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\ ˈkōks- 
, ˈkäch-əz- \
, ˈkäch-əz- \variants:
or Koch bacillus \ ˈkōk- , ˈkäch- \
, ˈkäch- \Medical Definition of Koch's bacillus
: a bacillus of the genus Mycobacterium (M. tuberculosis) that causes human tuberculosis
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