TABLE 3.

Frequency of apparent resistance in daptomycin-nonsusceptible MRSA strains C4 and C37 sensitive to each phage^a,b,c

Strain	Treatment	Timepoint (h)	Colony count	Mean CFU/g in sample	Apparent FoR	LoD (1/CFU on plate)
C4
	No antibiotic
	Intesti13 + Sb-1	0	0	2.56 × 108	<LoD	4.15 × 108
		168	Est. 1,000	7.42 × 108	5.84 × 10−5	7.89 × 108
	DAP	0	0	2.89 × 108	<LoD	2.53 × 108
		168	523	5.21 × 108	5.84 × 10−7	6.47 × 108
	Intesti13 + Sb-1	0	0	4.78 × 108	<LoD	9.03 × 108
		168	167	6.34 × 108	<LoD	5.72 × 108
	DAP + CPT	0	0	9.15 × 108	<LoD	8.26 × 108
	Intesti13 + Sb-1	168	0	8.47 × 108	<LoD	3.68 × 108
C37
	No antibiotic
	Intesti13 + Sb-1	0	0	1.29 × 108	<LoD	7.49 × 108
		168	Est. 1,000	2.53 × 108	3.74 × 10−5	1.34 × 108
	DAP	0	0	4.62 × 108	<LoD	8.52 × 108
		168	449	5.93 × 108	4.15 × 10−7	3.74 × 108
	Intesti13 + Sb-1	0	0	3.47 × 108	<LoD	2.68 × 108
		168	307	6.28 × 108	4.15 × 10−7	4.93 × 108
	DAP + CPT	0	0	7.54 × 108	<LoD	2.65 × 108
	Intesti13 + Sb-1	168	0	8.39 × 108	<LoD	9.17 × 108

^a Abbreviations: CFU, colony-forming unit; FoR, frequency of resistance; LoD, limit of detection; DAP, daptomycin; CPT, ceftaroline.

^b FoR: [colonies that arise on the resistance plate]/[CFU per milliliter used to create the plate].

^c LoD: If <LoD is indicated, then the apparent FoR equals 0.