Microbial Mechanisms of Pathogenicity

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Lectures

Key Terms

Multiple ChoiceQuestions

Questions

Updated 19/02/01

They say that what you don’t know won’t hurt you Some of us haven’t felt a twitch of pain in years Fletcher Knebel
	Early Microscopists

Who Am I? Trained as a zoologist, I coined the term phagocyte after observing the response of starfish larvae to rose thorns. I late showed that white blood cells are phagocytic

	Microbial Mechanisms of Pathogenicity
	Mechanisms of Pathogencitiy HBF Lecture
	Baron Medical Microbiology Chapter 1 Immunology Overview		Brock 9th Ed Biology of Microorganisms Chapt 20 Concepts of Immunology Chap 21: Clinical and Diagnostic Microbiology and Immunology
	Tortora: Microbiology An Introduction Chapt 15: Microbial mechanisms of Pathogenicity		Jacquelyn Black 4th Ed Microbiology: Principles & Explorations Chap 16: Nonspecific Host Defenses
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Pathogenic Mechanisms

KEY TERMS:
Pathogenicity	virulence	portal of entry	parenteral route
LD₅₀	Minimal effective dose	ID₅₀	Adherence
Adhesin	ligand	receptor	M protein
coagulase	hemolysin	cytolysin	kinase
hyaluronidase	collagenase	invasin	toxingencity
toxemia	exotoxin	endotoxin	enterotoxin
antitoxin	toxoid	lipid A	shock
septic shock	endotoxic shock	Limulus ameoebocyte lysate	LAL
lysogeny	lysogenic conversion	cytopathic effects	inclusion bodies
syncytium	aflatoxin	saxitoxin	red tide
amanitin

SHORT ANSWER QUESTIONS

Identify the principal portals of entry of microbes into the huma body.
Compare the LD₅₀ with the Minimal Lethal Dose and discuss the advantages and disadvantages of each.
Use specific examples to explain how microbes adhere to host cells.
Explain how capsules and cell wall components contribute to pathogencity.
Contrast the nature and effects of exotoxins and endotoxins.
Describe the LAL assay and discuss its importance
What are the three principal types of exotoxins based on their modes of action? Describe these modes of action.
Use specific examples to describe the roles of plasmids and lysogeny in pathogenicity.
List 5 different cytopathic effects induced by viruses
Compare pathogenicity with virulence
The LD₅₀ of botulinum toxin is 0.000025 ug.The LD₅₀ of Salmonella toxin is 200 ug. Which of these is the more potent toxin? How can you tell from the LD₅₀ values?
When injected into rats, the ID₅₀ for Salmonella typhimurium is 10⁶ cells. If sulfonamides are injected with the slamonellae, the ID₅₀ is 35 cells. Explain the change in the ID₅₀ value.
Water containing Pseudomonas was sterilized and used to wash cardiac catheters. Three patients undergoing cardiac catheterization developed fever, chills and hypotension. The water and the catheters were sterile. Why did the patients show these reactions?
On July 8, a woman was given an antibiotic for presumptive simusitis. However, her condition worsened and she was unable to eat for 4 days becauses of severe pain and tighness of the jaw. On July 12 she was admitted to a hosptial with sever facial spasms. She reported that on July 5 she had incurred a puncture wound at the base of her big toe; she cleaned the wound but did not seek medical attention. What caused her symptoms? Was her condition due to an infection or an intoxication? Can she transmit this condition to another person?