Infection (Bailey) Flashcards
What is the most common reason people seek treatment for infectious disease?
Oral infections
What are the six steps in the infectious disease process?
- Encounter
- Entry
- Colonization and/or invasion
- Multiplication and/or spread
- Damage
- Outcome
Does encountering an infectious microbe always result in infection?
No.
Some diseases are grown from within
Although the oral cavity and alimentary canal are inside the body, what is special about this canal?
It is connected to the outside world on both ends
What are the two major ways a pathogen will adhere to a host tissue?
- Nonspecific adherence: reversible docking
2. Specific adherence: irreversible anchoring with adhesins
Why does streptococcus mutans bind to the tooth pellicle?
It has an adhesin that specifically binds to tooth pellicle (specific adherence)
What is needed for a pathogen to colonize?
Must be able to live in the environment it wants to colonize
What are three ways bacteria take up nutrients?
- Carrier-mediated diffusion
- Phosphorylation-linked transport
- Active transport
What allows a pathogen to invade after colonization?
Specific virulence factors that allow for invasions
What are the two major mechanisms for disease multiplication?
- Lateral propagation to contiguous tissues (multiply -> spread)
- Dissemination to distant sites (spread -> multiply)
What are two major types of toxins during infection?
- Endotoxins: component of cell wall
2. Soluble substances secreted into host tissues
What makes a microbe a pathogen?
- Adheres
- Colonizes
- Replicates in given niche
- Causes damage
T/F: No microorganism is intrinsically benign or pathogenic
TRUE
T/F: Obligate anaerobes are bacteria that must have oxygen to grow.
FALSE.
Obligate anaerobes: cannot tolerate oxygen
Strict aerobes: must have oxygen to grow
Which bacteria can grow with or without oxygen?
Facultative anaerobes
What is unique about oligotrophs?
Can grow with limited nutrients
What is unique about microaerophiles?
Require some oxygen, but not a lot
What is unique about mesophiles?
Grow well in mild temperature
T/F: Gram-positive bacteria have a much thicker cell wall than gram-negative.
TRUE
What differs in the structure of the cell wall between gram-positive and gram-negative bacteria?
Murein in gram-negative contains DAP
Which type of bacteria has techoic acid at the surface?
Gram-positive
What is the importance of the techoic acid and lipopolysaccharide?
They are considered PAMPs that the immune system can recognize
What pattern recognition receptor recognizes LPS?
Toll-like receptor 4
T/F: Toll-like receptors 2 and 6 recognize teichoic acids together.
TRUE
What is the function of fimbriae (or Pili)?
Involved in attachment to other surfaces. Contain adhesins
What are the two processes by which a pathogen can enter a host?
- Through body opening (mouth, nose, etc.)
2. By piercing epithelia (insect bites, cuts, etc.)
What are the two steps of penetration into epithelial cells?
- Attachment
2. Internalization
________ size is very important in establishing an infection.
Inoculum
What are the possible outcomes of a host-parasite infection?
- Host clears out infection
- Parasite overcomes host
- Host and parasite adapt to each other
- Chronic infection - no one wins
Which has more Murien (peptidoglycan): gram positive or gram negative?
Gram positive
Which type of bacteria has an outer membrane made up of LPS?
Gram-negative
What makes up LPS?
A lipid region that faces the membrane and a polysaccharide that faces out
What part of the LPS is highly variable and antigenic?
Outer region (O-antigen)
T/F: LPS is an endotoxin.
TRUE
What are sex pili?
Connect cells during DNA transfer
What happens when a flagella rotates clockwise? Counterclockwise?
Clockwise: Tumbling
Counterclockwise: Movement
What type of movement is used by bacteria for chemotaxis?
Flagellar movement
What is special about obligate intercellular parasites?
Can only grow inside host cells
What four things must an infectious agent do to survive?
- Avoid being washed away
- Find a niche with proper nutrition
- Survive host defense
- Transfer to new host
What are some ways that an infection can damage a host?
- Cell death
- Alter metabolism
- Mechanical causes
- Host response
- Toxins
What are the structures on bacterial surface recognized by the body?
PAMPs
What are some common antigens recognized by pattern receptor proteins?
LPS - O antigen, Receptor 4
Flagella - H antigen
Capsule - K antigen
