Question

The image shows a skin condition with a raised, well-defined, bright red rash on the upper limb. What is the most suitable antibiotic for this condition?

• A. Amoxycillin & Clavulinic acid
• B. Amikacin
• C. Norfloxacin
• D. Metronidazole

Hint:

Think about the causative organism of the bright red, sharply demarcated skin infection shown.

Answer 1

The Correct Option is A

Step 1: Identify the condition from the image.
The image shows erysipelas -- a superficial skin infection involving the upper dermis and superficial lymphatics, characterized by a raised, well-defined, tender, bright red rash with a sharp, distinct border. This is distinct from cellulitis, which involves deeper tissues and has poorly defined borders.

Step 2: Identify the causative organism.
Erysipelas is caused predominantly by Streptococcus pyogenes (Group A beta-haemolytic streptococcus). Other streptococcal groups (B, C, G) may occasionally be involved.

Step 3: Select the appropriate antibiotic.
Since the causative organism is Streptococcus pyogenes, penicillin-group antibiotics are the drug of choice. Amoxycillin-clavulanic acid (a beta-lactam combined with a beta-lactamase inhibitor) covers streptococci effectively and is the most appropriate choice among the given options.

Step 4: Eliminate other options.
- Amikacin: an aminoglycoside, primarily effective against gram-negative organisms, not appropriate for streptococcal infections.
- Norfloxacin: a fluoroquinolone, primarily used for urinary and gastrointestinal infections.
- Metronidazole: covers anaerobes and some protozoa; not effective against streptococci.