. 2021 Jan 6;16(1):e0244673. doi: 10.1371/journal.pone.0244673

Table 4. Chequerboard results of colistin in combination with aminoglycoside (amikacin, gentamicin and tobramycin) against colistin resistant K. pneumoniae isolates.

Isolates	Antibiotics	Combined MIC (μg/mL)	FICI	Fold reduction	Outcome
1NT4Ng/1	COL	8	0.281	32	Synergy
	AMI	4	0.281	4	Synergy
	COL	32	0.375	8	Synergy
	GEN	32	0.375	4	Synergy
	COL	64	0.500	4	Synergy
	TOB	8	0.500	4	Synergy
1NT6Ng/1	COL	8	0.281	32	Synergy
	AMI	4	0.281	4	Synergy
	COL	8	0.281	32	Synergy
	GEN	32	0.281	4	Synergy
	COL	64	0.500	4	Synergy
	TOB	8	0.500	4	Synergy
1NT6Tu/1	COL	64	0.265	4	Synergy
	AMI	0.12	0.265	64	Synergy
	COL	8	0.281	32	Synergy
	GEN	64	0.281	4	Synergy
	COL	ND	ND	ND	ND
	TOB	ND	ND	ND	ND
1NT6R	COL	16	0.078	16	Synergy
	AMI	0.25	0.078	64	Synergy
	COL	16	0.125	16	Synergy
	GEN	8	0.125	16	Synergy
	COL	32	0.375	8	Synergy
	TOB	16	0.375	4	Synergy
1NT7R	COL	ND	ND	ND	ND
	AMI	ND	ND	ND	ND
	COL	32	0.375	8	Synergy
	GEN	32	0.375	4	Synergy
	COL	ND	ND	ND	ND
	TOB	ND	ND	ND	ND
1NT8Th	COL	16	0.312	16	Synergy
	AMI	4	0.312	4	Synergy
	COL	64	0.500	4	Synergy
	GEN	16	0.500	4	Synergy
	COL	ND	ND	ND	ND
	TOB	ND	ND	ND	ND
1NT6Ng(CCU)/1	COL	16	0.281	32	Synergy
	AMI	4	0.281	4	Synergy
	COL	64	0.250	8	Synergy
	GEN	16	0.250	8	Synergy
	COL	64	0.375	8	Synergy
	TOB	4	0.375	4	Synergy
1NT6Th(CCU)/1	COL	8	0.062	32	Synergy
	AMI	0.5	0.062	32	Synergy
	COL	32	0.375	8	Synergy
	GEN	32	0.375	4	Synergy
	COL	16	0.312	16	Synergy
	TOB	4	0.312	4	Synergy
1NT6R(CCU)	COL	32	0.250	8	Synergy
	AMI	2	0.250	8	Synergy
	COL	32	0.187	8	Synergy
	GEN	8	0.187	16	Synergy
	COL	ND	ND	ND	ND
	TOB	ND	ND	ND	ND

CCU, Cardiac Care Unit; MIC, Minimum inhibitory concentrations; COL, Colistin; AMI, Amikacin; FICI, Fractional inhibitory concentration index; GEN, Gentamicin; TOB, Tobramycin; ND, not determined.