PRACTICAL Identification of unknown bacterium Why species level identification required? To know which species is involved in the particular condition To know the subspecies To further know the.
Download ReportTranscript PRACTICAL Identification of unknown bacterium Why species level identification required? To know which species is involved in the particular condition To know the subspecies To further know the.
PRACTICAL Identification of unknown bacterium Why species level identification required? To know which species is involved in the particular condition To know the subspecies To further know the types Immunotypes, serotypes, chemotypes etc Epidemiological studies Basic steps to follow Get a pure culture If pure culture is given proceed Slope is given Nutrient agar Blood agar If mixture is given Get pure culture Pure culture follow up-Day 1 Nutrient agar slant Gram stain Growth characteristics Catalase, oxidase Purity, Pigment Motility/after 4 hours from PW/BHI If pure, S/C (1) PW (2) NA (3) BA (4) Mac Pure culture follow up-Day 1 Blood agar slant Gram stain Growth characteristics oxidase Purity, Pigment Motility/after 4 hours from PW/BHI If pure, S/C (1) BHI (2) NA (3) BA (4) Mac First day – preliminary findings Growth characteristics Gram stain Catalase Oxidase Motility Presumptive follow up Gram Negative Rods Oxidase negative Catalase positive Motile/ Nonmotile One of the members of enterobacteriaceae Oxidase Positive Catalase Positive Motile Vibrio or Pseudomonas etc Members of enterobacteriaceae: oxidase Negative Escherichia Klebsiella Citrobacter Salmonella Shigella Proteus etc Non enterobacteriaceae Oxidase positive Vibrios Pseudomonas etc Members of enterobacteriaceae: oxidase Negative(example) LF (ONPG) Escherichia Klebsiella Citrobacter NLF Salmonella Shigella Proteus A gram negative rod on BA/Macconkey agars Non hemolytic, moist, irregular, flat, centrally raised, 3-5 mm colonies, Lactose fermenting, Flat,irregular centrally raised, moist 2-4 mm colonies Tests to read on second day •Check whether the culture is pure •Repeat catalase, oxidase,gram and motility to confirm previous day’s findings Biochemical tests TSI: A/A, Gas +, H2S Negative SIM: H2S,Neg, Indole: Positive., Motile Motility; (PW) Motile It could be ESCHERICHIA, CITROBACTER,OR ENTEROBACTER Glucose : Positive (Acid and Gas) Lactose : Positive Sucrose : Negative / Positive Mannitol : Positive Macconkey: LF Indole : Positive Gram: Gram Negative rods MR : Positive LAO : +-+ VP : Positive Melonate: - Citrate : Negative Urease : Negative Catalase: Positive Oxidase ; Negative One of the members of Enterobacteriaceae KCN ; _ So it is Escherichia coli For further details: Contact Jasmn98