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Bio 455 Lab Test 2
Milk, Viruses, UV light, Koch's Postulates, Tooth Decay, Enterics, Cocci, Epidemiology, Hand Washing
42
Microbiology
11/17/2009

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Term
EMB Plate
Definition
Selective for Gram Negative, Differential for bacteria that ferment lactose, E.coli appears as a green sheen
Term
SBA
Definition
Sheep Blood Agar. Enriched media, Differential for Alpha (incomplete), Beta (complete) and Gamma (none) hemolysis.
Term
Tellurite-Glycine Plate
Definition
Identifies coagulase-positive staphylococci. Contains peptones(nitrogen & AAs), yeast(nut), mannitol(carb), White media produces black colonies within 24 hours.
Term
DNase Plate
Definition
Teal agar plate detects presence of DNase. Presence of colorless zones is a positive result.
Term
Eugon (Luxuriant) Plates
Definition
White media used to grow fastidious organisms. Grows organisms used in Catalase test. Includes peptones (nitrogen, vit, AAs) dextrose (high energy source)Cystine & Sodium Sulfite (stimulate growth) NaCl (osmotic balance)
Term
Catalase Test
Definition
H2O2->H20+O2, observed by bubbles upon adding hydrogen peroxide. Staplylococci & Micrococci are positive. Streptococci & Enterococci are negative.
Term
Staphylococcus aureus
Definition
yellow/gold on SBA. Opportunistic pathogen--acne, boils, infections, food poisoning.
Gram +
Clusters
Strong Beta Hemolysis
Growth & Black Colonies on Tellurite Glycine
DNase +
Catalase +
Term
Staphylococcus epidermidis
Definition
White Colonies on SBA. Lesser virulent opportunistic pathogen.
Gram +
Clusters, dicocci, chains
Weak Beta hemolysis
Growth on Tellurite Glycine
DNase -
Catalase +
Term
Streptococcus pyogenes
Definition
Harmful upper repiratory infections & scarlet fever, strep throat, tonsillitis.
Gram +
Long Chains
Gamma Hemolysis
Tellurite Glycine -
DNase +
Catalase -
Term
Enterococcus faecalis
Definition
Lives in gut of mammals. Common pro-biotic. Non-motile, ferments lactose w/o gas production. Causes endocarditis, bladder, prostate infections. Becoming increasingly resistant.
Gram +
3-4 cell chains
Gamma Hemolysis
Growth @ 48 hours on Tellurite Glycine
DNase -
Catalase -
Term
Neisseria subflava
Definition
Inhabits mucus membrane of upper respiratory tract. Usually non-pathogenic.
Gram -
Dicocci
Gamma Hemolysis
Tellurite Glycine -
DNase -
Catalase +
Term
Sarcina lutea
Definition
mostly harmles saprophytes on dead organic matter. Yellow colonies.
Gram +
Packets (sarcina)
Gamma Hemolysis
Growth&Colonies @ 48hrs on Tellurite
Glycine
DNase -
Catalase +
Term
MBRT Test
Definition
Methylene Blue Reductase Test. Used to test milk quality. The Methylene Blue indicates presence of O2. If microorganisms are present, they will use up the O2 and the milk will not hold the blue color very long. <2 hrs=poor, 2-6hrs=fair, 6-8=good, >8hrs=excellent
Term
Koch's Postulates
Definition
1)Microbe must be present in ALL cases of the disease & absent in healthy individuals
2)Must be able to isolate the microbe and grow in pure culture
3)Same disease must result when healthy individual is infected
4)Must be able to isolate again from newly infected host
Term
Conjugation
Definition
The passage of plasmids between bacterial species.
Term
Plasmid
Definition
Extra-chromosomal circular DNA that encodes for non-essential but often beneficial traits such as resistance to antibiotics.
Term
Transformation
Definition
Uptake of free DNA from the environment. Possibly from other dead organisms.
Term
Transduction
Definition
Passage of genetic material between bacteria via phage (virus)
Term
Generalized Transduction
Definition
A lytic virus fails to dissolve all of the hosts DNA. While incorporating the viral DNA into its capsid before lysis, some of these DNA pieces get put in too. They are then transferred via phage into part of a new host's chromosome.
Term
Specialized Transduction
Definition
A lysogenic phage excises incorrectly and carries bits of host DNA on its ends. When the phage infects a new host, this DNA is incorporated. More efficient.
Term
Lytic Cycle
Definition
Virus attaches, inserts genome, makes enzymes that dissolve host DNA, uses viral genome to replicate and make protein capsids, packages them together and then lyses the cell.
Term
Lysogenic Cycle
Definition
Temperate phage attaches and inserts. It then incorporates its DNA into the host's DNA and remains dormant, replicating vertically. At some trigger, such as a weak immune system, it excises and enters the lytic cycle.
Term
Plaque
Definition
An empty spot on a bacteria lawn that indicates phages killed the cells.
Term
UV light experiment
Definition
UV can cause pyrimidine dimers in the DNA. Increased exposure increases DNA damage. The main repair mechanism is photolyase which requires light to activate. A dark repair process can occur in cases of extreme damage or when light isn't available. This method is much less effective.
Term
Plasmid Transfer Experiment
Definition
E. faecalis was studied. Each strain had one or more plasmid encoding for Tetracycline resistance, Conjunctive factor, or Streptomycin resistance. Conjunctive strains should be both Tet. and Strep. resistant. Plate on BHI (Brain Heart Infusion) because it contains Tetracycline and Streptomycin.
Term
Enterics
Definition
Gram negative bacilli found in the gut of animals and make up to 60% of fecal matter.
Term
Spirit Blue Plate
Definition
Tests for Lipase. Confirmed by forming colonies with halos.
Term
YLA plate
Definition
Yogurt Lactic Agar
Term
Skim Milk (Casein) plate
Definition
Used to detect the presence of proteases. Confirmed with clear halo around colonies.
Term
Spore Staining
Definition
Involves steaming the specimen while submerged in Malachite green to increase the spores permeability.
Term
Negative Staining
Definition
Uses India Ink to stain the background, leaving those bacteria with a capsule clear.
Term
PEA Plate
Definition
Phenylethyl Alcohol plate. Selective for Gram + bacteria by inhibiting DNA synthesis in Gram -
Term
Lophotrichous Bactera
Definition
Those with flagellum at one end.
Term
Starch Plate
Definition
Tests for Amylase.
Term
Peritrichous
Definition
Bacteria with flagella on all sides.
Term
Water Quality Test
Definition
Tests for coliforms.
1)Presumptive Test-Test for lactose fermentation by presence of bubbles and yellow color indicating reduced pH.
2)Confirmed Test-Streak on EMB plate to ensure that the bacteria is not Gram +
3)Isolate single colony from EMB and Streak on a NUT slant and innoculate the green bile tube. Look for turbidity, gas formation, Gram stain.
Term
Serratia marcescens
Definition
Red pigmented bacteria used in UV testing.
Term
Snyder Agar Test
Definition
Used to test for susceptibility to tooth decay. Contains glucose and the pH indicator bromcresol green. Bacteria will ferment glucose and produce lactic acid which will turn the indicator yellow.
Term
Simmons Citrate Agar slant
Definition
Selects for organisms that can use Citrate as sole carbon source and ammonium for nitrogen. Contains bromotymol blue to indicate pH (<6.9 is green; >7.6 is blue). In using the ammonium, the bacteria turn the solution basic therefore blue.
Term
Indole Test
Definition
Determines if bacteria can split tryptophan into indole aka Tryptophanase. Must be in sterile indole solution for 24 hours. Add Kovac's reagent after. Positive result is red/red violet color.
Term
MRVP tests
Definition
Methyl Red Voges-Proskauer tests. Initially in a broth that contaiins peptone, glucose, and phosphate buffer, some bacteria will ferment into just acetic acid, others into a variety of acids, and some not at all. Methyl Red shows that they fermented the mixed acids by being red in acidic environment. The VP test shows that it fermented only acetic acid because it will not overcome the buffer. Rather, will give a pH of roughly 6.2 Positive result is a maroon band that reacts with the acetic acid mixture.
Term
TSI slants
Definition
Triple Sugar Iron. Tests for those that ferment sugars and produce hydrogen sulfide. Differential media based upon ability to reduce sulfur and ferment carbohydrates. Judge by the position of color change whether it fermented glucose, lactose, or sucrose. If they reduce their terminal electron acceptor to sulfide, H2S reacts with the ferrous sulfate to form ferrous sulfide, black precipitate. If anaerobic microbes at the butt use H+ as terminal electron acceptor, they'll release gas, cracking the agar.