Principles of Pathogenesis and Pathogenic Microorganisms

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Questions and Answers

What defines a microorganism as a pathogen?

Its tendency to cause disease in immunocompromised patients

Its ability to cause disease in healthy persons with normal immune defenses (correct)

Its origin from a source outside the body

Its existence as part of the body's normal flora

Which type of pathogens rarely cause disease in immunocompetent people but can cause serious infections in immunocompromised patients?

Exogenous agents

Endogenous agents

True pathogens

Opportunistic pathogens (correct)

What is the 50% lethal dose (LD50) a measure of?

The number of organisms needed to cause mild illness

The number of organisms needed to kill half the hosts (correct)

The number of organisms needed to infect the host

The number of organisms needed to cause any form of disease

What are virulence factors responsible for?

Infecting or damaging host tissues Signup and view all the answers

Which type of toxin can cause disease even in the absence of the microorganism itself?

Exotoxins Signup and view all the answers

Which component of AB exotoxins is responsible for the toxic effects?

A subunit Signup and view all the answers

Which disease is caused by an exotoxin that prevents the release of inhibitory neurotransmitter glycine?

Tetanus Signup and view all the answers

Which disease is caused by an exotoxin that triggers cAMP production and causes severe diarrhea and dehydration if left untreated?

Cholera Signup and view all the answers

What type of exotoxins can make protein channels in the plasma membrane and kill various immune cells?

Membrane-disrupting toxins Signup and view all the answers

Which type of exotoxins stimulate a wide immune response by binding to major histocompatibility complex (MHC) class II molecules?

Superantigens Signup and view all the answers

Which type of bacteria most commonly secretes exotoxins?

Gram-negative bacteria Signup and view all the answers

What is the primary function of the B subunit in AB exotoxins?

To bind to specific target cells Signup and view all the answers

Which of the following refers to the ability of bacteria to spread to adjacent tissues through active or passive means?

Invasiveness Signup and view all the answers

What are the critical determinants in overpowering the host during infectious diseases?

The number of organisms and their virulence Signup and view all the answers

What is the term for specific toxins produced by bacteria, which can have local or systemic effects?

Toxicity Signup and view all the answers

Which mechanism involves the production of capsules, biofilms, toxins, degradative enzymes, and resistance to antibiotics by bacteria?

Bacterial virulence Signup and view all the answers

What are exoenzymes produced by pathogens that enable them to invade host cells and deeper tissues?

Glycohydrolases Signup and view all the answers

Which type of pathogens can cause disease through invasiveness, toxicity, and immunopathology?

Bacteria Signup and view all the answers

What is the term for the ability of pathogens to escape from the body's immune system?

Immunosuppression Signup and view all the answers

'Exoenzymes' are primarily involved in which bacterial function?

'Invasiveness' Signup and view all the answers

Study Notes

Staphylococcus aureus virulence factors include molecules synthesized by the bacteria or acquired from the environment
Virulence factors enable the bacteria to cause damage to the host through various functions: colonization, immune escape, immunosuppression, cellular entry and exit, and nutrient extraction
People get infectious diseases when the balance between the organism and the host shifts in favor of the organism
Critical determinants in overpowering the host are the number of organisms and their virulence
Pathogens can enter the body through various portals of entry, including mucous membranes, respiratory and gastro-intestinal tracts, genitourinary tract, conjunctiva, skin, and parenteral route
Transmission of infectious diseases can occur through fecal-oral contact, wounds, burns, contact with animals or humans, and vectors
Bacterial virulence mechanisms include the production of capsules, biofilms, toxins, degradative enzymes, and resistance to antibiotics
Pathogens can cause disease through toxicity, invasiveness, and immunopathology
Toxicity refers to specific toxins produced by bacteria, which can have local or systemic effects
Invasiveness involves the ability of bacteria to spread to adjacent tissues through active or passive means, and the production of specific products and/or enzymes that promote spreading
Exoenzymes are extracellular enzymes produced by pathogens that enable them to invade host cells and deeper tissues, and have a wide variety of targets
Different classes of exoenzymes include glycohydrolases, nucleases, and proteases, each with specific targets
Staphylococcus aureus is an example of a bacterium that causes systemic infections and is able to proliferate, disseminate, and destroy tissues, and produces various toxins and enzymes for virulence.

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Description

Test your knowledge on the principles of pathogenesis and the characteristics of pathogenic microorganisms. Learn about true pathogens and opportunistic pathogens, and their ability to cause disease in humans with different levels of immune defenses.