TABLE 3.

MIC and susceptibility patterns predictive of ESBL production

Strain and susceptibility pattern	No. of strains that were:		Sensitivity (%)	Specificity (%)	Positive predictive value (%)
	ESBL positive	ESBL negative
All strains	93	494
Cefepime MIC, >0.25 μg/ml	93	129	100	74	42
Aztreonam MIC, >1 μg/ml	93	159	100	68	37
Ceftazidime MIC, >2 μg/ml	92	166	99	68	37
Ceftriaxone MIC, >1 μg/ml	93	163	100	67	36
Piperacillin-tazobactam MIC, ≤16 μg/ml	63	365	68	26	15
Nalidixic acid MIC, >8 μg/ml	69	84	74	83	45
Ciprofloxacin MIC, >1 μg/ml	35	43	38	91	45
Tetracycline MIC, >8 μg/ml	63	55	68	92	62
Gentamicin MIC, >4 μg/ml	64	41	69	92	63
Trimethoprim-sulfamethoxazole MIC, >1 μg/ml	79	47	69	88	56
Subset of strains for which ceftazidime MICs were >2 μg/ml or ceftriaxone MICs were >1 μg/ml	93	167
Cefepime MIC, >0.25 μg/ml	93	124	100	26	43
Piperacillin-tazobactam MIC, ≤16 to 4 μg/ml	61	38	68	77	62
Nalidixic acid MIC, >8 μg/ml	69	63	74	62	52
Ciprofloxacin MIC, >1 μg/ml	35	37	38	78	49
Gentamicin MIC, >4 μg/ml	64	37	69	78	63
Tetracycline MIC, >8 μg/ml	63	55	68	78	64
Trimethoprim-sulfamethoxazole MIC, >1 μg/ml	79	45	85	73	64