Damage

Degree of damage varies from _____ and varies among _____

pathogen; patients

What are the three causes of symptoms/damage?

immunopathology, inflammation, and direct action of pathogen

How does indirect tissue damage occur?

innate response or antibody response when they are sent to inflammed sites

______ is a leading cause of death for children

diarrhea

How does diarrhea cause death?

by depleting body fluids resulting in profound dehydration

What are most diarrhea associated death attributatble towards?

unsafe water, inadequate sanitation, and insufficient hygiene

How are most cases of diarrhea spread?

via fecal-oral route through contaminated water, food, or objects

What is the difference between food poisoning and intestinal infections?

rapid onset, very little replication is needed for infection to occur vs infection developed in host

What is the microbial cause for diarrhea?

mechanism for shedding; microbial toxins, microbial invasion, and damage to epithelia are ways to promote transmission

What is the host-induced cause of diarrhea?

to rid the body of infectious agent; if taking anti-diarrhea meds, stops this mechanism and keeps the bacteria in (antibiotic more effective than anti-diarrhea meds)

Why do skin rashes form?

often a result of immune activity; common in certain bacterial and viral infections; useful for diagnosis

___% of cancers are caused by viruses

15

What does rhinovirus do to respiratory epithelium?

damages it; kills cilia in mucociliary escalator

Describe the process of bacterial-induced cell death

extracellular bacteria attach to host cells; bacteria enters the host cell; bacteria hide in vesicles and replication; replication can stop, allowing bacteria to hide from immune system; replication resumes until host nutrients are exhausted; bacteria damage and leave the host cell; bacteria spread to new cells

Describe mechanical damage from worms?

can cause physical obstructions blocking flow through organs

Why do worms like the common bile duct?

worms are more protected from peristalsis but blocks duct

What are exotoxins?

proteins that are produces by gram positive or gram negative bacteria that alter a function or kill the host cell; causes direct damage; cytolytic enzymes, receptor-binding proteins, superantigens

What is an endotoxin?

induces immunopathology, part of bacterial cell wall, normally only released when the bacterial cell dies; stimulates immune response but doesn’t cause direct damage

Toxins are often the targets of _____

vaccines

Toxins act on….

intracellular targets, cell surface, extracellular matrix

How do exotoxins modulate intracellular targets?

usually secreted by bacteria, bind to cellular receptors, become internalized

How do Type III cytotoxins modulate intracellular targets?

infected directly into host cell via type III secretion system; contact-dependent

How do Type IV to VII cytotoxins modulate intracellular targets?

injected directly into host cell via type IV, V, VI, or VII secretion system; contact-dependent

How do endotoxins (LPS) act at the host cell surface?

acts through TLR4, causes secretion of cytokines, causes immunopathology at high concentrations

How do membrane-damaging toxins (hemolysins) act at the host cell surface?

lipases, pore-forming

How do superantigens act at the host cell surface?

causes immunopathology; indiscriminate, non-specific activation of T cells or B cells

How do hyaluronidase, collagenases, elastase act on the extracellular matrix?

breaks down components of connective tissue

How do DNases act on the extracellular matrix?

thins out puss that is viscous from DNA released from dead leukocytes

How do streptokinase act on the extracellular matrix?

eliminates fibrin barriers (clot breakers)

What are the four toxin mechanisms/actions?

enzymatic lysis, pore formation, inhibition of protein synthesis, hyperactivation

How does botulinum affect muscles?

toxin blocks release of acetylcholine from vesicles which blocks stimulation, causing paralysis

What is the tetanus toxin?

causes painful muscle contractions, “lockjaw”, can interfere with breathing and be life-threatening, easily prevented with vaccine, treated with antitoxin and antibiotics

What is botulinum toxin?

caused by Clostridium botulinum; results in flaccid paralysis or muscle weakness; inhibits excitatory neurons at neuromuscular junctions; treated with antitoxin; can cause difficulty breathing

What is the cholera toxin?

produced by Vibrio cholerae; interferes with cAMP and affects ion channels; efflux of ions from cell causes water loss; causes acute diarrhea

What is the Diphtheria toxin?

produced by Corynebacterium diphtheriae; inhibits protein synthesis resulting in cell death

What is immunopathology?

damage caused by the host immune response to infection, host responses are necessary but sometimes damage the host in the process, contributes to many of the immediate signs and symptoms of an infection, helps the host survive

What is the composition of LPS?

conserved lipid A inserted into the cell membrane, responsible for hydrophobicity of the molecule; conserved core polysaccharide; repeating O polysaccharide responsible for the serological diversity to protect from hydrophobic compounds such as bile salts and antibiotics

What are the symptoms of inflammation?

redness, swelling, pain, heat

What are the symptoms of the influx of neutrophils?

puss, damage of extracellular matrix, staphylococcal abscess (fibrin capsule so hard to drain)

What is Staphylococcal toxic shock syndrome?

produced by Staphylococcus aureus and mediated by TSST-1 (superantigen); causes fever, hypotension, and a diffuse macular erythematous rash; high mortality without prompt antibiotic treatment; death caused by hypovolemic shock leading to multiorgan failure

Wat is streptococcal toxic shock syndrome?

toxins SpeA and SpeC superantigens cause this; pain, fever, chills, malaise, nausea, vomiting, and diarrhea; multiorgan failure

What is necrotizing fasciitis?

flesh eating disease caused by Streptococcus pyogenes; soft-tissue inflammation caused by immunopathology from superantigens and direct damage from exotoxins

What are the consequences of overactive adaptive immune responses?

prolonged infections or repeated antigenic stimulation can result in hypersensitivity; different types of depending on the immunological mechanism underlying the tissue-damaging reaction

What is hypersensitivity?

overreaction of the immune system