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Microbiology Gram-negative rods: Enterobacteriaceae Part III Karen Honeycutt, M.Ed., MT(ASCP)SM MT 418 Clinical Microbiology Student Laboratory Session
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Microbiology Isolation Growth on BAP at 24 hrs, ambient air, CO 2 or anaerobically (facultative anaerobe) In general colony morphology: large, gray, beta- or nonhemolytic (normally larger than Staph, Strep, & Enterococci) GNR: Enterobacteriaceae
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Microbiology Characteristics Utilization of glucose (OF Glucose): GNR: Enterobacteriaceae
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Microbiology Characteristics Oxidase reaction: GNR: Enterobacteriaceae
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Microbiology Characteristics GNR: Enterobacteriaceae Growth on MAC: Yes
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Microbiology Characteristics GNR: Enterobacteriaceae Nitrate reduction: NO 3 to NO 2
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Microbiology Characteristics GNR: Enterobacteriaceae Flagellar arrangement: peritrichous
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Microbiology Biochemicals – ONPG Rapid Lactose “F” requires permease enzyme ONPG similar to lactose, doesn’t require permease enzyme to enter the organism ONPG + beta-galactosidease = yellow color Slow lactose fermenter (appear as NLF on MAC, KIA, etc.) and Rapid lactose fermenter (appear as LF on MAC & KIA are POSITIVE GNR: Enterobacteriaceae
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Microbiology Nitrate to Nitrite to Nitrogen Gas Inoculate to media with nitrate Incubate test 18-24 hrs Add reagent Reagent reacts with nitrite to form red color. This reaction indicates: What did the work? GNR: Enterobacteriaceae NO 3 to NO 2 Organism
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Microbiology Biochemicals – Nitrate After nitrate rgt addition: Zinc will reduce nitrate to nitrite Add zinc dust What did the work? GNR: Enterobacteriaceae Zinc Therefore, the organism is:Nitrate negative
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Microbiology Biochemicals – Nitrate After nitrate rgt addition: Zinc will reduce nitrate to nitrite Add zinc dust What did the work? GNR: Enterobacteriaceae Organism reduced nitrate to nitrogen gas Therefore, the organism is:Nitrate positive
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Microbiology Identification – Categories Lactose “F” Lysine, phenyalalanine or tryptophane deaminase positive? Lactose NF & LDA/TDA/PDA negative GNR: Enterobacteriaceae
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Microbiology Identification GNR: Enterobacteriaceae Motile HE KIA LIA ODC Indole Salmonella sp.Identification =
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Microbiology Identification GNR: Enterobacteriaceae Indole CitrateLIA Motile ODC KIA Escherichia coliIdentification =
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Microbiology Identification GNR: Enterobacteriaceae Indole ODC MacConkey KIA LIA Urea Proteus vulgarisIdentification =
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