A 28-year-old man presents to an outpatient clinic with a 3-day history of an intensely pruritic eruption. He reports recently using a communal spa at his fitness center. He denies any similar rashes in the past and has no significant medical history, taking no regular medications. On examination, his temperature is 37.8°C, heart rate 72 bpm, blood pressure 120/78 mmHg, and respiratory rate 16 breaths/min. Inspection reveals numerous tender, erythematous papulopustules, prominently distributed across his torso, buttocks, and upper thighs, with some sparse lesions noted in the axillary regions. The lesions appear to be centered around hair follicles. Given the clinical presentation, what is the most likely diagnosis and the crucial preventative measure to avoid recurrence?

A 60-year-old woman with a known history of poorly controlled type 2 diabetes mellitus and hypertension presents to an urgent care clinic after sustaining a deep puncture wound to her right foot. She recounts stepping on a rusty metal shard while gardening in her backyard shed approximately 12 hours ago. She attempted to clean the wound herself but noticed increasing pain and a persistent low-grade fever over the last few hours. Her vital signs upon arrival are: temperature 38.0°C, blood pressure 165/98 mmHg, pulse 98 beats/min, respirations 16 breaths/min, and oxygen saturation 98% on room air. Physical examination reveals a small, deep puncture wound approximately 0.5 cm in diameter on the sole of her right foot, surrounded by a 3 cm area of erythema and mild tenderness to palpation, without purulent discharge at this time. There is no significant lymphangitic streaking. Peripheral pulses are palpable, and sensation is intact. Considering her complex medical history and presentation, what is the most appropriate initial empirical antibiotic therapy and what are the potential long-term complications if the infection is inadequately treated?

A 58-year-old woman with a history of systemic lupus erythematosus (SLE) well-controlled on maintenance corticosteroids presents to the general medical ward reporting a rapidly progressive, painful rash. She noticed a small red spot on her thigh yesterday, which has since dramatically expanded and developed a central black area. She reports feeling generally unwell with chills and body aches. Her vital signs upon admission are: temperature 39.5°C, blood pressure 95/60 mmHg, heart rate 118/min, respirations 22/min, and oxygen saturation 96% on room air. Physical examination reveals an ill-appearing woman. The affected area on her left thigh is a rapidly expanding, purplish-red lesion with an evolving necrotic center, approximately 8 cm in diameter, surrounded by an erythematous halo. The lesion is tender to palpation and has a dusky appearance. No crepitus is noted. Lymphadenopathy is absent. Given the clinical presentation, what is the most likely diagnosis and the immediate definitive treatment strategy?