TABLE 3.

Distribution of interpretive discrepancies and categorical error rates by antimicrobial agent tested

Antimicrobial agent	No. of organism- antimicrobial combinations tested	% of inter- pretative discrep- anciesa	% of errors of type
			Minora	Majorb	Very majorc
Piperacillin-tazobactam	809	21.2	13.9	9.1	7.7
Ceftriaxone	352	19.6	10.8	15.6	5.2
Cefotaxime	647	17.0	10.2	6.4	8.0
Ceftazidime	892	11.8	4.8	8.9	5.1
Cefepime	903	30.5	13.9	16.9	19.3
Aztreonam	848	22.1	13.9	13.6	6.6
Imipenem	919	2.4	1.6	0.6	1.9
Meropenem	829	6.6	3.6	3.0	0
Total	6,199	15.9d	8.8d	7.6	7.8

^aConsidering the number of susceptibility testing determinations for each antibiotic as the denominator.

^bConsidering the number of susceptible strains for each antibiotic as the denominator.

^cConsidering the number of resistant strains for each antibiotic as the denominator.

^dConsidering the total number of susceptibility testing determinations as the denominator.