In vitro fungistatic and fungicidal activities of silver sulfadiazine and natamycin on pathogenic fungi isolated from horses with keratomycosis.
OBJECTIVE
To evaluate the in vitro antifungal properties of silver sulfadiazine (SSD) and natamycin against filamentous fungi isolated from eyes of horses with keratomycosis.


METHODS
Filamentous fungal isolates obtained from eyes of keratomycosis-affected horses.


METHODS
Fungal culture of ocular samples yielded 6 Fusarium spp; 7 Aspergillus spp; and 1 isolate each of Curvularia, Scopulariopsis, Penicillium, and Chrysosporium. For each fungal isolate, minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of SSD and natamycin were determined.


RESULTS
For all 17 fungal isolates, SSD MIC distribution ranged from < or = 1 to > 64 microg/mL; MIC50 and MIC90 (MICs at which 50% and 90% of organisms were inhibited) were 4 and 32 microg/mL, respectively. The SSD MFC distribution for all isolates was < or = 1 to > 64 microg/mL; MFC50 and MFC90 (MFCs at which 50% and 90% of organisms were killed) were 8 and > 64 microg/mL, respectively. For all fungal isolates, natamycin MIC distribution ranged from 256 to > 1,000 microg/mL; MIC50 and MIC90 were 512 and > 1,000 microg/mL, respectively. The natamycin MFC distribution for all isolates ranged from 512 to > 1,000 microg/mL; MFC(50) and MFC(90) were each > 1,000 microg/mL.


CONCLUSIONS
These in vitro data suggest that SSD is fungicidal against the fungal isolates that were obtained from eyes of horses with keratomycosis and that natamycin is fungicidal against some of the isolates at the drug concentrations evaluated. Silver sulfadiazine may be a therapeutic option for equine keratomycosis.
Betbeze
Caroline M
CM
Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA.
Wu
Ching Ching
CC
Krohne
Sheryl G
SG
Stiles
Jean
J
D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D015821:Eye Infections, Fungal / Q000382:microbiology / Q000662:veterinary*; D005658:Fungi / Q000187:drug effects* / Q000302:isolation & purification; D006734:Horse Diseases / Q000382:microbiology*; D006736:Horses / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D010866:Natamycin / Q000494:pharmacology*; D012837:Silver Sulfadiazine / Q000494:pharmacology*
D000935:Antifungal Agents; D010866:Natamycin; D012837:Silver Sulfadiazine