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38 Cards in this Set

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  • Back
Virulence
The qualitative measure of pathogenicity

determined by invasiveness, toxicity and other factors
Opportunistic Pathogen
causes diseases in teh absence of normal host resistance
True or False: Most of microbes are nonpathogenic and do not cause harm
True
Infection
Any situation where a microbe is established and growing in a host

Host is not necessarily harmed in infection
Disease
Damage or injury to the host that impairs host function
Differing Environments for infection
Skin (Dry environment)

Lungs (Oxygenated Environment)

Large Intestine (anaerobic environment)
Mucous Membranes
Common site where infection begin
Mucus
viscous glycoprotein that covers mucous membranes

may be loosely or tightly associated with the mucosal surface
What determines if tissue infection occurs?
The type of microbe association with mucosal surface
True or False: Human skin is generally not a favorable place for microbial growth
True
Transient Microbes
unable to multiply on the skin and usually die

most are gram (-) as they cannot compete with gram (+) bacteria
Resident Microbes
survive and multiply on skin

most are gram (+)

gram (+) better suited for dry environments
What factors increase resident microflora?
1) Weather

2) Age

3) Hygiene
Lysozymes
found in saliva

can cleave glycosidic linkages in teh peptidoglycan of bacteria
Dental Plaque
bacteria growth on tooth surfaces in thick layers

begins as glycoprotein that grows into a thick layer

caused by species of streptococcus
Oral Microbes
produce large amounts of organic acids that cause decalcification of tooth enamel (cavities)

can also lead to gingivitis
Acidity in intestine
Very acidic in the duodenum portion and becomes more neutral in pH toward its distal end

distl end of samall intestine and entire large intestine are both neutral in pH therefore microbes more prevalent in these neutral environments
Microflora in Colon
Mostly obligate anaerobes, although some faculative aerobes

composition of microflora and diet have a large influence on what metabolic compounds are produced
Four microbes most commonly found in Upper respiratory tract
1) Staphylococci

2) Streptococci

3) Diphtheroid bacilli

4) gram (-) cocci
Microbes in Upper Respiratory Tract
potentially harmful bacteria are often part of the nasal flora of healthy individuals

do not cause disease if the other resident microbes out compete the potentially harmful types and limit pathogen growth
Microbes in lower respiratory tract
has no resident microglora

ciliated epithelial tissue push microbes and debris away from the trachea bronchi and lungs
What is responsible for bacterial adherence to host tissue cells
macromolecules like polysaccharides, proteins or glycoproteins

these are usually synthesized and secreted by the bacteria and extend outward forming slime layers or capsule structures
Four types of nutrients for pathogen
Vitamins, amino acids, sugars, organic acids
Erythritol
important growth factor

helps brucella abortus gorw in cattle
Iron
greatly influences microbial growth

Transferrin and lactoferrin proteins in animals bind iron tightly
Siderophores
proteins that remove iron bound to transferrin
Toxicity
ability of an organism to cause disease by means of a toxin that inhibits host cell function or kills host cells
Invasiveness
ability of an organism to grow in a host tissue in such large numbers that the pathogen inhibits host function
Attenuation
the loss of virulence by a microbe or a strain
Three toxins produced by Salmonella
1) Enterotoxin

2) Endotoxin

3) Cytotoxin
Enterotoxin
extracellular toxin that damages the host small intestine
Endotoxin
LPS layer toxin that beocmes toxic when solubilized
Cytotoxin
toxin that inhibits host cell protein synthesis by inducing a leak of calcium ions forom the host cell
How does salmonella establish infection?
Through intracellular parasitism

grow inside clelse that line the intestins as well as in phagocytic cells of the host immune system
Virulence Factors
extracellular proteins produced by pathogens that aid in teh establishment and maintenance of a disease
Hyaluronidase
breaks down hyaluronic acid in host cells

"intercellular cement"
Streptokinase
dissolves clots

produced by streptococcus pyogenes
coagulase
promotes clot formations

produced by s. aureus