MICROBIAL MECHANISMS OF PATHOGENICITY Flashcards by michaela gail

the ability of an organism to cause disease

pathogenicity

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the severity or harmfulness of a disease

virulence

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portals of entry

mucous membranes, skin, parenteral routes

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microorganisms can gain access in the GIT in food and water via ___

contaminated fingers

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portal of entry for pathogens that are contracted sexually

gut

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preferred portal of entry of salmonella typhi

mouth - swallowed

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preferred portal of entry of stretococcus pneumoniae

nose / mouth - inhaled

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preferred portal of entry of yersinia pestis

more than one portal of entry - can cause plagues

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number of invading microbes - virulence

ID 50

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number of invading microbes - toxin potency

LD 50

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number of microbes to cause cutaneous anthrax

10-50 endospores

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number of microbes to cause inhalation anthrax

10,000 - 20,000 endospores

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number of microbes to cause gastrointestinal antrax

250,000 - 1M endospores

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lethal dose of botulinum toxin in mice

0.03 ng/kg

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lethal does of shiga toxin

25 ng/kg

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ability of microorganisms, such as bacteria or viruses, to attach to host cells or surfaces

adherence

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attaches to teeth by means of its glycocalyx which is primarily made up of dextran

streptococcus mutans

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have fimbriae that adhere to the glycocalynx of s. mutans

actinomyces

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have adhesions on fimbriae that adhere only to specific kinds of cells in the small intestine

shigella and e. coli

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uses tapered end as a hook to attach to host cells

treponema pallidum

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produces an edhesion for a specific receptor on a host cell

listeria monocytogenes

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has a fimbriae with adhesions

neisseria gonorrhoae

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has a mechanism of adherence that resembles viral attachment

staphylococcus aureus

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protective layers surrounding some bacteria that enhance their ability to evade the host’s immune system
help bacteria avoid phagocytosis by immune cells and may facilitate adhesion to host tissues

capsules

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enzyme that coagulates blood

coagulase

enzyme that digest fibrin clots

kinases / fibrinolysin

enyme that hydrolyzes hyaluronic acid

hyaluronidase

enzymes that hydrolyzes collagen

collagenase

enzyme that destroys IgA antibodies

IgA proteases

enzyme that breaks down RBC

hemolysis

enzymes that breaks down phospholipids, and destroy the plasma membrane of RBC

lecithinase

enzyme that destroys neutrophils

leukocidins

process of altering surface antigens thus evading immune response

antigenic variation

surface proteins that rearrange nearby actin filaments of the cytoskeleton

invasins

- a glycoprotein that bridges the junctions between cells - used by certain microbes to move from cell to cell

cadherin

proteins that exhibit a high affinity to iron

siderophores

poisonous substances that are produced by certain microorganisms

toxins

capacity of microorganisms to produce toxins

toxigenicity

refers to the presence of toxin in the blood

toxemia

what are the 2 types of toxins?

exotoxins, endotoxins

- produces mostly by gram positive bacterium - chiefly made up of protein - part of growth and metabolism

exotoxins

- release following lysis of bacterial cell - carried by bacterial plasmids - soluble in fluids

exotoxins

- most lethal substances known - disease specific

exotoxins

anitbodies produced by the body that provide immunity to exotoxins

antitoxins

inactivated toxin used in a vaccine

toxoids

true or false - diptheria and tetanus cannot be prevented by toxoid vaccination

false

what are the 3 principal types of exotoxin?

a-b toxins, membrane-disrupting toxins, superantigens

- also called type III toxins - 2 polypeptide parts - first toxins to be studied

A-B toxins

the A part of the A-B toxin is the ___ components while the B part is ___

active (enzyme), binding

- also called type II toxins - damage of destroy the integrity of cell membranes

membrane-disrupting toxins

disrupting toxins that kill phagocytic leukocytes

leukocidins

membrane-disrupting toxins that destroy erythrocytes

hemolysin

- also called type I toxins - stimulate the proliferation of immune cells called T cells with release of enormous amounts of cytokines

superantigens

toxins that cause food poisoning and toxic shock syndrome

superantigens

- made up of lipopolysaccharides - released when bacteria dies, and cell walls lyse

endotoxins

- stimulates macrophage to release cytokines in very high concentrations - produce the same signs and symptoms (chills, fever, weakness, generalized aches, shock, sometimes death)

endotoxins

- can induce miscarriage - severe consequences include DIC (blood coagulation disease) and shock

endotoxins

- small, circular, DNA molecules capable of independent replication - resistance (R) factors

plasmids

incorporation of viral DNA into the bacterial chromosome

lysogeny

the newly integrated genetic material because of lysogeny is now called a ___

prophage

a bacterial cell contaning a prophage

lysogenic

exhibition of new properties codes by the prophage in the bacterial cell, both the host cells and its progeny

lysogenic conversion

- evading host’s defense - damage or death of the host cell while reproducing themselves

viruses

structural and functional changes in host cells caused by a viral infection

cytopathic effects

ability of a virus or other pathogen to kill host cells

cytocidal effects

impact of a virus or other pathogen on host cells that does not result in cell death

noncytocidal effects

doesnt have a well-defined set of virulence factors

fungi

- inhibit CHON synthesis - causes headaches, chill, severe nausea, vomiting and visual distrubances

trichothecenes

tricothecenes toxin is produced by

fusarium (from grains and rice)

- an alkaloid - produced by claviceps pupurea - found in scleoria - causes hallucination and limb gangrene

toxin ergot

- produced by aspergillus flavus - found in nuts which is carcinogenic

aflatoxin

- produced by amanita phalloides - may result in death

mycotoxins

inavde host cells and reproduce within them, causing their rupture

plamsodium

attaches to macrophages and gains entry by phagocytosis

toxoplasma

attach to host cells and digest the cells and tissue fluids

giarda lablia

produces neurotoxins

algae

- produced by some genera of dinoflagellates such as Alexandrium - causes Paralytic Shellfish Poisoning

saxitoxin

- use host tissues for growth and metabolism - waste products can lead to disease symptoms

helminths