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Questions and Answers
Which virulence factor primarily helps bacteria resist phagocytosis?
Which virulence factor primarily helps bacteria resist phagocytosis?
What is the role of collagenase in bacterial virulence?
What is the role of collagenase in bacterial virulence?
Which of the following statements about bacterial exotoxins is true?
Which of the following statements about bacterial exotoxins is true?
Which enzyme produced by some microbes can hydrolyze the beta-lactam ring of antibiotics?
Which enzyme produced by some microbes can hydrolyze the beta-lactam ring of antibiotics?
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What makes bacterial endotoxins less antigenic than exotoxins?
What makes bacterial endotoxins less antigenic than exotoxins?
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Which pigment is associated with the bacterium Pseudomonas aeruginosa?
Which pigment is associated with the bacterium Pseudomonas aeruginosa?
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What is the primary function of fimbriae in bacterial pathogenicity?
What is the primary function of fimbriae in bacterial pathogenicity?
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Which enzyme helps bacteria neutralize acidic conditions in urine and stomach?
Which enzyme helps bacteria neutralize acidic conditions in urine and stomach?
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What characteristic distinguishes exotoxins from endotoxins?
What characteristic distinguishes exotoxins from endotoxins?
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Which of the following bacterial enzymes assists in the coagulation of plasma?
Which of the following bacterial enzymes assists in the coagulation of plasma?
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Study Notes
Bacterial Growth (2) - Bacterial Genetics and Virulence Factors
- Bacterial virulence factors are cellular structures, enzymes, and toxins that enhance bacterial pathogenicity.
- Key virulence factors include the capsule, fimbriae (pili), teichoic acid, enzymes, bacterial toxins (exotoxins/endotoxins), and pigments.
1- Bacterial Virulence
- Capsule: Resist phagocytosis and hydrolytic enzymes (lysozymes) that break down cell walls. Adheres to host cells.
- Fimbriae (Pili): Adheres to host cell surfaces.
- Teichoic Acid (Gram-positive bacteria): Adheres to host cell surfaces.
4- Microbial Enzymes
- Collagenase: Aids microbial invasion by degrading the extracellular matrix (collagen).
- Urease: Neutralizes acidic pH in urine and stomach.
- Hemolysin: Degrades red blood cells (RBCs) and releases hemoglobin.
- Haemagglutinin and coagulase enzyme: Agglutinates RBCs and coagulates plasma; the microbe can escape humoral immunity.
- Catalase: Breaks down hydrogen peroxide (H₂O₂) into water (H₂O) and oxygen (O₂).
5- Bacterial Toxins
- Exotoxins: Produced by Gram-positive and Gram-negative bacteria, diffuse outside the bacteria, are proteins, heat-labile, and toxoids formed for vaccine use.
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Endotoxins: Produced by Gram-negative bacteria, part of the cell wall, are lipopolysaccharides, heat-stable, have no effect from formalin treatment, and are less antigenic.
- Examples: Clostridium botulinum toxin and Clostridium tetani toxin.
6- Bacterial Pigments
- Exopigments: Diffuse into the surrounding medium, an example is bluish-green pigments from Pseudomonas aeruginosa.
- Endopigments: Stay within the cell.
2- Bacterial Genetics
- Bacterial Chromosome: A single circular, double-stranded DNA.
- Plasmids: Additional genetic material outside the chromosome; circular, supercoiled DNA carrying important genes like those for resistance.
Mechanisms of Gene Transfer
- Conjugation: Transfer of plasmids from one bacterial cell to another via sex pili (in gram-negative bacteria).
- Transduction: Transfer of genetic material through a virus (bacteriophage).
- Transformation: Uptake of DNA fragments from a lysed donor bacterial cell by a recipient cell.
Additional Information
- Corynebacterium diphtheriae: This bacterium causes diphtheria and produces diphtheria toxin. The gene encoding the toxin is transferred to other bacteria via a bacteriophage (transduction).
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Description
Explore the critical role of bacterial virulence factors in pathogenicity. This quiz covers key concepts including capsules, fimbriae, teichoic acid, and microbial enzymes that enhance bacterial invasion and survival. Test your knowledge on how these factors contribute to bacterial infections.
