TABLE 2.

Antimicrobial susceptibility tests of P. aeruginosa ATCC 27853 and β-lactam agents by the novel ATP-bioluminescence method, the standard ATP-bioluminescence method, and the microdilution method

Antimicrobial agent (MIC [μg/ml]a)	Concn (μg/ml)	Novel ATP method			Standard ATP method			Result with microdilution methodd
		Bioluminescence (RLU)	ATP indexb	Resultc	Bioluminescence (RLU)	ATP indexb	Resultc
Piperacillin (3.13)	5	63	13.3	−	310	76.0	+	−
	10	81	17.2	−	516	126.5	+	−
	30	40	8.5	−	208	51.0	+	−
Cefoperazone (6.25)	2	128	27.1	−	471	115.4	+	−
	10	58	12.3	−	443	108.6	+	−
	25	45	9.5	−	489	119.9	+	−
Aztreonam (6.25)	3	241	51.1	+	495	121.3	+	+
	10	57	12.1	−	517	126.7	+	−
	50	52	11.0	−	560	137.3	+	−
Imipenem-cilastatin (1.56)	3	35	7.4	−	408	100.0	+	−
	10	27	5.7	−	280	68.6	+	−
	50	25	5.3	−	289	70.8	+	−
Ceftazidime (1.56)	3	54	11.4	−	578	141.7	+	−
	10	66	14.0	−	568	139.2	+	−
	100	21	4.4	−	566	138.7	+	−
Cefsulodin (1.56)	5	80	16.9	−	274	67.2	+	−
	15	91	19.3	−	317	77.7	+	−
	40	75	15.9	−	402	98.5	+	−
Cefazolin (≥100)	3	358	75.8	+	226	55.4	+	+
	15	411	87.1	+	220	53.9	+	+
	60	391	82.8	+	241	59.1	+	+
Controle	0	472	100.0	+	408	100.0	+	+

^aDetermined by the standard agar dilution method. 

^bCalculated as (bioluminescence in broth with antimicrobial agent/bioluminescence in broth without antimicrobial agent) × 100. 

^c−, ATP index ≤ 40; +, ATP index > 40. 

^d−, no growth; +, growth. 

^eResults for drug-free conditions are shown.