Approximately six months previously a 61-year-old woman had seen her dentist about pain in
the left side of her mouth Five teeth were extracted. Several abscesses, which developed after
the extraction, were incised and drained. Several short courses of antimicrobial therapy gave
temporary improvement. Approximately one month prior to admission, a mass developed in
the left parotid area. A needle aspirate of the mass was submitted for gram stain and culture.
Yellowish particles were present in the aspirate. The specimen was cultured aerobically and
anaerobically. After three days of incubation, small colonies of gram negative coccobacilli were
present on the blood and chocolate agar plates. The characteristics of the gram negative
coccobacilli are as follows:
MacConkey agar: No growth
Oxidase: Negative
Catalase: Weak Positive
Kligler's: Weak acid in butt
Motility: Negative
Nitrate: Reduced
Indole: Negative
After ten days incubation, the anaerobe blood agar plate had colonies. A gram-stained smear
of the colonies is shown in the picture below:
QUESTIONS:
1. Identify the aerobic gram negative organism. What is the expected colony morphology of
this organism?
2. Give the presumptive identification of the anaerobic organism. What is the expected
colony morphology of this organism?
3. What term is used to describe the yellow particles present in the clinical specimen? Of
what do they consist?