TABLE 5.

Comparative activity of piperacillin-tazobactam and other parenterally administered antibiotics against aerobic Gram-negative bacilli isolated in four Canadian regions

Organism	Percentage of strains susceptible to
	Piperacillin-tazobactam					Piperacillin					Ticarcillin-clavulanate
	Atlan	Que	Ont	West	P	Atlan	Que	Ont	West	P	Atlan	Que	Ont	West	P
Escherichia coli	99	97	98	99	0.670	73	76	71	77	0.22	95	92	91	93	0.74
Klebsiella species	91	100	94	96	0.00055	75	88	78	88	0.0018	89	99	93	99	0.001
Enterobacter species	78	89	85	92	0.035	75	87	81	90	0.013	75	83	75	86	0.022
Proteus-Providentia group	100	99	99	99	1.00	93	93	97	95	0.39	96	96	98	98	0.71
Pseudomonas aeruginosa	98	94	97	95	0.082	97	94	96	94	0.24	85	90	88	89	0.58F

^*Fishers exact test. Atlan Atlantic; Ont Ontario; Que Quebec; West Western provinces