Polymyxin Combination Therapy and the Use of Serum Bactericidal Titers in the Management of KPC-Producing Klebsiella pneumoniae Infections: A Report of 3 Cases

Table 1

Peak and trough serum inhibitory/bactericidal titers.

		Peak		Trough		MIC (𝜇g/mL) by Etest
	Isolate	SIT	SBT	SIT	SBT	DOR	PO	TG	RIF
Case 1	Patient	1 : 32	1 : 32	1 : 16	1 : 16	>32	0.5
	NYHQ KP	1 : 4	1 : 4	1 : 4	1 : 4	3	6
	E. coli	>1 : 1024	>1 : 1024	>1 : 1024	>1 : 1024	0.016	0.5	0.125	12
	KP SHV-18	1 : 256	1 : 256	1 : 128	1 : 128	0.064	1	ND	>32
Case 2	Patient	1 : 32	1 : 32	1 : 32	1 : 16	16	2	3-4
Case3	Patient	1 : 8	1 : 8	1 : 8	1 : 8	3	3		>32
	NYHQ KP	1 : 8	1 : 8	1 : 8	1 : 8	>32	32		>32

SIT: serum inhibitory titers; SBT: serum bactericidal titers; MIC: minimal inhibitory concentration; DOR: doripenem; PO: polymyxin B; TG: tigecycline; RIF: rifampin; KP: Klebsiella pneumoniae; ND: not done.