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MHD Block3: Gram Positive Rods and Aerobic Actinomycetes > Gram Positive Rods- Listeria and Bacillus > Flashcards

Gram Positive Rods- Listeria and Bacillus Flashcards

1
Q

Which bacteria are gram positive rods?

A 
Bacillus
Lsiteria
Erysipelothrix
Corynebacteria
Arcanobacterium
Lactobacillus
Nocardia
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2
Q

What are the characteristics of Bacillus

A

Spore Forming
Gram Positive Rod
Aerobic preference
Motile (except B.Anthracis)

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3
Q

What are characteristics of Bacillus Anthracis

A

Cat A biothreat Agent

Causes Anthrax via ingestion/inhalation

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4
Q

What is a category A pathogen?

A

Agents that pose high risk to national security adn public health due to:
Easy dissemination/transmission from person to person
High Mortality rates
Public panic and social disruption
REquires special action for public health preparedness

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5
Q

Which bacteria are Cat A priority pathogens?

A

B.Anthracis
C.Botulinum toxin
Yersinia Pestis (plague)
Francisella Tularensis

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6
Q

How does anthrax infection look cutaneously?

A

Painless papule
Ulcer surrounded by vesicles
Necrotic Eschar in center

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7
Q

What are the sx of GI anthrax

A

Upper GI: Ulcers in mouth and esophagus
Lower GI: Terminal ileum, nausea, vomiting, blood diarrhea
100% mortality

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8
Q

What is the pathogenesis of inhaled anthrax?

A

Prolonged latent period
Initial: nonspecific sx (fever, cough, SOB, HA, vomiting, etc)
Second Stage: rapidly worsenng fever, edema and enlargement of mediastinal lymph nodes (widened mediastinum on chest X ray)

Meningeal sx in 50% of patients
Shock and death within 3 days if no treatment

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9
Q

What is the pathogenesis of B.Anthracis?

A

Capsule inhibits phaogcytosis and allows multiplicaiton
Edema Toxin: fluid accumulation
Lethal Toxin: Stimulate macrophages to secrete TNF and IL-1b
Protective AG: binds to cell surface receptors and enables ET and LT to enter cell

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10
Q

How is Anthrax diagnosed?

A

Culture from skin, blood, sputum, or CSF
Gram + Box car shaped bacilli
Biochemical: Neg Motility, Non-hemolytic
Penicillin susceptible

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11
Q

How is Anthrax treated?

A

Cipro, Doxycycline, Penicillin (if susceptible)

Prophylaxis: cipro and doxy for inhalation 60 days

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12
Q

Where is Bacillus Cereus found?

A

Food poisoning (reheated fried rice?)

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13
Q

Describe Listeria

A

Non spore forming
Gram positive Rod
Found in animals, environment, refrigerated foods

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14
Q

How do people get listeria monocytogenes infection?

A

Undercooked/Unpasteurized food- soft cheeses,, veggies, cold cuts

Can grow at refrigerator temp

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15
Q

Describe the pathogenesis of Listeria

A

Invade epithelial cells, M cells and macrophages via Internalin protein -> vacuole -> produce LISTERIOLYSIN and PHOSPHOLIPASE -> escape phagosome -> ActA gene -> moves host cell actin to allow transfer to adjacent cells without exposure to immune system

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16
Q

What kind of immunity is important for listeria infection?

A

Cell Mediated Immunity

Humoral immunity unimportant as bacteria move within cells and avoid Ab-mediated clearance

Pt deficient in cell mediated immunity are susceptible ot severe infections

17
Q

What happens to neonates with listeria infections?

A

Early Onset Disease: transplacentally in utero -> disseminated abscesses and granulomas in organs =>usually fatal

Late Onset Disease: Acquired at or shortly after birth -> meningitis with septicemia

18
Q

What happens to elderly people with listeria infeciton?

A

Influenza like illness w/ or w/out gastroenteritis

19
Q

What happnes to pregnant women or pts with cell mediated immune defects with listeria infections?

A

Bacteremia

Disseminated disease w/ hypotension and meningitis

20
Q

How does listeria look in culture?

A

Cultures: Blood, CSF, fluids
B-Hemolytic
Gram Positive Rods

21
Q

What are the biochemical properties of listeria?

A

Catalase positive
Tumbling motility
Non-motile at 37 degC
Umbrella motiliy on motility agar

22
Q 
Growth on BAP:
Small, gray-white colonies
Narrow zone of β-hemolysis
Looks like Streptococcus
Except Catalase +
What is the most likely identification of this bacteria?
A. Streptococcus agalactiae
B. Arcanobacterium
hemolyticum
C. Staphylococcus aureus
D. Bacillus anthracis
E. Listeria moncytogenes
A

E

Strep is catalase negative

23
Q

How is Listeria treated?

A

Penicillin
Ampicillin +/- Gentamicin

Resistant to cephalosporins

MHD Block3: Gram Positive Rods and Aerobic Actinomycetes (2 decks)

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