Chapter 11: Interactions between Microbes and Humans (Down to Step one of beocming established - portals of entry)

Our resident microbiota does what and doesn’t cause what? What is the definition of infection? Does colonization equal infection?

• For the most part, our resident microbiota colonize us for the long term and do not cause disease

• Infection: successful colonization by pathogens and microbes get past host defenses, enter tissues, and multiply

• Colonization doesn’t equal infection

What is a disease? What is an infectious disease? Are all diseases infectious?

• Disease: deviation from a healthy status that results when cumulative effects of infection damage or disrupt tissues and organs (More severe than infection)

• Infectious disease: a pathologic state caused directly by microorganisms or their products

• Not all diseases are infectious

What is a pathogen? What is pathogenicity?

• Pathogen: a microbe whose relationship with its host is parasitic and results in infection and disease

• Pathogenicity: an organism’s potential/ability to cause disease

What are the two types of pathogens? And what are their definitions?

• True/Primary pathogens: capable of causing disease in healthy persons with normal immune defenses

• Opportunistic pathogens: cause disease when the host’s defenses are compromised or when the pathogens become established in a part of the body that is not natural to them (ex: immunocompromised patients)

What is virulence and it’s a degree of what? Virulence of a microbe is determined by what?

1. Virulence:

• Relative severity of a disease caused by a particular microbe

• Degree/measure of pathogenicity

2. Virulence of a microbe is determined by its ability to:

• Establish itself in a host

• Cause damage

What is a virulence factor? What does increased virulence cause?

Virulence factor: any characteristic, behavior, product, or structure of the microbe that contributes to its ability to establish itself in the host and cause damage

• Increased virulence causes increased severity and increased capability of entering host

Majority of infections are what with what type of contributions? Influenza infection frequently leads to?

• Majority of infections are polymicrobial, with contributions from more than one microbe

• Influenza infection frequently leads to pneumonia (ex: fluid sometimes ends up in lungs causing pneumonia)

What are the 5 steps Involved when a Microbe Causes Disease in a Host? What steps are establishing an infection vs the actual disease?

1. Pending a portal of entry

2. Attaching firmly and negotiating the microbiome (attach to appropriate host tissue or they’re eliminated)

3. Surviving host defenses (grow & survive)

4. Causing damage (disease)

5. Exiting host

• 1-3 are establishing infection and 4 & 5 are the disease