(mī'kō-bak-tēr'ē-ŭm hē-mof'i-lŭm) A nonchromogenic acid-fast bacillus; infections occur mainly in immunocompromised patients (e.g., those with AIDS, Hodgkin disease). Submandibular lymphadenitis, subcutaneous nodules, and ulcers that progress to abscesses and fistulae are common manifestations.