ASCI 165 Exam 2

how are bacteria classified?

shape, stain, appendage

give 2 examples of shape (bacteria)

cocci, bacilli

give 2 examples of stain (bacteria)

Gram +, Gram -

Give 2 examples of appendage (bacteria)

flagella, cilia

what are the 2 pathogenic properties of bacteria?

invasiveness, toxigenicity

describe invasiveness (bacteria)

ability to invade tissue

describe toxigenicity (bacteria)

endotoxin, exotoxin

describe endotoxins

toxin is within the cell wall and therefore released upon death of cell, released by Gram- bacteria

describe exotoxin

always being released, released by Gram+ bacteria

what are the general characteristics of viruses?

infectious agents with both living and nonliving characteristics, reproduce at high rates in living cells, can mutate, are acellular, only use host cell machinery, have DNA or RNA but not both

list the parts of the basic viral structure

genome, capsid, capsomeres, envelope

describe the genome

single or double strand DNA or RNA, but not both

describe the capsid

protein core surrounding the virus

describe the capsomeres

subunits of the capsid

describe the envelope

phospholipid bilayer from the host cell, contains viral proteins used to attach to host cell

how do viruses replicate?

viral attachment/ absorption to host cell > entry into host cell > movement to site of replication > replication within host > viral assembly/ maturation within host > viral release from host cell

list the different routs of infection for a virus

envelope, naked

what are the two ways of the envelope route of infection for a virus?

binding to cell membrane and viral capsid is released into cell, and endocytosis

what are the two ways of the naked route of infection for a virus?

attachment of capsid to cell membrane, then empty genetic info into cell, and receptor mediated endocytosis → endocytic vessicle

where does the local spread of a virus enter and exit the cell?

enters apical aspect > replicates > exits apical aspect

where does the hematogenous spread of a virus enter and exit the cell?

enters cell basally > replicates > exits apically and basally

which part of the Adaptive Immune System should respond to a viral infection?

cell mediated immunity

what are the characteristics of a prion?

a protein that is misfolded, body will not recognize it as foreign and something that needs to be fought off because the protein is self, can trigger normal proteins in the brain to misfold

characteristics of a prion disease

long incubation period (months to years), gradual increase in severity, no host immune response, typically not found till later

how are prions transmitted?

through contaminated neural tissue, placenta, eating grass or feed that was grown on infected land

what are some characteristics of mycoplasma?

atypical bacteria, no cell wall, no definitive shape

mycoplasma has a strong affinity for what in the body?

mucous membranes

name some of the places in the body where mycoplasma may cause an infection

respiratory tract, urogenital tract, mammary gland, joints

what does Chlamydia have an affinity for?

mucous membranes

how does Chlamydia reproduce?

inside of the cell by binary fusion

what to rickettsial infections require?

a vector (arthropod)

chlamydia and rickettsia are both known as _____ organisms

obligate intracellular

what is used to treat Chlamydia and rickettsia?

tetracycline

what are protozoa?

free living, single cell, eukaryotic cells with a cytoplasmic membrane, cellular organelles, and endoplasmic reticulum

how do protozoa avoid harsh environments?

secrete a protective coat and shrink into a round armored form called a cyst

for protozoa, which form is the infective stage?

cyst

what are some common protozoa?

giardia, coccidia, cryptosporidium, trichomonas, prioplasmosis, neospora, EPM

helminths are usually detected as _____ in the feces

eggs

what are the classifications of helminths?

nematodes, platyhelminthes

what are some examples of nematodes?

cooperia, parascaris, hemonchus

what are some examples of platyhelminthes?

trematodes, cestodes

what are the three major classes of anthelmintics?

Benzimdazoles, Macrocytic lactones, Pyrimidines

what is an example of benzimdazoles?

fenbenazole

what is an example of macrocytic lactones?

avermectin

what is an example of pyrimidines?

praziquantel

why is eprinomectin such a breakthrough in deworming programs?

does not pass through milk (useable on lactating diary cows without needing to discard milk)

why is rotating dewormers important?

worms can become resistant to drugs

why is long range so effective as a dewormer?

releases gradually after injection

what is an aflatoxin?

substances produced by fungi that may be extremely toxic to animals

what are characteristics of fungi?

eukaryotic cells, contain no chlorophyll, reproduce by spores, chitin or cellulose cell wall, thread-like bodies that usually branch

what are the forms for pathogenic fungi?

yeast, hyphae

what are the locations of mycotic infections?

superficial, subcutaneous, systemic, opportunistic

give an example of superficial

outer layers of skin or hair - ringworm

give an example of subcutaneous

subcutaneous tissue - gutteral pouch mycosis

give an example of systemic

deep tissue - Valley Fever

give an example of opportunistic

normal environmental fungi - antibiotic use

what are the forms that fungal infections can cause?

hypersensitivity, mycotoxicosis, ingestion of toxin, infection

describe hypersensitivity

allergic reaction to mold or spores

describe mycotoxicosis

aflatoxin poisoning from toxins produced by fungi

describe ingestion of toxin

poison mushroom

describe infection

primary and secondary

describe primary infection (form of fungal infections)

inhalation of coccidomycosis spores

describe secondary infection (form of fungal infections)

antibiotic use, after grain overload, increase in yeast production

give an example of hypersensitivity

COPD

give an example of mycotoxicosis

ergot poisoning

give an example of ingestion of toxin

consumption of a poison mushroom

give an example of infection

valley fever

how are fungal infections diagnosed?

there are many ways to diagnose because it depends on where the infection is: skin scrapings, tape impression, hypersensitivity, serology

why are fungal infections so hard to treat?

mammalian cells do not contain enzymes that will degrade cell calls made of cellulose or chitin and both fungi and animal cells are eukaryotic which makes it difficult for medications to select only fungus as the target

what drugs are used to treat fungal infections?

amphotericin B, azoles, griseofulvin, 5-fluorocytosine

what is the main difference between bacteria and viruses, concerning replication?

viruses reproduce at a high rate in living cells and use host cell machinery only, while bacteria can reproduce on their own through binary fission

what is the function of the capsule?

protects from phagocytosis, strong antigenic determinant

what is the function of the cell wall?

antigenic determinant

what are the components of a simple viral structure?

genome, capsid

what are the different genetic material possibilities for viruses?

DNA+-, DNA+, RNA+-, RNA-, RNA+, RNA+ retrovirus

which genetic material possibility for viruses can replicate the fastest and why?

RNA+: does not need to take as much time translating because it does not need to make a separate mRNA strand

what are two reasons as to why prions are impossible to treat?

no host immune response, non-inflammatory process in brain

which one is more likely to cause death in the animal before clinical signs: endotoxins or exotoxins?

exotoxins

what are the two unique characteristics for mycoplasma?

no cell wall, smallest known organisms capable of reproducing

how does Chlamydia replicate?

the elementary body enters the host cell, then becomes a reticulate body, then the reticulate body replicates by binary fission

what does Chlamydia need from the host to replicate?

ATP

name four common protozoa and indicate which system each infects

Giardia: GI

Coccidia: GI

Cryptocporidium: GI

Trichomonas: reproductive system

what is praziquantel used for?

treating cestodes

where can aflatoxin be found?

contaminated feed: silage, cereal grain

what is the most used class of drugs to treat fungal infections?

azoles

give two examples of azoles

fluconazole, miconazole

explain how grain overload can lead to a secondary mycotic infection

for ruminants, they need the intestinal wall of the rumen to be scratched by long-stem hay in order to work properly. Without this, the rumen will shut down, and the high protein in the grain will cause a drop in the rumen pH to a point of acidity

why are enveloped viruses difficult for the immune system to defeat?

they take its outer membrane from the host cell, then add viral proteins so it can leave by budding and evade immune defenses