Small Animal Dermatology, 3rd edition

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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