Propranolol restores susceptibility of XDR Gram-negative pathogens to meropenem and Meropenem combination has been evaluated with either tigecycline or amikacin

Table 4 The calculated FIC index values of the MEM + AK and MEM + TGC combinations against 28 XDR CR pathogens

Isolate code	MIC of antimicrobial agents (µg/ml)/Susceptibility			MEM + AK		MEM + TGC
Isolate code	MEM	AK	TGC	FIC index	Interpretation ^a	FIC index	Interpretation ^a
AB-9G	256/R	1024/R	2/S	0.531	Additive	1.063	Indifferent
AB-109A	256/R	1024/R	0.5/S	0.531	Additive	1	Indifferent
AB-63 M	1024/R	64/R	0.5/S	0.516	Additive	1	Additive
AB-30G	512/R	16/S	2/S	1	Additive	0.75	Additive
AB-100 M	1024/R	512/R	2/S	0.75	Additive	0.75	Additive
AB-55 M	1024/R	512/R	1/S	0.625	Additive	1	Additive
AB-20G	256/R	64/R	1/S	1.5	Indifferent	0.75	Additive
AB-3 M	512/R	512/R	4/I	0.625	Additive	0.531	Additive
AB-14 M	128/R	256/R	0.5/S	1	Additive	1	Additive
AB-37 M	1024/R	128/R	2/S	0.516	Additive	0.75	Additive
AB-34 M	128/R	64/R	1/S	1	Additive	1	Additive
AB-13 M	512/R	64/R	2/S	0.531	Additive	1.031	Indifferent
AB-7G	512/R	64/R	2/S	0.531	Additive	0.75	Additive
KP-84S	64/R	256/R	4/I	0.625	Additive	0.75	Additive
KP-25S	1024/R	1024/R	4/I	0.75	Additive	0.531	Additive
KP-89S	128/R	256/R	4/I	1	Additive	0.75	Additive
KP-106S	512/R	512/R	2/S	0.625	Additive	1.031	Indifferent
KP-114S	1024/R	16/S	0.5/S	0.625	Additive	1	Additive
KP-92A	1024/R	64/R	4/I	0.516	Additive	0.531	Additive
KP-79A	512/R	64/R	4/I	0.531	Additive	0.531	Additive
KP-113S	512/R	512/R	1/S	0.625	Additive	1.063	Indifferent
PA-78S	128/R	64/R	256/R	1.5	Indifferent	1	Additive
PA-99S	1024/R	128/R	512/R	0.516	Additive	0.625	Additive
PA-50S	256/R	1024/R	1024/R	0.531	Additive	0.75	Additive
PA-54S	1024/R	512/R	128/R	0.625	Additive	0.516	Additive
EC-55A	512/R	16/S	1/S	1	Additive	1.031	Indifferent
EC-99A	256/R	16/S	0.5/S	0.625	Additive	1.25	Indifferent
EC-34R	64/R	1/S	0.5/S	0.625	Additive	1.063	Indifferent

Abbreviations: FIC index fractional inhibitory concentration index, MEM meropenem, AK amikacin, TGC tigecycline, AB A. baumannii, KP K. pneumoniae, PA P. aeruginosa, EC E. coli
^a FIC index was calculated using the lowest concentration of the respective antimicrobial agents at which the lowest value of FIC was achieved. Synergism ≤ 0.5, additive > 0.5—≤ 1, indifference > 1—≤ 4, antagonism > 4 [37]

ISSN: 1471-2180