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Laboratory 7 & 8 Bacteriology

Laboratory 7 & 8 Bacteriology. Bacteria. Small Unicellular Organisms Can be grown in nutrient enriched environments (Agar, Broth) Standard Medias: Tryptic Soy Agar (TSA), Brain Heart Infusion (BHI), Tryptic Yeast Extract and Salt (TYES).

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Laboratory 7 & 8 Bacteriology

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  1. Laboratory 7 & 8Bacteriology

  2. Bacteria • Small Unicellular Organisms • Can be grown in nutrient enriched environments (Agar, Broth) • Standard Medias:Tryptic Soy Agar (TSA), Brain Heart Infusion (BHI), Tryptic Yeast Extract and Salt (TYES)

  3. Flavobacterium psychrophilum-Coldwater Disease-Gram Negative Rods Renibacterium salmoninarum-Bacterial Kidney Disease-Gram Positive Rod Yersinia Ruckeri-Enteric Red Mouth Disease-Gram Negative Rods Aeromonas salmonicida-Furunculosis-Gram Negative Rod Streptococcus iniae-O –sherical shape-Gram Postive Common Bacterial Fish Pathogens

  4. Aseptic Technique • Minimizes contamination from outside sources • Prevents work surfaces from becoming contaminated

  5. Bacterial Isolation • Streaking technique used to isolate individual bacterial colonies. • Can be used to isolate colonies in pure or mixed cultures

  6. Wet Mounts • Used to determine motility of organism • Can help in bacterial identification • Do not confuse with Brownian motion

  7. Bacterial Morphology • Colony Morphology • Size • Shape • Color

  8. Bacterial Morphology • Cell Morphology • Cocci • Bacillus • Spirochete

  9. Interpreting Antibiotic Sensitivity Test • Measure diameter of zone of inhibition (mm) • The larger the zone, the more effective an antibiotic will be.

  10. + - Gram Staining Heat Fixed • Gram positive organisms retain the primary stain • During decolorization gram negative organisms will lose pigment and pick up the counter stain Crystal Violet Gram’s Iodine Ethyl Alcohol Safranin

  11. Gram Staining Disadvantages: • Some bacteria are Gram stain variable (positive or negative results) • Some bacteria are resistant to Gram stain (i.e. acid-fast bacteria) • False results may occur if over-decolorized • Older cultures may give false results

  12. KOH (Potassium Hydroxide) Test • Alternative to Gram stain • Stringy and viscous = Gram negative • No viscous or stringy = Gram positive • KOH is caustic: wear gloves and immediately flush skin or eyes with water if they come into contact with KOH solution

  13. Cytochrome Oxidase Test • Identifies organisms that produce cytochrome oxidase • Solution remains colorless = negative (doesn’t produce cytochrome oxidase) • Solution turns purple or blue = positive (does produce cytochrome oxidase) • Results appear within 15 seconds

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