Bacterial Pathogenesis Final Part 1 Flashcards
What is the difference between infection and disease?
Infection: pathogen colonizes the body
Disease: overt symptoms caused by infection, impairment of host
What is the difference between pathogenicity and virulence?
Pathogenicity: the ability of an organism to cause disease (genetic component)
Virulence: degree of pathology caused
What is the definition of colonization?
Becomes part of microbiota, may be transient or permanent
What is a pathogen?
Bacterium capable of harming a healthy host
What is an opportunistic pathogen?
Harms a weakened or immunocompromised host, but not healthy host
What is pathogenicity?
Ability of an organism to cause disease and represents a genetic component of the pathogen (qualitative)
What is virulence?
The degree of pathology caused by the organism (quantitative)
What is ID(50)?
Infectious dose; number of bacteria needed to cause disease in 50% of mice
What is LD(50)?
The number of bacteria needed to cause death in 50% of mice
What are virulence factors? What is an example?
Molecules produced by bacteria that enable them to establish themselves on or within a host and enhance their potential to cause disease; bacterial toxins
What are the 6 categories of virulence factors?
- Adherence factors (pili)
- Invasion factors (T3SS)
- Capsules
- Endotoxins (LPS)
- Exotoxins (secreted)
- Siderophores (iron-binding factors)
What contributes to host susceptibility?
- Stress/diet/disease
- Age
- Immune system
- Genetics
- Microbiota
What is bacterial nomenclature?
Genus species: eg., Streptococcus pyogenes (italics, and only capitalize first word)
What is Streptocuccus pyogenes known for causing?
- strep throat, tonsillitis, scarlet fever, cellulitis, rheumatic fever, necrotizing fasciitis,
What is a primary and secondary infection?
Primary: initial event, can cause disease
Secondary: opportunistic organism causes infection in weakened host
What is a sub clinical infection? What is a nosocomial infection?
Subclinical: no symptoms
Nosocomial: acquired in hospital/medical clinic setting
What is the membrane structure of gram pos and neg bacteria?
Neg: two membranes, thin peptidoglycan
Pos: one membrane, thick peptidoglycan
What is peptidoglycan?
Aka the cell wall
What is included in the cell envelope?
IM/CM, PG and OM
What is the cell membrane called from gram pos and neg bacteria?
Neg: inner membrane
Pos: cytoplasmic membrane
What is the architecture of the outer membrane?
Permeability barriers: beta barrel OMPs, LPS
What is the structure of the inner membrane?
Alpha helical proteins: maintain proton gradient, site of energy production and active transport
What is Peptidoglycan?
NAG-NAM sugars and proteins: maintains the cell shape, makes enzymes called PBPs
What are some exceptions to the gram neg/pos binary?
- Thick PG+2 membranes
- PG+2 membranes+NO LPS
True or false: bacterial cell surface molecules can be modified by the host to prevent an innate immune response against the microbiota
True
