Med Bac T_Quiz 2

Intracellular residence
- invasins
- protection from innate immune system
- not 100% fool proof (cytotoxic T cells)
- ex. Mycobacterium tuberculosis in macrophage
- have ability to prevent lysosome and phagosome from fusing or stop pH from dropping

Bacterial capsule (polysaccharide layer)
- prevents membrane attack complex (MAC) in complement cascade
- prevent antimicrobials from accessing cell
- prevent antigens from being detected
- tested by Griffith's classic experiment (smooth vs. rough strains) with transformation (when organism takes up DNA from surrounding environment and express it)

Modifying surface structures
- LPS (lipopolysaccharide) on surface of Gram - bacteria
- can modify phosphate groups in inner core into other groups that isn't so negatively charged to repel positively charged antimicrobials
- change composition of antigens in O antigen

- responsible for millions of deaths every year
- two subunits (A and B)
- B recognizes host cell and binds to receptor on host cell to gain entry into cell
- A does the damage/toxic activity
- ADP-Ribosylation (toxin adds ADP-ribose to part of genome)
- gene carried by virus (can cause bacteria w/out toxin gene to get it)

Examples:
- Diphtheria toxin produced by Corynebacterium diphtheriae (toxin adds ADP-ribose onto TEF (translation elongation factor) which leads to shut down of translation in cell = no more protein = cell death)
- Cholera toxin produced by Vibrio cholerae (kills by dehydration by diarrhea) (toxin adds ADP-ribose to G protein = causes non-homeostasis draws water out into intestine w/ ions via chloride channels = diarrhea = death)
- Tetanus toxin produced by Clostridium tetani (toxin targets neurons, spastic paralysis) (one of the most toxic)
- Botulinum toxin produced by Clostridium botulinum (flaccid paralysis) (one of the most toxic)

- hemolysin disrupts cell membrane of RBC (causes RBCs to lyse open) (inserts barrel end into cell membrane to create pore)
- bacteria uses the iron in hemoglobin
- can streak bacteria on blood agar and see hemolysis (alpha, beta, gamma) to identify organisms

- LPS (lipopolysaccharide)
- Gram neg. bacteria
- on outer membrane
- Lipid A in membrane (anchor) (similar b/w species) (conserved)
- core (linker region) (some diversity b/w strains) (fairly conserved)
- O antigen (long chain that varies) (different carbohydrates that link in different ways) (very diverse)

- induce inflammation and fever as an immune response
- Reaction to endotoxins can lead to anaphylactic shock and death
- sepsis

intoxication illness = when you consume toxic material but not live organisms themselves (ex. foodborne intoxication: bacteria killed by cooking/heat but toxins not inactivated)

infection = consuming organisms that cause the illness

Active
- deliver actual etiologic agent (or part of it) to host and they build their own immune response to it (prevention)
- Pro = activate memory cells/long lasting immunity
- Con = takes several weeks to become immune

Passive
- deliver antibodies to host
- Pro: immediate immune response
- Con: immune system (yours) doesn't have memory for future infections (no lasting immunity)
- ex. breastfeeding, convalescent plasma (CCP)

Inactivated
- killed organism
- can't cause infection
- Pro: no risk of infection
- Con: not as strong immune response

Attenuated
- modified live organism
- can cause mild disease/infection
- miss the things that make them bad (lose abilities to replicate in human cells)
- better immunity and long lasting
- ex. Tuberculosis; BCG = cow version