Bacterial Structure and Staining

A 32-year-old male farmer from rural Maharashtra presents with a painless, indurated ulcer on his left hand that appeared 3 weeks ago after a thorn prick. On examination, the ulcer has a characteristic 'punched-out' appearance with rolled edges. A biopsy specimen is sent for histopathology and acid-fast staining. The pathologist reports numerous acid-fast bacilli within foamy macrophages. Which of the following bacterial structural features is primarily responsible for the acid-fast staining property observed in this organism?

Which of the following bacterial structures is composed of peptidoglycan and is responsible for maintaining cell shape and rigidity?

In Gram staining, which of the following is the mordant that forms a complex with crystal violet and allows retention of the dye in Gram-positive bacteria?

A 32-year-old woman presents with a painless ulcer on her genitalia with indurated borders and a clean base. Dark-field microscopy of the exudate reveals motile, spiral-shaped organisms. What is the drug of choice for treatment of this infection?

A 28-year-old man from rural India presents with fever, headache, and a petechial rash on his trunk and extremities. Gram stain of cerebrospinal fluid shows gram-negative diplococci. What is the drug of choice for empiric treatment of bacterial meningitis in this patient?