Ch.15 Microbiology Flashcards
Pathogenicity
ability to cause disease by over coming host defenses
Virulence
extent of pathogenicity (how serious it is)
Portal of entry
Mucous membranes, Skin, parenteral route (cuts bites wounds). Preferred portal of entry is what a microbe prefers
IDv50
Infectious dose for 50% of the test population, shows virulence
LDv50
lethal dose, of a toxin
Parenteral route
portal of entry but only through injury or penetration
how is adherence and adhesion achieved
adhesins/ligands bind to surface receptors of their host cells.
Where are a pathogens ligands/adhesins located?
some on the glycocalyx, fimbriae, flagella. , opa and M protein (has 100 types)
Biofilms
masses of microbes that share resources and come together. They are resistant to disinfectants and antibiotics
How do capsules protect pathogens
they prevent phagocytosis, by stopping the phagocytes from adhering
What cell wall components protect pathogens
M proteins- resist phagocytosis
Opa protein- inhibits T helper cells
Mycolic acid (waxy lipid)- resists digestion
Coagulase
bacterial enzyme’s that coagulate fibrinogen (blood clots)
Kinases
digest fibrin clots that the body makes to isolate bacterial infection
Hyaluronidase
hydrolyzes hyaluronic acid, a polysaccharide that holds together certain cells of the body
Collagenase
hydrolyzes collagen which is found in connective tissue like muscle and organs
Iga proteases
kill antibodies
Antigenic Variation
the changing of pathogen antigens, so that antibodies do not kill them
Siderophores
proteins take away nutrients from its hosts, like iron away from hemoglobin.
Invasins
proteins secreted by pathogens in order to manipulate the cytoskeleton of host cells via its actin. They use actin and cadherin to propel themselves from cells to cell
How do pathogens damage cells
Disrupt cell functions, produce waste products and toxins
Toxin
substance that contributes to pathogenicity
Toxigenicity
ability to produce a toxin
toxemia
presence of toxin in host blood
Toxoid
inactivated toxin used for a vaccine
Antitoxin
Antibodies against a specific toxin
Exotoxins
produced inside pathogenic bacteria, and secreted outside the cell . Manly gram positive
Endotoxins
Mainly gram negative, are kipid portions of the outer membrane, secreted when the bacteria die and fall apart.
Exotoxins categories
A-B toxins, Membrane disrupting toxins, Super antigens
How do a-b exo toxins toxins work
AB is made by bacteria , the B (binding portion) goes into the host cell receptor and then the plasma receptor , enters receptor mediated endocytosis. they enter and the A part disrupts the cell while the B cell leaves and the cell receptor back to be reused.
What do membrane - disrupting toxins do
make protein channels in the plasma membrane , some disrupt the phospholipid bilayer
What do super antigen exotoxins do
cause an intense immune response due to release of cytokines from host cells those stimulate T cells. Examples are food poisoning and toxic shock syndrome
Exotoxin overview
mostly gram positive, by products of growing cell. Protein, generally no fever, neutralized by antitoxin and LD50 is small
Endotoxins overview
mostly gram negative, in the outer membrane, Lipid, causes fever , not neutralized by antitoxin the LD50 is relatively large
How do endotoxins cause fever
a macrophage ingests a gram negative bacteria, the endotoxins are released that cause the macrophage to produce cytokines. the cytokines go to the hypothalamus that produce prostaglandins.
LAL Assay
Used to detect endotoxin. use amoebocytes from a literal horshoe crab . They have protein that cause clotting if there are endotoxins present . lysis occurs
Cytopathic effects of viruses part 1
stops macromolecular synthesis in host cells, host cell lysosomes release enzymes and kill themselves, form syncytium that are multineclie cells made of multiple infected cells
Cytopathic effects of viruses part 2
Cytocidal (cell death) , inclusion bodies, parts of viruses in the middle of becoming virusus, transformation, and destruction of T cells.
Pathogenic effects of fungi
fungal waste products can cause symptoms, allergic response , toxins can inhibit protein synthesis, proteases modify cell membranes, capsules can prevent phagocytosis
Pathogenic effects of fungi
ergot toxin (LSD), constrict blood flow, Aflatoxin, carcinogenic substance, Mycotoxins neurotoxins.
Pathogenic effects of protozoa
presence can cause diarrhea, protozoan waste products can cause symtpoms, grow in phagocytes, antigenic variation
Pathogenic effects of protozoa
use host tissue and interfere with functions. the waste can cause symptoms
Pathogenic properties of Algae
neurotoxins from diatoms, and dinoflagellates, Demonic acid and asxitoxin
Portal of exit
respiratory tract , caogh and sneese gastroinsteinal tract poop and saliva , genitourinary tract urine, and vaginal secretions. , skin, blood
