BIOL41 Lab Exam3

• 1) Staphylococcus
• 2) Streptococcus
• 3) Neisseria

Gram positive

• 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
• hemolytic

causes TSS (toxin mediated), cutaneous diseases

Gram positive

respiratory tract

• classification of B-hemolytic Strep
• based on carbohydrates in their cell walls
• groups A-G normally infect people

S. pyogenes

• 1) S. pyogenes
• 2) S. pneumoniae
• 3) Enterococcus faecalis

• Strep pyogenes
• can lead to Scarlet fever, strep throat, tonsilitis
• B-hemolytic

• lives in lungs
• causes pneumonia

• discussed in Strep group
• looks like Strep, but chemically not

Gram negative

diplococci

mucous membranes

• 1) N. gonorrhoeae
• 2) N. meningitidis

• selective encourages/discourages growth of specific organisms
• differential allows visual distinguishment between organisms

• differential
• 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

• non-hemolysis
• appears as simple growth with NO change to the medium

isolating Gram(+) organisms

• selective
• 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

• 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 

• Group D strep test
• isolate/differentiate enterococci
• broken down bile reacts with Fe and forms dark brown ppt

• 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

• 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

fungal infection

secrete exoenzymes into environment, then absorb digested nutrients

fungus that decomposes dead organic matter

chitin (polysaccharide)

• 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

• asexual reproduction
• blastoconidia (buds)

sac vs no sac

pomegranate vs dandelion

budded cell of yeast

• 1) respiratory 
• 2) GI 
• 3) female urogenital tracts

dimorphic yeast

thrush (mouth), vulvovaginitis (vagina), cutaneous cadidiasis (skin)

• mold
• common in soil
• conidiophores (no sac)

• mold
• produces antibiotic penicillin
• conidiophores (no sac)

• mold
• spoils a lot of food
• sporangiophores (sac)
• can cause zygomycosis

• 1) unicellular
• 2) heterotrophic
• 3) trophozoite and cyst stages
• 4) no cell wall
• 5) eukaryotic

• 1) pseudopodia
• 2) cilia
• 3) flagella

• trophozoite: vegetative state; eating/reproducing/moving
• cyst: resting state; survives in adverse environments

• amebiasis (amoebic dysentery)
• pseudopodia
• fecal-oral contact or contaminated water

• balantidiasis, dysentery
• ciliate
• cysts in sewage-contaminated water

• giardiasis (persistent, blood diarrhea)
• flagellate
• fecally contaminated water/food

• trichomoniasis
• flagellate
• sexually transmitted

• malaria
• gliding motility?
• spreads through mosquitoes

• toxoplasmosis
• gliding motility?
• ingestion of oocytes in feces

• 1) cestodes (tapeworms)
• 2) trematodes (flukes)
• 3) nematodes (roundworms)

• Dipylidium caninum
• tapeworm

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

outer covering

• fluke
• ex: Schistosoma mansoni

• roundworm
• ex: hookworms, pinworms, Ascaris lumbricoides

• abdominal discomfort, indigestion
• dogs, cats, children
• ingestion of flea that ate proglottid

• cyst fluid can cause anaphylactic shock
• carnivore (herbivore intermediary)
• ingestion leads to cyst formation in organ

• inflammation of organ, pneumonia, blockage/damage of organs
• humans
• juveniles reside in lungs, coughed up and transported to GI tract to mature

• (hookworm)
• bloody diarrhea, anemia
• humans
• juveniles penetrate skin, enter blood, travel to lungs; coughed up and transported to GI tract to mature