Flashcards in L12_Mechanisms of Bacterial Pathogenesis Deck (34)
An infection in which the host defenses clear the pathogen before any symptoms of disease are noted is called what?
Asymptomatic, inapparent, subclinical infection
A type of infection that can be passed from host to host
A highly communicable diease
An infection that comes from the environment, not a previous host (botulism, Legionnaires)
An infection in which the disease subsides, but microorganisms remain in the body and can restart disease later on is called what?
Host survives disease but continues to shed the pathogen indefinitely
Chronic carrie state
Describe the likelihood to cause disease, virulence, LD50, and ID 50 of a nonpathogen
Very unlikely to cause disease, very low virulence, very high LD50, very high ID50
Describe the likelihood to cause disease, virulence, LD50, and ID 50 of an Opportunistic Pathogen
unlikely to cause disease unless host is debilitated, low virulence, High LD50, Low ID50
Describe the likelihood to cause disease, virulence, LD50, and ID 50 of a pathogen
routinely causes disease in previously healthy host, mid to high virulence, low-mid LD50, range of ID50
What is a Virulence factor?
A gene found experimentally necessary for pathogens to produce disease.
Name some of the various functions of virulence factors (Top 5 categories)
survive extreme environments, adhesion, immune evasion, host cell takeover, poisoning the host.
One major category of virulence factors is exotoxins, secreted from the pathogen or injected into the host cell by T3SS, profound toxicity of these particles may result from the following effects
superantigenicity, interference with signal transduction, depolymerization of actin, or other activities.
What are toxoids and how are they made?
Heat or chemically inactivated exotoxins used for vaccines
Where are exotoxins generally coded?
Accessory DNA that comes into cell on plasmids or by phage injection, several factors may be regulated together on pathogenicity islands.
What are endotoxins and how do they work? Is vaccination protective agains them?
They are intrinsic toxins on the surface of bacterial. They cause immunogenic symtoms, neither previous exposure nor vaccination is protective.
What is a siderophore?
A molecule that binds and transports iron in microorganisms
Name three routes of vertical transmission of pathogens from a previous human host
Transplacental, Vaginal Delivery, Breast Milk
What is it called when a pathogen is transmitted from an animal to a human?
What is a fomite?
any object or substance capable of carrying infectious organisms, such as germs or parasites, and hence transferring them from one individual to another. (washcloth, countertop, etc.)
What is a vector?
vectors are organisms that transmit infections from one host to another
Give two examples of how pathogens can attach to host surfaces
Pili/fimbrae and biofilms
Describe the pyogenic and Ganulomatous immune responses and the main cell type involved in each.
Pyogenic- pus-forming, predominantly neutrophils
Granulomatous: macrophage kills most of bacteria, but some survive inside macrophages within a ganuloma.
endotoxins induce an immunogenic response which usually results in the overproduction o what two chemicals
TNF and IL-1
Name two species well know for producing superantigens
Strep pyogenes and Staph Aureus
Describe the 4 typical stages of infection.
Incubation, prodrome (nonspecific immunogenic symptoms like fever and fatigue), Specific Illness (Pathogen mediated symptoms), Recovery/convalescence
List four examples of virulence factors that help to survive extreme environments.
pH tolerance, Siderophores, Resistance to drying, resistance to detergents
Lis three examples of virulence factors that help in Host Cell takeover
Endosome escape pathway, actin polymerization, type 3 and 4 secretion systems
List three virulence factors that help with Adhesion
pili/fibrae, slime layer, adhesins
List five virulence factors that assist with immune evasion
Capsule (resists phagocytosis), IgA protease, Macrophage apoptosis factors, Antigenic Variation (trioanosomes), Serum resistance (ability to withstand complement)