Comparison of in vitro disc diffusion and time kill-kinetic assays for the evaluation of antimicrobial wound dressing efficacy.
There is a plethora of new silver-containing dressings on the market today. Various manufacturers attempt to show that their dressings are the most efficacious and therefore should be preferentially employed by health care workers based on the results of their in vitro tests. However, there have been no studies that clearly identify which tests are appropriate for comparison purposes. The purpose of this study was to determine which in vitro test is most appropriate for evaluating the antimicrobial efficacy of silver-containing dressings. This was done by testing seven silver-containing dressings and two non-silver-containing topical agents against 17 clinically relevant microorganisms using zone of inhibition assays and time-kill kinetic assays in complex media. The results for the two assays were then correlated to determine whether the methods generated similar results. It was determined that the two methods do not correlate at all. This is most likely a result of the silver interacting with the media in the zone of inhibition test, thus invalidating the results of this test. We therefore conclude that zone of inhibition data generated for silver-containing dressings is of little value when assessing antimicrobial efficacy and that time-kill assays are of greater use.
Gallant-Behm
Corrie L
CL
Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada.
Yin
Hua Q
HQ
Liu
Shijie
S
Heggers
John P
JP
Langford
Rita E
RE
Olson
Merle E
ME
Hart
David A
DA
Burrell
Robert E
RE
D000287:Administration, Topical; D000891:Anti-Infective Agents, Local / Q000008:administration & dosage*; D001424:Bacterial Infections / Q000150:complications / Q000188:drug therapy*; D001458:Bandages; D066298:In Vitro Techniques; D008826:Microbial Sensitivity Tests / Q000379:methods; D009181:Mycoses / Q000150:complications / Q000188:drug therapy*; D018030:Silver Compounds / Q000008:administration & dosage*; D014946:Wound Infection / Q000188:drug therapy* / Q000209:etiology
D000891:Anti-Infective Agents, Local; D018030:Silver Compounds