In the treatment of extensive impetigo, which oral antibiotic is commonly prescribed?

In the treatment of extensive impetigo, cephalexin is commonly prescribed because it is effective against the most common pathogens responsible for the infection, particularly Staphylococcus aureus and Streptococcus pyogenes. Cephalexin is a first-generation cephalosporin that possesses good activity against gram-positive cocci, making it well-suited for treating skin and soft tissue infections like impetigo.

Additionally, cephalexin has favorable pharmacokinetic properties, allowing for effective oral administration and good tissue penetration, which is necessary for resolving infections in the skin. This oral antibiotic's effectiveness, safety profile, and familiarity among clinicians contribute to its frequent use in treating extensive impetigo cases.

While the other options—amoxicillin, ciprofloxacin, and metronidazole—may have their places in treating various infections, they do not have the same targeted efficacy against the bacteria causing impetigo. Amoxicillin is generally less effective for treating skin infections due to its narrower spectrum against staphylococci. Ciprofloxacin is a fluoroquinolone that is primarily effective against gram-negative bacteria rather than the gram-positive organisms implicated in impetigo. Metronidazole is effective against anaerobic bacteria and