laboratory-bacte

Page 1: Fermentation and Quality Control

• Organism Fermentation: Indicates production of acid gas (usually CO2 or H2).

• Quality Control:

  • Escherichia coli: K/A, 1/2 gas production, H2S+

  • Salmonella typhimurium: K/K, H2S+

  • Pseudomonas aeruginosa: K/A, H2S+

  • Proteus mirabilis: K/A

  • Shigella flexneri: K/A

• Gas Production Indication:

  • Lowercase (g): small amount

  • Uppercase (G): large amount

Page 2: Lysine Iron Agar Test

• Purpose: Differentiate gram-negative bacilli.

• Components: Lysine, peptones, glucose, ferric ammonium citrate, sodium thiosulfate.

• Principle: Acidic butt (yellow) from glucose fermentation; purple butt from decarboxylation of lysine.

• Method: Stab and streak method, incubate at 35-37°C.

• Expected Results: K/K: no fermentation; K/A: glucose fermentation; Black precipitate indicates H2S production.

Page 3: Triple Sugar Iron Agar Test

• Purpose: Determine fermentation of glucose, lactose or sucrose, and H2S production.

• Composition: 10 parts lactose, 10 parts sucrose, 1 part glucose.

• Results Interpretation:

  • K/NC: non-utilizer

  • K/A: glucose only

  • A/A: fermentation of all three sugars.

• H2S Detection: Black precipitate indicates reduction.

Page 4: Methyl Red and Voges-Proskauer Tests

• Methyl Red Test:

  • Purpose: Identify mixed acid fermentation.

  • Expected Result: Red positive; yellow negative.

  • Quality Control: E. coli (MR+) vs. Klebsiella (MR-).

• Voges-Proskauer Test:

  • Detects acetoin production; red positive result.

  • Quality Control: Klebsiella (VP+) vs. E. coli (VP-).

Page 5: Coagulase Test

• Slide Coagulase Test: Positive if clumping present.

• Tube Coagulase Test: Clot present indicates positivity.

• Quality Control: S. aureus (positive), S. epidermidis (negative).

Page 6: Indole Test

• Purpose: Identify tryptophanase producers.

• Method: Inoculate broth, add Kovac's reagent.

• Expected Results: Pink ring positive, no color change negative.

• Quality Control: E. coli (positive), K. pneumoniae (negative).

Page 7: Laboratory Learning Outcomes

• Discuss bacterial identification techniques and procedures for differentiation based on biochemical properties.

Page 8: Inoculation Techniques

• Types of inoculation techniques: stab only, streak only, and combination methods.

Page 9: Subculture Procedure

• Pick discrete colonies from an agar plate/slant and inoculate into a new culture.

Page 10: Pure Culture Isolation

• Techniques for isolation of pure cultures: streak-plate and pour-plate methods.

Page 11: Streak-Plate Techniques

• Learning and performing the four-quadrant streak technique for isolating discrete colonies.

Page 12: Flame Technique Illustration

• Visual instructions for proper flaming technique during inoculation.

Page 13: Isolation of Discrete Colonies

• Main technique is using streak-plate methods to ensure distance for colony isolation.

Page 14: Culture Transfer Techniques

• Proper transfer of cultures maintains sterility and prevents contamination.

Page 15: Laboratory Equipment and Usage

• Key equipment for microbiology, including incubators, autoclaves, and culture media types.

Page 16: Aseptic Techniques

• Importance of sterility and aseptic techniques in handling microorganisms.

Page 17: Bacterial Isolation and Cultivation Techniques

• Overview of objectives in isolating bacterial species for cultural characterization.

Page 18: Sulfide Indole Motility Test (SIM)

• Purpose: Differentiates sulfur-reducing, indole-producing, and motile bacteria.

• Expected Results: Black precipitate for H2S, pink ring for indole, diffuse growth for motility.

• Quality Control: Includes groups like Salmonella and Proteus for H2S.*