14 Questions
Neisseria meningitidis is a Gram-positive bacterium.
False
The serotype of Neisseria meningitidis refers to the polysaccharide capsule.
False
Neisseria gonorrhoeae is a fastidious bacterium that can survive outside of neutrophils.
False
Neisseria meningitidis is aerobic and oxidase negative.
False
Pili are a virulence factor of Neisseria meningitidis that enhances resistance to phagocytosis and attachment to host cells.
True
College students are not a high-risk group for meningitis.
False
Neisseria gonorrhoeae is transmitted through casual contact.
False
The capsule of Neisseria meningitidis is antigenically homogeneous and cannot change to avoid host defenses.
False
Corynebacterium species are commonly found in the human microbiota of the skin, upper respiratory tract, GI tract, and Urogenital tract.
True
Corynebacterium diphtheriae is a Gram-negative, spore-forming bacillus.
False
The diphtheria toxin gene is encoded by the bacterium itself.
False
Corynebacterium diphtheriae causes disease in the late stage by inducing muscle weakness and edema.
True
The lethal dose of diphtheria toxin for humans is approximately 1 μg of toxin per kg of body weight.
False
Diphtheria toxin blocks DNA synthesis.
False
Study Notes
Neisseria Genus
- Genus: Neisseria
- Species: Gonorrhoeae and meningitidis
Characteristics
- Gram negative cocci (Diplococci)
- Non spore forming and non motile
- Oxidase positive
- Intracellular, usually found in polymorphonuclear cells
- Aerobic
Neisseria meningitidis
- Virulence factors:
- Capsule: antigenically heterogeneous and capable of changing to avoid host defenses
- Pili (Fimbriae): enhance attachment to host cells and resistance to phagocytosis
- Toxin: endotoxin lipid A part of lipopolysaccharide
- Enzyme: IgA protease
Meningitis
- Inflammation of the membranes of the brain or spinal cord
- High risk groups:
- Infancy
- Elderly
- Immunocompromised
- Head trauma
- Neural surgery
- College students
- Military recruits
Neisseria gonorrhoeae
- Gram-negative
- Oxidase positive
- Aerobic and survives within neutrophils
- Fastidious
- Coccal (diplococcal arrangement)
- Humans are the only natural hosts for gonococcus, transmitted through sexual intercourse
Corynebacterium
- Genus of bacteria that are Gram-positive, aerobic, non-capsulated, and non-spore-forming bacilli.
- Found in skin, upper respiratory tract, GI tract, and Urogenital tract of humans as part of human microbiota.
- Also occur naturally in soil, water, plants, and food products.
Corynebacterium diphtheriae
- Rod-shaped, Gram-positive, non-spore-forming, and non-motile bacterium.
- Characterized by granules within rods stained with aniline dyes.
- Causes the disease diphtheria.
Pathogenesis of Diphtheria
- Early stage symptoms: sore throat, low fever, muscle weakness, edema, and pseudomembranous material in the upper respiratory tract.
- Late stage symptoms: airway obstruction, breathing difficulty, and shock.
Virulence Factors: Diphtheria Toxin
- Exotoxin secreted by Corynebacterium diphtheriae.
- Toxin gene is encoded by a bacteriophage.
- Extremely potent, with a lethal dose of approximately 0.1 μg of toxin per kg of body weight.
- Causes death through necrosis of the heart and liver.
- Blocks protein synthesis.
This quiz covers the characteristics of the Neisseria genus, specifically Neisseria gonorrhoeae and meningitidis, including their gram stain, motility, and virulence factors.
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