A 28-year-old woman is admitted to the general medical ward presenting with a 10-day history of escalating joint pain, malaise, and intermittent fever. Her symptoms began with pain in her right wrist and elbow, which later migrated to affect her left knee predominantly. She reports generalized fatigue and a low-grade fever over the past week. Upon admission, her temperature is 38.50C (101.30F), blood pressure 105/70 mm Hg, pulse 102/min, and respiratory rate 18/min. Physical examination reveals a warm, tender left knee with a mild effusion but no significant erythema, and painful active and passive range of motion. There is notable tenderness and swelling along the extensor tendons of her right wrist and fingers, indicative of tenosynovitis. Additionally, a few scattered, non-itchy pustular lesions with erythematous bases are observed on her right index finger and palm. There is no significant lymphadenopathy or cardiac murmurs. She mentions a recent change in sexual partners and inconsistent condom use. Given this patient's comprehensive clinical picture, what is the most likely diagnosis and the crucial initial diagnostic and therapeutic steps to undertake?

A 28-year-old man presents for a routine follow-up visit in an outpatient general medicine clinic. He recently recovered from an episode of disseminated gonococcal infection (DGI) that manifested as tenosynovitis and migratory polyarthralgia, successfully treated with intravenous ceftriaxone. He reports no residual symptoms and feels completely well. His medical history is otherwise unremarkable, and he takes no chronic medications. He mentions that his older brother experienced a severe, non-fatal meningococcal infection requiring hospitalization several years ago. On physical examination, his vital signs are stable: temperature 36.8 °C, heart rate 72 beats/min, blood pressure 128/78 mmHg, and respiratory rate 16 breaths/min. The general examination is unremarkable, with no active inflammation or rash, and all joints have full range of motion without tenderness. Given his clinical history and family background, what is the most likely underlying immune deficiency and the crucial management step that follows diagnosis?

A 25-year-old woman is seen in an outpatient clinic due to concern for a sexually transmitted infection after her new male partner was recently diagnosed with uncomplicated urethral gonorrhea. She reports intermittent mild throat discomfort and occasional difficulty swallowing for two weeks. She denies any other symptoms or significant medical history. On physical examination, vital signs are stable. Oropharyngeal exam reveals mild erythema without exudates or ulcerations. No significant cervical lymphadenopathy. Abdominal and pelvic exams are unremarkable. Given her presentation and exposure history, which initial diagnostic evaluation and empiric treatment approach would be most appropriate?

A 32-year-old male presents to an outpatient clinic with a 5-day history of progressively worsening dysuria and a yellowish-green penile discharge. He reports having unprotected sexual encounters with new partners in the past month. He denies fever, chills, or testicular pain. On physical examination, he appears otherwise well. There is mucopurulent discharge from the urethral meatus, and tender, enlarged bilateral inguinal lymph nodes are palpable. No genital ulcers or skin lesions are observed. A urethral swab is performed. What is the most likely diagnosis and the recommended initial management, including an essential follow-up consideration?