Case #3:

Clinical Presentation:
A 64 year old diabetic man presents with severe frontal headache and left eye pain, 12 hours after vitrectomy and lens implantation for corneal cataracts.

Clinical Diagnoses:
Post-operative bacterial endopthalmitis
presumed Staphylococcus or Streptococcus
less likely: Pseudomonas, Proteus

Microscopic Examination of Anterior Chamber Aspirate:
Gram stain (Case 3 Image 1): numerous variably shaped gram-positive bacilli. Note the coccoid retinal pigment in the background and the absence of leukocytes.

Histologic Section of intraocular contents:
Gram stain (Case 3 Image 2): enormous numbers of gram-positive bacilli

Culture Plates (Case 3 Image 3):
24 hour growth of Bacillus cereus on sheep blood agar showing colonies surrounded by large double zone of beta (clear) hemolysis.

Discussion:
Wet preparation of the direct specimen demonstrated motile rods. This allows immediate differentiation from the gas-gangrene bacillus, Clostridium perfringens, which is non-motile. Additionally, B. cereus has two enterotoxins and can cause food poisoning by germination of spores in reheated rice.