Mycobacterium avium subspecies paratuberculosis in the etiology of Crohn’s disease, cause or epiphenomenon?

Table 2 Direct methods for dectection of Mycobacterium avium subspecies paratuberculosis

Method	Tissue analyzed	Ref.	+/-	Advantage	Defect
MAP culture				Effective isolation of microorganism	Organism’s fastidious nature; slow-growth
	Intestinal biopsy	[55]	+
	Peripheral blood	[57,59,60]	-
PCR for MAP-specific IS900 DNA				Fast and easy isolation of MAP fragment	Not able to distinguish vital MAP vs fragment of killed MAP;confounded by frequent MAP opportunistic infection (oro-fecal route)
	Intestinal biopsy	[53-55]	+
	Peripheral blood	[58]	+
	Peripheral blood	[59,60]	-
	Stools	[63]	-
PCR for MAP-specific IS900 DNA				Demonstrate the presence of active/vital metabolic processes	Difficult to reproduce (RNA half-life measured in min)
	Intestinal biopsy	[62]	+

+: Supporting Mycobacterium avium subspecies paratuberculosis (MAP) hypothesis; -: Contrasting MAP hypothesis; PCR: Polymerase chain reaction; IS900: Insertion sequence 900; DNA: Deoxyribonucleic acid; RNA: Ribonucleic acid.