Micro Lab Study Aid

Micro Lab Study Aid - L ab1Introduction Gramstaintechnique...

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Lab 1 Introduction Gram stain technique 1. crystal violet 2. iodine 3. acetone- alcohol unitl color disappears 4. safranin a. at each step rinse with water Staphylococcus- gram positive round bacteria/ cocci predominantly in pairs, tetrads, grape-like clusters Streptococcus gram positive round bacteria/cocci chains Strep pneumonia → shorter chains/ lancet-shaped diplococci Neisseria Gram negative Cocci in pairs kissing kidney beans” Bacillus gram positive large square ended-rods stain irregularly often indistinguishable from Clostridium by gram stain E coli gram negative rod bipolar staining sometimes present Rules of Thumb for Gram- staining properties of bacteria: 1. All cocci are Gram+ except: a. Genus Neisseria - aerobes b. Genus Veillonella- anaerobes c. Any nL Gm+ cocci which are aging or grown in acid environment can stain Gm – 2. Some rods are Gm- and some Gm+ 3. Some bacteria produce spores → usually impervious to most dyes => generally unstained when Gm stain a. Can be stained with malachite green b. 2 impt bateria that make spores: i. Clostridium spores look tennis-like rods ii. Bacillus 4. Some bacteria are acid-fast => cell walls have high conc of waxes and lipids a. 2 genera that are acid-fast i. Mycobacterium ii. Nocardia b. Use Ziehl-Neelsen stain Lab 2 Facultative Enteric Bacteria GP: illustrate EMB agar inhibits growth of GP: Enterococcus facecalis Gram stain: gram positive cocci in long and short chains Blood agar: gamma hemolysis, no lysis, shiny colonies EMB agar: no growth/ tiny little colonies Viridans Gram stain: gram positive elongated cocci, branched long chains Blood agar: alpha hemolysis, greeninsh, shiny silver tinlyl little colonies EMB: no colonies GN Rods Lactose Fermenters Ecoli gram stain: gram negative pink short squat rods blood agar: flowers, grayish colonies, white small clearing, beta hemolytic EMB agar: green sheen, lactose fermentation Oxidase test: negative K. pneum Gram stain: gram negatve short rods
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Micro Lab Study Aid - L ab1Introduction Gramstaintechnique...

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