Flashcards in Microbiology 5: When humans and microorgansims come together Deck (18):
What is infection?
Successful multiplication of a microorganism within or on a host
What is colonization?
Persistence in a particular body site of microorganisms that do NOT cause disease
How do we differentiate infection from infectious disease?
An infection that produces signs and symptoms
Why is the burden of infectious disease lower in developed countries?
In developed countries we have taken steps to control infectious disease:
-Low density of living
-Proper handling of food -
Why are infectious disease more common in developing countries?
*High density of living *Improper handling of food *Inadequate vaccination
What are pathogens?
Microorganisms that cause infectious disease.
What are the two types of pathogens?
-Principal pathogen (regularly causes disease)
-Opportunistic pathogen (rarely causes disease)
What are the host defense mechanisms?
What is the role of mucus?
Ø Lysozyme Kills Gram-positive bacteria
Ø Lactoferrin Removes source of iron required for bacterial growth
Ø Antibodies- IgA complexes with bacteria Taken up by phagocytic cells
What is the purpose of nasal hair, cough response, and saliva?
Traps microorganisms, expels microorganisms, flushes microorganisms out of mouth and is antibacterial (lysosomes)
What are the benefits of normal flora of the GIT?
-Competes with pathogens for nutrients
-Excludes pathogens by inhabiting specific sites
-Metabolic processes of the normal flora (changes in pH)
-Produce toxic metabolites
What is virulence?
A measure of pathogenicity, or the ability of an organism to cause disease
What is a virulence factor?
A microbial factors or strategy that contributes to virulence
How can bacteria adhere?
Using pili or fimbrae (clotting factor with staph aureus, and binding proteins with pyogenes)
What permits motility of bacteria?
Flagella and chemotaxis
What is the benefit of invading host cells?
Evades host immune system, and antibiotics
What is steptococuus pneumoniae's virulence factor?
It has a capsule that prevents binding by complement and phagocytosis.