Gram Positive Rods- Listeria and Bacillus Flashcards
Which bacteria are gram positive rods?
Bacillus Lsiteria Erysipelothrix Corynebacteria Arcanobacterium Lactobacillus Nocardia
What are the characteristics of Bacillus
Spore Forming
Gram Positive Rod
Aerobic preference
Motile (except B.Anthracis)
What are characteristics of Bacillus Anthracis
Cat A biothreat Agent
Causes Anthrax via ingestion/inhalation
What is a category A pathogen?
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
Which bacteria are Cat A priority pathogens?
B.Anthracis
C.Botulinum toxin
Yersinia Pestis (plague)
Francisella Tularensis
How does anthrax infection look cutaneously?
Painless papule
Ulcer surrounded by vesicles
Necrotic Eschar in center
What are the sx of GI anthrax
Upper GI: Ulcers in mouth and esophagus
Lower GI: Terminal ileum, nausea, vomiting, blood diarrhea
100% mortality
What is the pathogenesis of inhaled anthrax?
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
What is the pathogenesis of B.Anthracis?
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
How is Anthrax diagnosed?
Culture from skin, blood, sputum, or CSF
Gram + Box car shaped bacilli
Biochemical: Neg Motility, Non-hemolytic
Penicillin susceptible
How is Anthrax treated?
Cipro, Doxycycline, Penicillin (if susceptible)
Prophylaxis: cipro and doxy for inhalation 60 days
Where is Bacillus Cereus found?
Food poisoning (reheated fried rice?)
Describe Listeria
Non spore forming
Gram positive Rod
Found in animals, environment, refrigerated foods
How do people get listeria monocytogenes infection?
Undercooked/Unpasteurized food- soft cheeses,, veggies, cold cuts
Can grow at refrigerator temp
Describe the pathogenesis of Listeria
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
What kind of immunity is important for listeria infection?
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
What happens to neonates with listeria infections?
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
What happens to elderly people with listeria infeciton?
Influenza like illness w/ or w/out gastroenteritis
What happnes to pregnant women or pts with cell mediated immune defects with listeria infections?
Bacteremia
Disseminated disease w/ hypotension and meningitis
How does listeria look in culture?
Cultures: Blood, CSF, fluids
B-Hemolytic
Gram Positive Rods
What are the biochemical properties of listeria?
Catalase positive
Tumbling motility
Non-motile at 37 degC
Umbrella motiliy on motility agar
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
E
Strep is catalase negative
How is Listeria treated?
Penicillin
Ampicillin +/- Gentamicin
Resistant to cephalosporins
