Lecture 3 Part 3: Corynebacterium, Listeria & Bacillus Flashcards
What are the two types of spore-forming Gram-positive rods?
Aerobes – Bacillus anthracis
Anaerobes – Clostridium difficile
Which Gram-positive rod is an aerobic spore-former?
Bacillus anthracis
Which Gram-positive rod is an anaerobic spore-former?
Clostridium difficile
What are the two types of non-spore-forming Gram-positive rods?
Uniform shape – Listeria
Coryneform (irregular) shape – Corynebacterium
Which non-spore-forming Gram-positive rod has a uniform shape?
Listeria
Which non-spore-forming Gram-positive rod has an irregular (Coryneform) shape?
Corynebacterium
What is the Gram reaction and catalase activity of Corynebacterium diphtheriae?
Gram-positive (+)
Catalase-positive (+)
Is Corynebacterium diphtheriae aerobic or anaerobic?
Aerobic
What is the shape of Corynebacterium diphtheriae?
club shaped rods
Does Corynebacterium diphtheriae form spores?
it is Non-spore forming
What metabolic byproduct does Corynebacterium diphtheriae produce?
lactic acid
Where is Corynebacterium diphtheriae commonly found in humans?
on skin and nasal mucosa
What is the only known reservoir for Corynebacterium diphtheriae?
humans
true or false
Corynebacterium diphtheriae primarily causes disease in adults.
FALSE
It is primarily a pediatric disease
What is the major virulence factor of Corynebacterium diphtheriae?
Diphtheria toxin
What type of toxin is the diphtheria toxin?
exotoxin
What is the function of the B subunit of diphtheria toxin?
Binds to epidermal growth factor receptor (EGFR)
What does the A subunit of diphtheria toxin do?
Inactivates elongation factor-2 (EF-2), blocking protein synthesis
What is the sudden onset disease caused by Corynebacterium diphtheriae that affects the respiratory system?
Respiratory Diphtheria
What is the primary site of colonization for Corynebacterium diphtheriae in respiratory diphtheria?
Pharyngeal epithelium (pharyngitis)
What does the diphtheria toxin do in respiratory diphtheria?
Mediates tissue damage and causes the formation of a thick exudate (pseudomembrane)
What is the pseudomembrane in respiratory diphtheria made of?
White blood cells (WBCs), fibrin, and debris
What serious complication can the pseudomembrane in respiratory diphtheria cause?
Obstructs the airway, leading to respiratory obstruction
What is a common symptom of respiratory diphtheria due to the dislodging of epithelial cells?
severe coughing
What cardiovascular complication can occur in severe respiratory diphtheria?
acute myocarditis
How does cutaneous diphtheria present clinically?
It involves the invasion of subcutaneous tissue, resulting in the development of pustules and ulcers.
What type of bacteria is Listeria monocytogenes?
Gram-positive rods
Is Listeria monocytogenes an obligate aerobe or facultative anaerobe?
Facultative anaerobe
What kind of pathogen is Listeria monocytogenes?
intrcelluar pathogen
Does Listeria monocytogenes form spores?
it is non-spore forming
What hemolytic pattern does Listeria monocytogenes show?
Weakly β-hemolytic
How does Listeria monocytogenes typically appear under the microscope?
Often in pairs and motile at temperatures below 37°C
What unique growth properties does Listeria monocytogenes have?
It can grow at 4°C, across a wide pH range, and in high salt concentrations
How is Listeria monocytogenes primarily transmitted?
Transmitted by exposure to contaminated food
How does Listeria monocytogenes adhere to host cells?
adhere to host cell via internalins binding E-cadherin
How is Listeria monocytogenes transported into host cells?
It is transported into enterocytes or M cells.
What does Listeria monocytogenes use to burst phagolysosomes?
It uses a pore-forming cytolysin called listeriolysin O (LLO).
true or false
Listeria monocytogenes can survive in macrophages after lysis of phagolysosomes.
true
What is the result of Listeria monocytogenes infection in host cells?
Invasion, phagolysosome lysis, bacterial replication, and reinfection
What is a common clinical disease caused by Listeria monocytogenes in neonates?
Neonatal disease can include amnionitis, stillbirth, meningitis, and meningoencephalitis.
What are the symptoms of Listeria monocytogenes infection in adults?
Influenza-like illness with possible gastroenteritis.
What is a severe complication of Listeria monocytogenes infection in adults?
Bacteremia
What type of bacteria is Bacillus anthracis?
Gram(+) rods, aerobic or facultative.
Is Bacillus anthracis motile?
it is non-motile
true or false
Bacillus anthracis can survive for decades in spore form
true
What is the function of the polypeptide capsule of Bacillus anthracis?
it evades phagocytosis
Is Bacillus anthracis non-hemolytic?
yes
What is a characteristic appearance of Bacillus anthracis colonies?
They form a “Medusa head” pattern
What type of toxin does Bacillus anthracis produce?
Produces potent exotoxin complex
How is Bacillus anthracis transmitted?
Transmitted through contact with infected animals & animal products
Why is Bacillus anthracis a bioterrorism threat?
Because it can cause pulmonary anthrax
Name the 4 virulence factors for bacillus anthracis
- Edema factor (EF)
- Lethal factor (LF)
- Protective antigen (PA) – binds receptor
- glutamic acid capsule
What is the function of the protective antigen (PA) in Bacillus anthracis?
binds to host receptor
What does the edema factor (EF) and lethal factor (LF) do in Bacillus anthracis?
They increase adenylate cyclase activity and inactivate host protein production.
What is the capsule of Bacillus anthracis made of?
A glutamic acid capsule that helps it evade phagocytosis
TRUE OR FASLE
Bacillus anthracis causes hemorrhagic pneumonia.
TRUE
true or false
Skin lesions caused by Bacillus anthracis are known as malignant pustules.
TRUE
true or false
Bacillus anthracis can lead to meningitis.
TRUE
