TABLE 1.

Genotypic and phenotypic susceptibility of tested agents against 8 clinical SME-producing S. marcescens isolates

Isolate	β-Lactamasea	MIC (mg/liter) ofb:
		AMP	ATM	CFZ	CAZ	CFP	GEN	IMI	LFX	MER	TMP-SMZc
SM-1	SME-4, SRT-2	≥256	64	≥256	1	0.25	1	≥256	0.125	128	0.5
SM-2	SME-4, SRT-1, SRT-2	≥256	64	≥256	0.5	0.25	1	≥256	0.125	128	0.5
SM-3	SME-4, SRT-2	≥256	32	≥256	0.125	0.25	0.5	≥256	0.125	128	0.5
SM-4	SME-4, SRT-2	≥256	64	≥256	1	1	1	≥256	0.125	128	0.5
SM-5	SME-4, SRT-2	≥256	64	≥256	0.5	1	1	≥256	0.25	128	1
SM-6	SME-4, SRT-2	≥256	128	≥256	1	0.25	1	≥256	0.125	128	0.25
SM-7	SME-4, SST-1	≥256	64	≥256	0.5	0.125	1	≥256	0.125	128	0.5
SM-8	SME-4, SRT-2	≥256	64	≥256	0.25	0.125	0.5	≥256	0.125	≥256	0.5

^aSME, S. marcescens enzyme; SRT, class C cephalosporinase from S. marcescens hydrolyzing the 2-carboxypenam T-5575; SST, produced by β-lactam-susceptible strain of S. marcescens.

^bAMP, ampicillin; ATM, aztreonam; CFZ, cefazolin; CAZ, ceftazidime; CFP, cefepime; GEN, gentamicin; IMI, imipenem; LFX, levofloxacin; MER, meropenem; TMP-SMZ, trimethoprim-sulfamethoxazole.

^cMIC of trimethoprim component only.