TABLE 5.

Percent reduction in meropenem, cefepime, cefazolin, and piperacillin concentrations over 12 h in BacT/Alert FA Plus Aerobic and Bactec Plus Aerobic/F blood culture bottles

Antibiotic	Category (observed 0-h concentration [μg/ml])a	Mean % reduction of observed zero concentration by test over:
		0.5 h		4 h		12 h
		BacT/Alert	Bactec Plus	BacT/Alert	Bactec Plus	BacT/Alert	Bactec Plus
Meropenemb	P (5.36)	42	38	54	65	68	79
	M (2.80)	43	47	52	68	69	78
	T (1.21)	49	56	58	77	70	77
Cefazolinc	P (15.04)	8	7	27	41	48	67
	M (1.97)	+2d	+4d	5	20	7	12
	T (0.46)	BDLg	BDL	BDL	BDL	BDL	BDL
Cefepimee	P (12.24)	66	+2d	75	44	88	64
	M (3.11)	60	+33d	76	23	BDL	50
	T (2.25)	BDL	+3d	BDL	16	BDL	46
Piperacillinf	P (19.13)	19	8	BDL	83	BDL	BDL
	M (5.14)	43	27	BDL	BDL	BDL	BDL
	T (1.49)	BDL	BDL	BDL	BDL	BDL	BDL

^aZero-hour concentration in blood culture bottles was 50% of the observed concentration in whole blood, divided by 4 to account for dilution in each bottle (10 ml whole blood inoculated with antibiotic and 30 ml blood culture media). P, peak; M, midpoint; T, trough.

^bThe lower limit of detection for meropenem was 0.25 μg/ml.

^cThe lower limit of detection for cefazolin was 0.5 μg/ml.

^dPositive numbers denote that the observed concentration was higher than that at 0 h, suggesting no binding reductions in the first 0.5 h.

^eThe lower limit of detection for cefepime was 0.5 μg/ml.

^fThe lower limit of detection for piperacillin was 2 μg/ml.

^gBDL, below detectable limit.