Case 307 -- Dog Bites

Contributed by Leena Lourduraj, MD, Eileen Driscoll, MT(ASCP), and A. William Pasculle, ScD
Published on line in May 2002


The patient is a 56-year old white male with a past medical history significant for lymphoma (now in remission). He is a health care worker who presented to the emergency room because of a dog bite on the left side of his face and along the left index finger. The dog belonged to the patient and was up to date with all its shots.

On physical examination the patient was afebrile with a respiratory rate of 18/minute and blood pressure of 122/80 mmHg. Examination of the cardiovascular system, respiratory system, central nervous system and gastrointestinal system was normal. On local examination of the dog bite wound on his face it was noted that he had a laceration on the lateral aspect of the left side with associated moderate soft tissue swelling and ecchymosis. The bite on his left index finger was a 1 mm wound on the distal phalanx. There was no erythema or soft tissue swelling noted around it.

Gram stain of the wound on the left cheek showed rare white blood cells with no organisms present.

Wound culture was performed on the laceration on the left cheek.


Fig. 1  Aerobic culture on blood agar medium of the dog bite wound on the face showed two types of colonies of organisms. Subcultures of both the colonies were performed (see Figs. 2, 3, and 4)
Fig. 2  Subculture from the smaller colony done on blood agar showed 1-2 mm smooth gray non-hemolytic mucoid colonies. The organism did not grow on Mac-Conkey agar or EMB agar. (See biochemical tests for the smaller colonies)
Fig. 3  Subculture from the smaller colony done on chocolate agar showed 1-2 mm smooth gray white mucoid colonies.
Fig. 4  Subculture from the larger colony done on EMB showed large pale cream mucoid colonies. The organism grew well on MacConkey agar. (See biochemical tests for larger colonies)
Fig. 5  Gram stain done on the smaller colonies showed small gram-negative cocobacilli.
Fig. 6  Gram stain done on the larger colonies showed large gram negative bacilli.



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