Paromomycin production from Streptomyces rimosus NRRL 2455: statistical optimization and new synergistic antibiotic combinations against multidrug resistant pathogens

Table 8 Effects of different antimicrobial combinations on Paromomycin activity among selected isolates

No.	Species	Antimicrobial combination	Concentrations^a(μg/ml)	ΣFIC^b	Interpretation
PS4	P .aeruginosa	Paromomycin/ceftriaxone	32/256	0.375	S
		Paromomycin/ciprofloxacin	128/1	0.53125	A
		Paromomycin/azithromycin	8/256	0.28125	S
		Paromomycin/ampicillin-sulbactam	4/(85.33/42.67)	0.51625	A
PS25	P. aeruginosa	Paromomycin/ceftriaxone	32/64	0.75	A
		Paromomycin/ciprofloxacin	16/1	0.3125	S
		Paromomycin /azithromycin	4/16	1.03125	I
		Paromomycin/ampicillin-sulbactam	8/(21.33/10.67)	0.625	A
KP13	K. pneumoniae	Paromomycin/ceftriaxone	0.5/2	0.515625	A
		Paromomycin/ciprofloxacin	0.25/256	0.5	S
		Paromomycin/azithromycin	0.25/32	0.75	A
		Paromomycin/ampicillin-sulbactam	1/(0.67/0.33)	1.03125	I
EC10	E.coli	Paromomycin/ceftriaxone	1/16	0.3125	S
		Paromomycin /Ciprofloxacin	1/0.125	0.5	S
		Paromomycin/azithromycin	0.25/0.25	0.5	S
		Paromomycin/ampicillin-sulbactam	0.5/(1.33/0.67)	0.1875	S
PS36	MRSA	Paromomycin/ceftriaxone	256/16	0.140625	S
		Paromomycin/ciprofloxacin	256/8	0.1875	S
		Paromomycin/clindamycin	512/0.25	0.75	A
		Paromomycin/doxycycline	64/0.5	0.53125	A
PS41	MSSA	Paromomycin/ceftriaxone	512/8	0.75	A
		Paromomycin/ciprofloxacin	32/128	1.015625	I
		Paromomycin/clindamycin	1024/0.125	0.625	A
		Paromomycin/doxycycline	64/0.5	0.28125	S

^a Concentrations of the respective antimicrobials agents at which the lowest value of ΣFIC was achieved.
^bΣFIC, the sum of the fractional inhibitory concentrations of the combined antimicrobial agents.A, additive effect; I, indifferent effect; S, synergistic effect

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