Infectious Diseases Plate Rounds 9-13-23.pptx

1. Plate Round Discussion 9/13/23
• Case 1:Listeria monocytogenes bacteremia
• Case 2:Aeromonas sobria
• Case 2: Pneumocystis organism
• Case 3: Histo and CMV colonic mass biopsy GMS stain

2. Listeria
Monocytogenes
• Listeriosis is a serious infection usually caused by eating food contaminated with
the bacterium Listeria monocytogenes especially pregnant women and their new
born.
• People with normal immune systems rarely develop invasive infection.
• Unlike most foodborne pathogens, it can grow at standard refrigerator temperature
(40°F), which makes it a particular problem in ready-to-eat foods that are not
cooked before eating.
• It is widespread in the environment and can be isolated from soil, water, and
decaying vegetation.
• It is a hardy organism that can withstand a wide range of conditions including
freezing, drying, heat, and relatively high levels of acid, salinity, and alcohol.

3. Diagnostic
testing
• Facultatively anaerobic, rod-
shaped, gram-positive bacterium
• Looks like Group B strep but is a
dry, GPB, and catalase pos
• Camp test positive
• Oxidase neg, indole neg, esculin
pos

4. Aeromonas
Sobria
• Commonly isolated from mucosal
surfaces and internal organs of healthy
fish and typical environmental species
frequently recovered from diseased
fish (especially trout).
• Common inhabitants of fresh and
brackish water in the United States
• Increasingly recognized as causes
of gastroenteritis in both children
and adults. Also causes wound
infections, septicemia and lung
infections.

5. Diagnostic Testing
• Organisms are gram-negative, beta
hemolysis, facultatively anaerobic bacilli
with a single polar flagella
• Oxidase=pos, Catalase=pos, Indole=pos
• Molecular techniques can be used to
determine species type