Micro Lecture 3 Flashcards
Commensalism
One org. benefits, other is unaffected + / 0
Mutualism
Both orgs. benefit + / +
Parasitism
One org. benefits at expense of another + / -
Microbial antagonism
Competition between microbes
Bacteriocins
Proteins that inhibit growth of other bacteria
Opportunistic pathogens
Cause disease in compromised host
Koch’s postulates
Prove the cause of infectious disease (same pathogen, isolated, cause disease in healthy animal, isolated from inoculated animal)
Name two microbes that have never been cultured.
Syphilis, leprosy
Signs
Changes (symptoms) that can be measured/observed
Incidence
Number of people who develop disease during particular time period
Prevalence
Number of people who have disease at a specified time
Focal infection
Systemic infection that began as local infection
Reservoirs of infection
Human, animal, nonliving (water, soil)
Secondary infection
Opportunistic infection after primary infection
Subclinical disease
No noticeable signs or symptoms
Indirect contact transmission
Spreads to host by nonliving object (fomite), ex. syringes
Droplet transmission
Airborne droplets less than 1 meter
Vectors
Arthropods, via mechanical (carries on feet) or biological (bites, feces)
Vehicle transmission
Waterborne, foodborne, airborne
Nosocomial infections
Hospital associated infections, microorganisms, weakened status of host, chain of transmission
Control measures to reduce pathogens
Handwashing, disinfection, cleaning instruments, disposable bandages
Infectious dose for 50% of sample pop.
ID 50
Lethal dose for 50% of sample pop.
LD 50 (potency of toxin)
How do pathogens attach to host tissues?
Adherence via adhesins (ligands bind to receptors on host)
*Microbes form biofilms
List cell wall components
M protein: resists phagocytosis
Opa protein: allows attachment to host
Waxy lipid: resists digestion
Coagulase
Coagulates fibrinogen
Kinase
Digests fibrin clots
Hyaluronidase
Digests polysaccharides that hold cells together
Collagenase
Breaks down collagen
IgA proteases
Destroys IgA antibodies
Antigenic variation
Pathogens alter surface antigens (antibodies rendered ineffective)
Invasins
Surface proteins produced by bact. that rearrange actine filaments (membrane ruffling)
Siderophores
Proteins secreted by pathogens, bind iron (Fe) more tightly than host cells, ex. enterobactin
Exotoxins
gram +, A-B toxins, membrane disrupting, genotoxins
Antitoxins
Antibodies against specific exotoxins
Toxoids
Inactivated exotoxins used in vaccines
A-B toxins
Contain enzyme and binding components, ex. diptheria toxin
Leukocidins
Kill phagocytic leukocytes
Hemolysins
Kill erythrocytes via protein channels
Streptolysins
Hemolysins produced by streptococci
Superantigens
Intense immune response due to release of cytokines from host cell
Genotoxins
Damage DNA
Lipid A
Endotoxin, part of LPS of gram neg. bact., released during bact. multiplication/when gram neg. bact. die
Lysogenic conversion
Changes characteristics of microbe due to incorporation of bacteriophage
Infective agent of Chlamydiae
Elementary body
How is Rickettsia transmitted?
Insect/tick bites