TABLE 3.

Percent reduction in meropenem, cefepime, cefazolin, and piperacillin concentrations over 12 h in BacT/Alert FN Plus anaerobic and Bactec Plus anaerobic/F blood culture bottles^a

Antibiotic	Category (observed 0 h concentration in bottle [BacT Alert/Bactec Plus], μg/ml)b	Mean % reduction of observed zero concentration
		0.5 h		4 h		12 h
		BacT/Alert	Bactec Plus	BacT/Alert	Bactec Plus	BacT/Alert	Bactec Plus
Meropenemc	P (4.29/5.36)	BDL	27	BDL	51	BDL	71
	M (2.24/2.80)	BDL	38	BDL	50	BDL	77
	T (0.97/1.21)	BDL	52	BDL	62	BDL	74
Cefazolind	P (12.03/15.04)	35	51	51	77	63	86
	M (1.58/1.97)	36	+15e	51	31	63	52
	T (0.37/0.46)	BDL	BDL	BDL	BDL	BDL	BDL
Cefepimef	P (9.79/12.24)	51	+6e	61	20	71	54
	M (2.49/3.11)	49	+69e	59	+12e	71	32
	T (1.80/2.25)	BDL	+63e	BDL	+4e	BDL	27
Piperacilling	P (15.31/19.13)	83	22	BDL	75	BDL	BDL
	M (4.11/5.14)	BDL	35	BDL	BDL	BDL	BDL
	T (1.20/1.49)	BDL	BDL	BDL	BDL	BDL	BDL

^aP, peak; M, midpoint; T, trough; h, hour; BDL, below detectable limit.

^bZero hour concentration in blood culture bottles was 50% of the observed concentration in whole blood, divided by 5 (BacT/Alert) or 4 (Bactec Plus) to account for dilution in each bottle (10 ml whole blood inoculated with antibiotic, 40 ml blood culture media in BacT/Alert bottles, 30 ml blood culture media in Bactec Plus bottles).

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

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

^ePositive numbers denote that the observed concentration was higher than the 0 h, suggesting that no binding reductions were observed.

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

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