Mechanisms of in vitro sensitivity to sulfadiazine silver
A. T. McManus, C. L. Denton and A. D. Mason Jr
Sulfonamide-resistant organisms have been reported as a frequent
consequence of the clinical use of sulfadiazine silver. At this burn
center, sulfonamide resistance occurred in more than 80% of gram-negative
isolates. We tested the requirement for the individual antimicrobial
activities of sulfadiazine and silver for the vitro activity of
sulfadiazine silver. The sulfadiazine component is not necessary for in
vitro sensitivity. In vitro sensitivity to sulfadiazine silver does not
consistently predict the presence of therapeutic activity in Pseudomonas
aeruginosa-infected rats with burns. We describe an example of a
transferable multiple-antibiotic resistance plasmid that contains
selectable sulfonamide resistance. The use of sulfadiazine silver can,
therefore, lead to the selection of organisms that are resistant not only
to sulfonamides but to antibiotics of clinical consequence, and this
possible risk must be considered in electing to use the agent.
