Which skin condition is characterized by the presence of a contagious bacterial infection?

Impetigo is a highly contagious bacterial skin infection that is usually caused by the Staphylococcus aureus or Streptococcus pyogenes bacteria. It often presents as red sores, blisters, or lesions, which can ooze and form a yellow-brown crust. This condition is particularly common among children and can spread easily through direct contact or by sharing personal items.

Acne vulgaris, while common, is not contagious and results from the clogging of hair follicles with oil and dead skin cells, often exacerbated by hormonal changes. Eczema is a chronic inflammatory skin condition that can cause dry, itchy patches but is primarily linked to genetic and environmental factors rather than bacterial infections. Psoriasis is an autoimmune condition characterized by the rapid proliferation of skin cells leading to thick, red, scaly patches and is also not contagious. Thus, impetigo is distinctly categorized by its infectious nature, making it the correct answer in this context.