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z-MicroBio Final - Ch. 21
Dr. White UCF
51
Microbiology
04/30/2009

Additional Microbiology Flashcards

 


 

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Term
Mutualism
Definition
both host and microbe benefit
Term
Commensalism
Definition
microbe causes no damage to host
Term
Pathogenic relationship
Definition
microbe causes damage to host
Term
Normal Flora
Definition
microorganisms normally found in or on the body that typically do not cause disease
Term
Synergistically
Definition
capable of working together; two microorganisms are synergistic if they are able to produce a host response greater than the sum of the effects they produce when acting alone
Term
Communicable
Definition
able to be transmitted between hosts
Term
Disease reservoir
Definition
a natural source of disease agent. Reservoirs may include sick patients, asymptomatic carriers, animals, recovered patients, environmental sources, etc
Term
virulence
Definition
The measure of degree pathogenicity
Term
opportunistic pathogen
Definition
if host defense mechanisms are weakened, it becomes an opportunistic pathogen.
Examples:
AIDS patient: Pneum. carnei
Woman whose normal flora are killed by antibiotics frequently gets this Candida yeast infection.
Aspergillis niger eye infection in immunocompromisedhost.
Term
Compromised Host
Definition
Compromised Host has lowered resistance to infection and ultimately disease.
Malnutrition, Alcoholism
Trauma from surgury or an injury
Cancer or leukemia
Diabetes
Immunosupression due to drugs, viruses like HIV, genetic deficiencies
Altered normal flora due to antibiotics
Term
Infection
Definition
refers to any situation in which a microorganism is established and growing in or on a host, regardless of whether or not the host is harmed !!
Term
Infestation
Definition
Presence of organism; not growing and reproducing; just presence
Term
Disease
Definition
damage or injury to the host that impairs host function. Infection is not synonymous with disease!!!!! Normal flora can sometimes cause disease if the host resistance is compromised!!!!
Term
Internal tissues Free from Bacteria
Definition
brain, blood, cerebrospinal fluid, muscles. Genitourinary Tract-upper [kidney, ureters, & uninary bladder. Stomach (Mycobacteria, Salmonella are resistant.)
Term
Entry of Pathogen
Definition
[image]
Term
Adherence
Definition
Bacteria or viruses usually initiate infection by adhering specifically to epithelial cells through interactions between macromolecules on surfaces of the pathogen and host.
Term
Tissue Selective
Definition
Neisseria gonorrhoeae adheres more strongly to urogenital epithelium (tissue specificity). Opa surface protein binds with host CD66 protein.
Term
Host Selectivity
Definition
a microorganism that normally infects humans binds to human epithelial cells better than those of a rat
Term
Capsules
Definition
glycocalyx or slime layer (loose network of polymer fibers) may be involved in adherence.
Term
Fimbriae & Pili
Definition
are bacterial surface proteins structures that also function in attachment (bind host cell glycoproteins).Enterotoxic strains of E. coli express fimbrial proteins called CFA (Colonization factor antigens) that adhere specifically to cells in small intestine. Produce enterotoxins.
Term
Virulence
Definition
Invasiveness: grow in large numbers and may spread throughout host body
Toxigenicity: toxins that inhibit host cell function or kill host cells. Two types: Exotoxins & Endotoxins
Term
Resistance
Definition
Acquired or Induced Immunity(Resistance)
Humoral Immunity: mediated by antibodies
Cellular Immunity: mediated by cells (T cells)
Natural Resistance or Innate Immunity
Cells: macrophages
Mechanical Barriers: skin & mucous membranes
Chemical Factors: interferon, fatty acids on skin
Microbial Factors: Normal flora competition
Term
Virulence Factors: Invasiveness
Definition
Hyaluronidase
Coagulase
Fibrinolysin
Lipase
Collagenase
Leukocidins
Streptokinase and Streptodornase
Term
Hyaluronidase
Definition
This is also called the spreading factor because it catalyzes the breakdown of hyaluronic acid, the substance that cements the human cells together. This allows the bacterial cells to spread through tissue causing a condition known as cellulitis.[Staphyloccus, Streptococcus & Clostridia]
Term
Coagulase
Definition
This enzyme catalyzes the conversion of fibrinogen to fibrin with resultant clot formation. Present in pathogenic Staphyloccus.
Term
Fibrinolysin
Definition
This catalyzes the conversion of plasminogen to the fibrinolytic enzyme plasmin. Thus it acts opposite of coagulase. In Staphylococcus aureus, the gene for fibrinolysin is on a bacteriophage and is expressed during lysogeny.
Term
Lipase
Definition
Production of excessive amounts of lipase allow bacteria to penetrate fatty tissue with the consequent formation of abscesses.
Term
Collagenase
Definition
This enzyme catalyzes the degradation of collagen, a protein found in tendons, nails and hair.

Term
Leukocidins
Definition
cause lysis of white blood cells; Staphyloccus aureus
destroys rbc’s & other tissue cells
Term
Streptokinase and Streptodornase
Definition
actually fibrinolytic enzymes (category 3)
lyse rbc’s
Term
Capsules
Definition
antiphagocytic
Term
Pilli
Definition
attachment to surface receptors on host cells
Term
LD50
Definition
(lethal dose50)
The LD50 is the dose of an agent that kills 50%of the animals in a test group
Term
Invasiveness
Definition
the ability of an organism to grow in host tissue
Term
Toxicity
Definition
the ability of an organism to cause disease by means of a preformed toxin that inhibits host cell function or kills host.

Term
Colonization and Growth
Definition
When a pathogen gains access to tissues, it may multiply; a pathogen must grow within host tissues to produce disease. After adherence to epithelial, microbe may penetrate through small breaks or lesions or even an intact mucosal surface, esp if normal flora is altered.
Disease results when anatomical and/or physiological damage occurs
Term
Virulence Factors
Definition
[image]
Term
Endotoxins vs Exotoxins
Definition
[image]
Term
Toxoid
Definition
Toxin -> Heat or chemical treatment -> Toxoid -> inject into animal -> Antitoxin
Term
EXOTOXINS: GENERAL TYPES
Definition
Cytolytic toxins
A-B toxins
Superantigen toxins
Term
Cytolytic toxins (hemolysins)
Definition
damage cell membranes, causing cell lysis & death
Term
A-B toxins
Definition
B promotes specific binding of toxin to host cell receptor. A is the toxic part
Term
Superantigen toxins
Definition
Stimulate large numbers of immune lymphocytes and causes systemic as well as inflammatory responses
Term
EXOTOXINS: SITE OF ACTION
Definition
Cytotoxins: inhibit a cell function or cause cell death
Neurotoxins: inhibit nerve transmission
Examples: tetanus and botulinum toxin
Enterotoxins: alter permeability of intestinal epithelium
Examples: Cholera and Staph aureus food poisoning enterotoxin (also superantigen)
Term
Diptheria Cytoxin[A-B toxin]
Definition
Diptheria toxin in an A-B toxin that inhibits a cell function: protein synthesis
B promotes binding of toxin to cell membrane
When it binds to cell membrane, it is cleaved and A is internalized.
A catalyzes ADP-ribosylation of EF-2 and it no longer aids the transfer of amino acids to growing polypeptide chain.
Only a single toxin molecule is needed to kill a cell.
Diptheria toxin is formed only by strains of Corynebacterium diptheriae cells that are lysogenized by phage beta.
Term
Lysogenic versus Lytic
Definition
[image]
Term
Exotoxins - Neurotoxins Botulinum
Definition
Botulinum toxin:
7 distinct toxins-2 of which are encoded for by genes on lysogenic bacteriophages
Toxin binds to presynaptic terminal membranes at nerve-muscle junction, blocking the release of acetylcholine required for transmission of nerve impulse to muscle.
Muscle contraction inhibited & have flaccid paralysis
1 mg kills 1 million guinea pigs
Term
Exotoxins - Neurotoxins Tetanus
Definition
Tetanus toxin:
2 polypeptides, fixed to nerve synapsis, blocks release of glycine, a factor that induces muscle relaxation
Relaxation signal is blocked & paired muscles both contract
Spastic paralysis, twitching paralysis
Term
Exotoxins - Enterotoxins
Definition
Enterotoxins alters permeability of intestinal epithelium; causes massive secretion of fluid into the intestinal lumen causing diarrhea
Staphylococcus aureus - vomiting, diarrhea
Vibrio cholera -
Cholera toxin: 3 polypeptides (A1, A2, B)
B toxin involved in binding to ganglioside GM1 in epithelial cytoplasmic membrane
A1 activates adenylate cyclase to produce cAMP which brings about secretion of chloride and bicarbonate ions from mucosal cells in intestinal lumen which causes water secretion into lumen
Term
Endotoxins
Definition
Gram-negative bacteria produce lipopolysaccharides as part of the outer layer of their cell envelope
These are called endotoxins because they are generally cell-bound but are released in large amounts when the cells are lysed
Stimulates host cells to release proteins called endogenous pyrogens causing fever
Other symptoms: diarrhea, rapid decrease in lymphocyte, leukocyte, and platelet numbers, generalized inflammation, death
Not as toxic as exotoxins. Ex: LD50 for mice is 200-400 g for endotoxin but LD50 for botulinum toxin is about 25 picograms (pg), about 10 million times less.
250o C for 30 minutes for inactivation
Major problem if contamination of medical devices
LPS affects macrophages, monocytes, and neutrophils by binding to a receptor on these cells & tranfer to a CD 14. LPS-CD14 then complexes with a Toll-like receptor to initiate a response that releases cytokines & tumor necrosis factor alpha.

Term
Portals of Entry
Definition
Food and Water Bourne:Staphylococci, Vibrio cholera, Clostridium botulinum
Exhalation Droplets: coughing & sneezing
Direct Contact: mononucleosis, syphillis, herpes, HIV[Retrovirus]
Animal Bite or Scratches:rabies, cat scratch fever
Vectors: Rocky Mt. spotted fever, bubonic plague