Table 3. Ampicillin and cefoxitin susceptibility testing (MIC µg ml⁻¹).

Strain	Genotype	AMP*	AMP+S*	AMP+T*	AMP+C*	CEF
PM3044	WT M. abscessus	>256	>256	256	256	32
mc2155	WT M. smegmatis	256	64	32	16	nd
PM3386	ΔMAB_2875	32	nd	nd	nd	16
PM3389	ΔMAB_2833 :: aacC41	>256	nd	nd	nd	32
PM3395	ΔMAB_2875 ΔMAB_2833 :: aacC41	32	nd	nd	nd	32
PM3404	ΔMAB_2875/pMV261	8	nd	nd	nd	nd
PM3405	ΔMAB_2875/pMP1205	>256	nd	nd	nd	nd

*Key: AMP, ampicillin; AMP+S, ampicillin with 4 µg ml⁻¹ sulbactam; AMP+T, ampicillin with 4 µg ml⁻¹ tazobactam;, AMP+C, ampicillin with 4 µg ml⁻¹ clavulanic acid; CEF, cefoxitin; nd, not determined.