Table 4.

Gene mutations in NTM species

Species/Subspecies	erm(41)a		rrld		rrse
	C28b	T28c	WT	MUT	WT	MUT
M. avium			1		1
M.intracellulare			26		26
M. chimaera			1		1
M. abscessus subsp. abscessus	2		2		2
M. abscessus subsp. massiliense	6		6		6
M. abscessus subsp. bolletti	0	0	0	0	0	0

Note: The probes erm(41) C28 and erm(41) T28 are only relevant for M. abscessus subsp. abscessus and M. abscessus subsp. bolletii, but not for M. abscessus subsp. massiliense. Due to deletions in the erm(41) gene of M. abscessus subsp. massiliense the gene is nonfunctional, leading to macrolide sensitivity in spite of a developed erm(41) T28 band (except for strains with an additional rrl mutation)

WT wild type probe comprises the most important resistance region of the rrl and rrs genes, MUT mutation probes detect the most common resistance-mediating mutations in rrl and rrs genes

^aThe erm(41) gene is examined for detection of resistance to macrolides (Clarithromycin or azithromycin) and is only present in members of the M. abscessus complex

^bThe erm(41) C28 probe detects a genotype that carries a C at position 28 of the erm(41) gene. When the erm(41) C28 probe stains positive, this indicates that the tested strain is sensitive to macrolides (except for strains with an additional rrl mutation)

^cThe erm(41) T28 probe detects a genotype that carries a T instead of a C at position 28 of the erm(41) gene. When the erm(41) T28 probe stains positive, this indicates that the tested strain is resistant to macrolides

^dThe rrl gene is examined for detection of resistance to macrolides (clarithromycin or azithromycin)

^eThe rrs gene is examined for detection of resistance to aminoglycosides (kanamycin, amikacin, gentamicin)