chapter
chapter 3 Diagnostic Culture and Identification (Bacterial and Fungal)........
Identification (Bacterial
and Fungal)
DEFINITION/OVERVIEW
Culturing dermatologic lesions for dermatophytes is always appropriate.
Samples for culture should be submitted if fungal organisms (non-Malasseziaspp.)
are identified in epidermal or aural exudates.
Bacterial culture and sensitivity testing is often not required for the treatment of rou-
tine bacterial folliculitis in the dog.
Bacterial culture and sensitivity is indicated when cases fail to respond to an appro-
priate antibiotic choice.
Bacterial culture and sensitivity is appropriate if rod bacteria are identified in epider-
mal or aural exudates.
DERMATOPHYTE CULTURE AND IDENTIFICATION
Culture Media
Dermatophyte test medium (DTM): Sabouraud’s dextrose agar modified by the addi-
tion of antimicrobials to discourage the growth of nondermatophytes, and phenol red
as a pH indicator.
Sabouraud’s dextrose agar or rapid sporulating medium (RSM): agars used to encour-
age development of conidia for dermatophyte identification.
DTM delays the development of conidia; products with a combination of agars are
recommended.
Media plates allow better access for inoculation of samples than small glass bottles.
Incubate cultures at room temperature (75–80◦F), kept away from ultraviolet light,
and prevented from desiccation by placing a small cup of water in the incubator. A
small food storage container can act as an informal incubator.
Sample Collection
Hair pluck (Figures 3.1, 3.2):
Remove hairs at the periphery of lesions with sterile forceps
Selection of hairs by Wood’s lamp may increase success
Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Dermatology, Third Edition.
Karen Helton Rhodes and Alexander H. Werner.
©2018 John Wiley & Sons, Inc. Published 2018 by John Wiley & Sons, Inc.
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