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What are the 3 genera of pathogenic cocci discussed?
- 1) Staphylococcus
- 2) Streptococcus
- 3) Neisseria
Is Staphylococcus Gram positive or Gram negative?
2 species of Staphylococcus discussed
- 1) S. epidermidis
- 2) S. aureus
- Staphylococcus epidermidis
- typically not pathogenic unless in blood stream
- NOT hemolytic
- found on skin
causes opportunistic infections
- Staphylococcus aureus
- 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
- based on carbohydrates in their cell walls
- groups A-G normally infect people
prototypical Group A Streptococcus
3 species of Strep discussed
- 1) S. pyogenes
- 2) S. pneumoniae
- 3) Enterococcus faecalis
- Strep pyogenes
- can lead to Scarlet fever, strep throat, tonsilitis
- lives in lungs
- causes pneumonia
- 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?
- differential: phenol red changes to yellow when pH<6.8
- selective: 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
- isolate/differentiate enterococci
- broken down bile reacts with Fe and forms dark brown ppt
Is the bile esculin test selective, differential, or both?
- differential: changes dark brown if esculin hydrolyzed
- selective: 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 O2(g)
helps organisms live in environments with O2
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?
- asexual reproduction
- blastoconidia (buds)
sporangiospores vs conidiospores
sac vs no sac
pomegranate vs dandelion
budded cell of yeast
Where does Candida albicans normally live?
- 1) respiratory
- 2) GI
- 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
- sporangiophores (sac)
- can cause zygomycosis
What characteristics are shared by all protozoa?
- 1) unicellular
- 2) heterotrophic
- 3) trophozoite and cyst stages
- 4) no cell wall
- 5) eukaryotic
3 mechanisms by which protozoans can move
- 1) pseudopodia
- 2) cilia
- 3) flagella
trophozoite vs cyst
- trophozoite: vegetative state; eating/reproducing/moving
- cyst: 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)
- balantidiasis, dysentery
- 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)
- sexually transmitted
Plasmodium spp (disease caused, how it moves, how it spreads)
- gliding motility?
- spreads through mosquitoes
Toxoplasma gondii (disease caused, how it moves, how it spreads)
- gliding motility?
- ingestion of oocytes in feces
3 general types of parasitic helminths
- 1) cestodes (tapeworms)
- 2) trematodes (flukes)
- 3) nematodes (roundworms)
cestodes seen in class
- Dipylidium caninum
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
- ex: Schistosoma mansoni
- ex: 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