The inoculum effect of antibiotics against CTX-M-extended-spectrum β-lactamase-producing Escherichia coli

Table 1 The inoculum effects on six antimicrobial agents for 80 strains of Escherichia coli at standard and high-inoculum

Antimicrobial agent	MIC (μg/ml)at standard and high inoculum						Number of strains showing an inoculum effect	*Escherichia coli*ATCC25922
	Standard inoculum			High inoculum
	(1-5 × 10⁵CFU/ml inoculum)			(1-5 × 10⁷ CFU/ml inoculum)
	Range	MIC50	MIC90	Range	MIC50	MIC90
Meropenem	≤0.015 ~ 0.06	0.03	0.03	0.03 ~ 0.06	0.03	0.06	0	≤0.015
Cefminox	0.5 ~ 4	1	2	0.5 ~ 8	2	4	0	2
Piperacillin/tazobactam	4 ~ 32	8	32	8 ~ 256	8	64	4	2
Ceftazidime	1 ~ 32	4	16	8 ~ 128	32	64	28	0.25
Cefepime	4 ~ 32	8	32	32~ > 512	512	>512	68	0.12
Cefotaxime	16 ~ 256	64	256	128~ > 512	512	>512	80	0.12

ISSN: 1476-0711