BIOL41 Lab Exam3
Card Set Information
BIOL41 Lab Exam3
BIOL41 Lab Exam#3
What are the 3 genera of pathogenic cocci discussed?
Is Staphylococcus Gram positive or Gram negative?
2 species of Staphylococcus discussed
1) S. epidermidis
2) S. aureus
typically not pathogenic unless in blood stream
found on skin
causes opportunistic infections
1/3 of people are carriers
not always pathogenic
found on skin, mucus membranes
causes TSS (toxin mediated), cutaneous diseases
Are Streptococcus Gram positive or Gram negative?
Where is Streptococcus normally found?
Lancefield system of classification
classification of B-hemolytic Strep
in their cell walls
normally infect people
prototypical Group A Streptococcus
3 species of Strep discussed
1) S. pyogenes
2) S. pneumoniae
3) Enterococcus faecalis
can lead to Scarlet fever, strep throat, tonsilitis
lives in lungs
discussed in Strep group
looks like Strep, but chemically not
Are Neisseria Gram positive or negative?
Neisseria cell morphology/arrangement
typical human location of Neisseria
2 species of Neisseria discussed
1) N. gonorrhoeae
2) N. meningitidis
selective vs differential media
selective encourages/discourages growth of specific organisms
differential allows visual distinguishment between organisms
What type of medium is blood agar?
detects hemolytic ability of Gram(+) cocci
exotoxins that destroy red blood cells and hemoglobin
produced by several species of Gram(+) cocci
complete destruction of RBCs and hemoglobin
results in clearing of medium around colonies
partial destruction of RBCs
produces greenish discoloration of agar around colonies
appears as simple growth with NO change to the medium
What would you use PEA agar for?
isolating Gram(+) organisms
Is PEA selective, differential, or both?
only encourages growth of Gram(+) organisms
phenylethyl alcohol agar
alcohol breaks down Gram(-) membrane permeability barrier
mannitol salts agar
mannitol provides substrate for fermentation
high salt concentration
Is MSA selective, differential, or both?
: phenol red changes to yellow when pH<6.8
: high [NaCl] dehydrates/kills most bacteria
most staphylococci thrive but don't ferment
isolation/differentiation of S. aureus
bile esculin test
Group D strep test
broken down bile reacts with Fe and forms dark brown ppt
Is the bile esculin test selective, differential, or both?
: changes dark brown if esculin hydrolyzed
: organisms can tolerate bile
differentiates types of Staph that can/cannot clot plasma
made of plasma
typically used to differentiate S. aureus from other Gram(+) cocci
Why would an organism need coagulase?
Coagulase works in conjunction with normal plasma
components to form protective fibrin barriers around
individual bacterial cells or groups of cells, shielding
them from phagocytosis and other types of attack.
converts hydrogen peroxide into water and O
helps organisms live in environments with O
can identify aerobic and facultatively anaerobic bacteria that use oxygen as an electron acceptor
Staph. are catalase-positive
Strep. are catalase-negative
identifies presence of Cyt c oxidase
Neisseria is oxidase-positive
How do fungi obtain nutrients?
secrete exoenzymes into environment, then absorb digested nutrients
fungus that decomposes dead organic matter
What are fungal cells made of?
2 major types of fungi
1) yeasts (unicellular)
2) molds (filamentous)
undifferentiated vegetative tissue
idividual fungal filaments
collective groups of hyphae
have both mold and yeast life cycle stages
ex: Candida albicans
How do yeasts typically reproduce?
sporangiospores vs conidiospores
sac vs no sac
pomegranate vs dandelion
budded cell of yeast
Where does Candida albicans normally live?
3) female urogenital tracts
Is C. albicans yeast or mold?
What kinds of mycoses does C. albicans cause?
thrush (mouth), vulvovaginitis (vagina), cutaneous cadidiasis (skin)
common in soil
conidiophores (no sac)
produces antibiotic penicillin
conidiophores (no sac)
spoils a lot of food
can cause zygomycosis
What characteristics are shared by all protozoa?
3) trophozoite and cyst stages
4) no cell wall
3 mechanisms by which protozoans can move
trophozoite vs cyst
: vegetative state; eating/reproducing/moving
: resting state; survives in adverse environments
Entamoeba histolytica (disease caused, how it moves, how it spreads)
amebiasis (amoebic dysentery)
fecal-oral contact or contaminated water
Balantidium coli (disease caused, how it moves, how it spreads)
cysts in sewage-contaminated water
Giardia lamblia (disease caused, how it moves, how it spreads)
giardiasis (persistent, blood diarrhea)
fecally contaminated water/food
Trichomonas vaginalis (disease caused, how it moves, how it spreads)
Plasmodium spp (disease caused, how it moves, how it spreads)
spreads through mosquitoes
Toxoplasma gondii (disease caused, how it moves, how it spreads)
ingestion of oocytes in feces
3 general types of parasitic helminths
1) cestodes (tapeworms)
2) trematodes (flukes)
3) nematodes (roundworms)
cestodes seen in class
head of the tapeworm that attaches to host
segment of tapeworm (cestode) that contains reproductive structures and/or eggs
migrate out of animal and are ingested by others
: Schistosoma mansoni
: hookworms, pinworms, Ascaris lumbricoides
Diplydium caninum (disease caused, host organism, how infected)
abdominal discomfort, indigestion
dogs, cats, children
ingestion of flea that ate proglottid
Echinococcus granulosus (disease caused, host organism, how infected)
cyst fluid can cause anaphylactic shock
carnivore (herbivore intermediary)
ingestion leads to cyst formation in organ
Ascaris lumbricoides (disease caused, host organism, how infected)
inflammation of organ, pneumonia, blockage/damage of organs
juveniles reside in lungs, coughed up and transported to GI tract to mature
Necator americanus (disease caused, host organism, how infected)
bloody diarrhea, anemia
juveniles penetrate skin, enter blood, travel to lungs; coughed up and transported to GI tract to mature