Ag+ (silver cation) has antimicrobial properties and is used in a broad range of applications (urinary catheter, burn wound cream, etc) as a topical agent. Resistance can develop in some Gram-negative bacteria.
Susceptible bacteria showed a silver nitrate MIC <= 8 mg/L.
High level resistance is indicated by a silver nitrate MIC > 128 mg/L
There may be 2 forms of resistance:
(1) overt
(2) cryptic (inducible), seen in Enterobacter and Klebsiella species
The cryptic resistance is associated with the sil operon.
The cryptic form can be identified by plating a saturated culture of a Gram-negative isolate onto agar containing supra-inhibitory concentrations of silver ions (128 mg silver nitrate per L) with overnight incubation.
To read more or access our algorithms and calculators, please log in or register.
