Mycobacterium leprae

Which single clinical feature best distinguishes tuberculoid leprosy from lepromatous leprosy?

A 38-year-old man from rural Maharashtra presents with a 2-year history of progressive numbness in his feet and hands. On examination, he has well-demarcated hypopigmented macules over his trunk and extensor surfaces with loss of sensation in these lesions. His ulnar and posterior tibial nerves are thickened and tender. Slit-skin smear from the lesion shows acid-fast bacilli. Which of the following best describes the classification of his leprosy based on clinical and bacteriological findings?

A 32-year-old man from rural Maharashtra presents with hypopigmented macules on his face and trunk with loss of sensation over the lesions. Clinical examination reveals thickened ulnar and posterior tibial nerves. Which investigation is most appropriate to confirm the diagnosis of leprosy?

A 28-year-old woman from endemic area presents with a single hypopigmented macule on her arm with impaired sensation. Slit-skin smear examination is negative for acid-fast bacilli. Which investigation is most appropriate to confirm early/indeterminate leprosy?

Which of the following is the primary reason Mycobacterium leprae cannot be cultured on standard laboratory media?