A clinical and bacteriological examination of Mycobacterium leprae in the epidermis and cutaneous appendages of patients with multibacillary leprosy.

In the specimens examined at Ryukyu University Hospital, acid-fast bacilli (AFB) were observed in the epidermis, cutaneous appendages and endothelial cells of capillaries. These specimens were taken from non-ulcerating skin lesions of patients with multibacillary leprosies such as LL and borderline lepromatous leprosy (BL). Of the 211 specimens examined, 23 (10.9%) were AFB-positive [AFB (+)] in the above mentioned skin regions. These AFB (+) samples were taken from nine leprosy patients; six cases (17 samples) of LL, two cases (5 samples) of BL, and one case (one sample) of BB. The AFB positive rate [AFB (+)-rate] in the above mentioned skin regions was high in the unmedicated LL sample (50.0%, 7/14) and low in the medicated mid-borderline leprosy (BB) samples (0.0%, 0/10). Particularly in the intraepidermal eccrine sweat duct (acrosyringium), a relatively high number of AFB were observed. The AFB (+)-rate appears likely to be higher in non-ulcering skin lesions with minor inflammation or in lesions with leprosy reaction than typical skin lesions such as papules, nodules, and infiltrated punched out skin lesions. Although the possibility that viable bacilli could be excreted from non-ulcerating skin lesions appeared to be small, these lesions were suspected of being a possible source of infection.