TABLE 1.

Comparison of agar dilution and broth microdilution method MICs for the three participating laboratories interpreted at 24 and 48 h^a

Antimicrobial agent	Value at 24 h/value at 48 h
	Correlation coefficient (r)	Regression slope
Amikacin	0.92/0.92	0.98/0.95
Gentamicin	0.96/0.96	1.00/1.00
Tobramycin	0.94/0.93	1.02/1.00
Ciprofloxacin	0.86/0.86	0.86/0.87
Piperacillin	0.88/0.83	0.89/0.91
Ticarcillin	0.89/0.88	0.92/0.86
Piperacillin-tazobactam	0.88/0.92	0.93/0.98
Ticarcillin-clavulanate	0.87/0.88	0.96/0.98
Ceftazidime	0.91/0.93	0.93/0.90
Aztreonam	0.88/0.87	0.87/0.86
Imipenem	0.88/0.85	0.85/0.76
Meropenem	0.88/0.87	0.87/0.87

^an = 6,999 comparisons.