What is an appropriate additional treatment for a 16-year-old with moderate acne that has not responded to topical clindamycin?

In cases of moderate acne that fails to respond to topical treatments such as clindamycin, an appropriate next step in management is the use of oral antibiotics, such as doxycycline. Doxycycline is a tetracycline antibiotic that not only helps combat the bacterial component of acne by reducing Propionibacterium acnes (the bacteria linked to acne development) but also possesses anti-inflammatory properties. This is particularly beneficial in reducing the inflammation associated with moderate to severe acne lesions.

Oral doxycycline is often chosen for its effectiveness in treating inflammatory acne and its ability to reach deeper skin layers where topical treatments may not be sufficient. This systemic approach is warranted when there is moderate acne that has not adequately responded to topical agents, as it provides a more comprehensive effort to control acne and improve the patient's skin condition.

In contrast, intralesional steroids would be more relevant for treating individual cystic lesions rather than for generalized moderate acne. Benzoyl peroxide is a valuable adjunct to topical treatments but is not sufficient alone if the patient is already on clindamycin and still experiencing acne. Metronidazole cream is primarily used for rosacea and is not indicated for acne treatment, making it an unsuitable option in this scenario.