Lecture 3-4: Host-Pathogen-Environment Interaction Flashcards
Define: HOST
any organism that supports the survival and growth of microorganisms
Define: SAPROPHYTE
organisms that live on dead or decaying organic matter; usually not parasite but can cause disease
Define: PARASITE
general term for an organism that lives on or within another living organism
Define: COMMENSAL
an organism that lives in or on a host but does not cause disease; organism benefits but host may or may not; most of the bacteria in the intestine, skin, and mm
Define: ENDOGENOUS infection
Infection coming from commensals
Define: EXOGENOUS infection
Infection coming from environmental bacteria
Define: PATHOGENs
Those bacteria that are capable of causing disease
Define: PATHOGENICITY
The capacity of bacteria to produce disease in a host (yes/no)
Define: VIRULENCE
Variation in the pathogenicity (degree of pathogenicity: lots of disease or little amount of disease)
List some pre-disposing factors for infection by opportunistic pathogens.
Damaged tissues AND Impaired innate defense mechanisms are MOST COMMON;
Introduction to body sites where not normally found;
Disturbance of the normal flora (antibiotics);
Define: INFECTIVITY
capacity of organism to become ESTABLISHED in the host tissues;
involves: ability to penetrate tissues, survive host’s defenses, and multiply/disseminate within the host
Which Adaptive Immunity targets extracellular defense?
AMI - Antibody Mediated Immunity
Which Adaptive Immunity targets intracellular defense?
CMI - Cell Mediated Immunity
What must you do in order to properly treat ALL bacterial infections?
Identify the UNDERLYING CAUSE
What must bacteria be capable of to cause disease?
Attach, Invade, Evade, Damage/Dysfunction
What are virulence factors of ADHESION?
Pili (especially Gram -) and Adhesion factors
What are virulence factors of INVASION?
Bacteria can entire either Actively OR Passively;
Passive: through damaged tissues
Active: via intact epithelium using TOXINS
What are some virulence factors for SURVIVAL INSIDE TISSUES?
Anti-phagocytic molecules: M-proteins, Capsule, slime layer, biofilm;
Iron sequestration: Siderophores - bacteria MUST have Iron to survive;
Survival in protected sites: some can survive extra long in hard to reach places (lepto in kidney)
Intracellular survival: Facultative and Obligate - common of Major pathogens (S. aureus, Salmonella, Brucella)
What is a virulence factor for survival in tissues and tissue DESTRUCTION?
Toxins - Evade, Damage and Dysfunction
Can directly damage, indirectly damage, cause specific dysfunction
Endotoxin vs. Exotoxin
What table should we absolutely KNOW for toxins?
Table of page 35 of notes
Is exotoxin produced by Gram (-) bacteria, Gram (+) bacteria, both or neither?
Both
Endotoxin or exotoxin: Is often spontaneously diffusible.
Exotoxin
Endotoxin or exotoxin: Is cell bound as part of the cell wall.
Endotoxin
Endotoxin or exotoxin: Is an LPS complex containing Lipid A, core polysaccharides, and O-side chains
Endotoxin
Endotoxin or exotoxin: Heat labile
Exotoxin
Endotoxin or exotoxin: VERY STABLE to heat, chemicals, and storage.
Endotoxin
Endotoxin or exotoxin: Potent toxins
Exotoxin
Endotoxin or exotoxin: Pyrogenic (fever inducing)
Endotoxin
Endotoxin or exotoxin: Highly antigenic
Exotoxin
Endotoxin or exotoxin: Often readily converted to toxoids which induce neutralizing antibodies
Exotoxin
Endotoxin or exotoxin: Encoded in the bacterial chromosome
Endotoxin
Endotoxin or exotoxin: Synthesis determined extrachromosomally (plasmid/phage)
Exotoxin
Endotoxin or exotoxin: Action is similar regardless of bacterial species of origin
Endotoxin
Endotoxin or exotoxin: Different toxins have different effects
Exotoxin
Endotoxin or exotoxin: Cause cell membrane damage and subsequent damage through: enzymatic digestion and formation of pores
Exotoxin
Endotoxin or exotoxin: Causes widespread release of pro-inflammatory cytokines and host derived mediators
Endotoxin
