk Eikenella and anaerobes (requires amoxicillin-clavulanate). Cat scratches risk Bartonella (requires a macrolide like azithromycin). Tick-borne early Lyme disease requires a tetracycline (doxycycline).

Step-by-Step Solution

1
Identify the likely pathogen for the puncture wound through a rubber shoe.
Pseudomonas aeruginosa.
Rubber soles provide a moist, warm environment conducive to Pseudomonas colonization, which is inoculated deep into the tissue during the puncture.
2
Identify the likely pathogens for the human clenched-fist injury.
Eikenella corrodens and mixed oral anaerobes.
Human saliva contains these characteristic organisms, which are introduced into the joint space or tendon sheath when a fist strikes a tooth.
3
Identify the likely pathogen for the kitten scratch followed by lymphadenopathy.
Bartonella henselae.
This is the classic presentation and history for cat scratch disease.
4
Identify the likely pathogen for the expanding rash after a tick exposure in Connecticut.
Borrelia burgdorferi.
The rash is erythema migrans, pathognomonic for early Lyme disease.
5
Select the appropriate targeted antimicrobial therapy for each identified pathogen.
Ciprofloxacin for Pseudomonas, amoxicillin-clavulanate for Eikenella and anaerobes, azithromycin for Bartonella, and doxycycline for Borrelia.
These specific agents represent the guideline-directed standard of care for these distinct environmental and zoonotic exposures.

Key Concept

Empiric antimicrobial selection based on specific environmental and zoonotic exposures.
Estimated Time:1m 30s
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Topics

Infectious Diseases

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