Path Test 4: Infectious Diseases

Enters from outside the body

Already present as part of normal flora

Two dissimilar organisms living in close association

Living on or within, deriving benefit w/o injuring or providing benefit to another organism

Both organisms gain benefit, often cannot survive separately

One derives benefit while the other is harmed in some way

Parasite that lives outside the body

Parasite that lives within the body

Parasite whose entire life cycle occurs in one host

Parasite that requires more than one host

One organism derives no benefit while the other is harmed

Both organisms are harmed

Lack of interaction

Main host or one in which sexual cycle takes place

Temporary host for larval stages, asexual repro, development

Intermediate host actively involved in transmission

Transport host; other than intermediates host that carries parasites to definitive host

Alternate definitive host; maintains infxn

Alternative definitive host that for some reason is rarely infected, often the life cycle cannot be completed

GI tract bug:  causes malabsorption by numbers/ blocks epithelial surface

GI tract bug:  Penetrates into mucosa and sucks blood

GI tract bug:  Absorbs large quantities of Vit. B12

GU tract infxn is typically accomplished by

Properties of potential pathogen that allow it to establish within the host, avoid the host defenses and cause disease

Name 2 adherence factors

Proteins that promote tighter binding of bacteria to host.  Name 2 examples

Name 3 toxins

Typically heat labile, secreted into local environement: often A-B type (A has enzyme activity; often disrupts cAMP levels)

Inhibits release of neurotransmitters

Non-specifically bind to a conservatie region of T lymphocyte receptor

Name 5 diseases with superantigens

Endotoxin

Toxic component of LPS

Chelates iron, competes with transferrin

Inhibits C3b binding, inhibition of IFN activity, etc.

Elevated WBC:
Left-shift?
No shift?
Eosinophilia?

Common tests on dip stick for neutrophils

Not normally present in urine, but is produced by a # of bacterial species

Meningitis most common bacteria:
Neonates?
Children?
Adults?
Elderly?
Post-neurosurgery?

Name 2 stains done to check for CSF bacteria

Gram stain of male urethal discharge is senesitive/ specific for this, but NOT for females

Obtained from a chancroid, needs special media for culture

3 types of Urinary tract specimens

Only thing you refrigerate (and only if it takes more than 2 hours from collection to culture)

Feces sample bacteria:  Sensitive to drop in pH secondary to anaerobic metabolism, needs specific media

Feces sample bacteria:  Doesn't survive in buffered glycerol

Catalase Test

Certain organisms produce diffusible extracellular protein (CAMP factor) that works with beta-lysin of S. aureus to cause hemolysis

Performed to see if certain bacteria will use citrate as their sole carbon source and ammonium as sole nitrogen source

Allows transport of citrate into bacteria

Defense mechanism to clot surrounding plasma and resist phagocytosis.  This enzyme is produced by Staph.

Measures ability of microorganism to degrade tryptophan into indole, ammonia, and pyruvic acid.

Degradation of tryptophan is detected through addition of

Used to ID strains of strep pneumonia; has detergent-like action and causes selective lysis of pneumococci

Determines if organism possesses cytochrome c