Methods: The efficacy of CN was evaluated against 14 mold (3 Aspergillus spp., 2 Fusarium spp., 5 different mucormycetes, 2 Bipolaris spp., 1 Alternaria spp., 1 Exophiala spp.) and 21 Candida spp. isolates collected as part of the Trauma Infectious Disease Outcomes Study. Fungicidal activity of various concentrations of CN (2.2%, 1%, 0.5% and 0.2%) was determined using an established time-kill assay. Standard conidia/cell suspensions were prepared according to Clinical and Laboratory Standards Institute guidelines and then exposed to the CN solutions for 24 hours. At different times (0, 5, 15, 30 min, 1, 1.5, 3, 6, 12, and 24 hours) aliquots were plated and incubated at 35ºC. Colony forming unit (CFU) counts were determined after 24 hours incubation or after an appropriate time for slow growing molds.
Results: All mold isolates had persistent growth at 24 hours with most having no significant change in colony counts over the 24-hour period. The only exception was Mucor circinelloides, which appeared to have a time-dependent reduction in CFUs at 24 hours for all CN concentrations. Exophiala did not grow as well in CN solutions compared to the control (mean 65 vs. 28.2 CFUs with a difference of mean 37.4 CFUs, p = 0.0001), but this was not time or concentration-dependent. All yeast species showed a time-dependent killing after 6-12 hours.
Conclusion: CN demonstrated time-dependent killing of the yeasts. However, very little activity was observed against the tested molds. Since CN is often used in combination with SS there might be a synergistic effect against molds. Further research will evaluate higher concentrations of CN and its toxicity for cells and tissue.
D. Blyth, None
K. S. Akers, None
D. R. Tribble, None
K. Mende, None