Table 4.

Local antibiotic concentrations of vancomycin and tobramycin

Postoperative day	Vancomycin (µg/ml)a	Tobramycin (µg/ml)a
	Mean (range)	Mean (range)
1	265 (28.3–736.4)	31 (6.4–97.2)
2	172 (14.2–466.7)	9.4 (2.4–19.6)
3	146 (5.8–394.5)	6.4 (1.6–19.9)
4	146 (19.5–352.5)	5.3 (1.3–18.6)
5	104 (5.8–190.5)	4.6 (2.2–9.8)

^aAssayable values of antibiotics obtained from local exudate of drain samples. In the majority of assays conducted, maximum assayable limits for vancomycin and tobramycin were reported as > 400 µg/ml and > 20 µg/ml, respectively. As a result, mean values reported are lower than actual values