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30 Cards in this Set
- Front
- Back
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Simple stain
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consists of aqueous or alcohol solution of single basic dye.
methylene blue or crystal violet |
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Simple stain
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allow one to distinguish the shape, size, and arragnement of cells
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Differential stain
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use more than one stain and serve to differentiate among organisms or cellular components.
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Differential stain
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used to detect structural differences between bacterial
groups or provide contrast to diff. structures within same org |
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gram stain
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2 different dyes and 2 different reagents..CV-IODINE-ETOH-SAFRANIN
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purpose of gram stain
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differentiat bacteria into 2 large groups: gm pos. and gm neg.
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Gm stain
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when decolored cells retain primary stain based on differences in cell wall compositon.
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Gram postitive bacteria
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have thick layer of peptidoglycan in cell wall & retains CV/Iodine--appear blue
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Gram negative bacteria
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cell walls composed of thin layer of peptidoglycan & etoh soluble outer membrane. CV washes out. Safranin-pink
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Order of Gram Stain proceedure
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Crystal violet-primary stain
Iodine-mordent alcohol (rinsed with decolor) safranin (counterstain) |
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Viable Plate count
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direct method for evaluating the number of bacteria in a specimen
spread plate or pour plate |
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Plate count
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<30 or > 300 not considered significant.
countable plates 30-300. |
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Selective/Differential Media
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Medium that will inhibit the growth of some organisms but allow others to grow.
for GM+ bacteria |
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Mannitol Salt agar
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both selective/differential.Selects Staphlococci
inhibited by the salt. differentiates between path and non pathogenic |
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Mannitol salt agar test results
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pathogen ferments mannitol to produce acid end product which causes ph indicator in medium to turn from pink ot yellow
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Columbia colistin nalidixic acid agar (CNA)
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selective only. Gm+ cocci
colistin & nalidixic acid inhibit growth of Gm - organism and rods growth show + for Gm + cocci |
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TSA Blood Agar
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differential only. Has sheep Rbc. lysis occurs due to production of hemolysins by bacteria.
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categories of hemolysis in TSA Blood agar
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Beta -complete lysis, transparent clearing around colonies
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categories of hemolysis in TSA blood again
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Alpha partial hemolysis patial clearing (pale halo) around colonies and/or greenish discoloration
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categories of hemolysis in TSA blood again
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Gamma is used to indicate no hemolysis..
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Biochemical dtest media
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biochemical characteristic used to ID and differentiate bacteria.
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some biochemical test media that are useful to ID GM + bacteria.
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starch agar. Bile Esculin Agar.
Coagulase test. Catalase test |
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Starch Agar`
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media has starch.When iodine applied turns br/blk. Uncolored medium is + starch has been hydrolyzed-amylase present.
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Bile Esculin Agar
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meidum has esdulin and 40%bile.only bacteria that can grow in presence of bile will grow. blk/br + for Enterococ.
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Coagulase test
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media has rabbit plasma as reagent-LIquid. Detect enzyme in b.act.cells. Coagulates + for staph
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Catalase test
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uses hydrogen peroxide as a reagent. if catalase present in the cells of bacteria Bubbles + for catalase-
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Media test for Gram Negative Bacteria
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MacConkey agar
Hektoen Enteric (HE) agar |
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MacConkey agar
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both s/d. GM negative organisms. differentiates between coliform and non-colorrom.
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coliform species
MacConkey Agar |
ferment lactose to produce acid end products which causes ph indicator to make colonies a pink/red color
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Hektoen Enteric (HE) Agar
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both s/d.selects for Gm Neg organisms.differentiatesShigella& Salmonella & other GM neg. organisms.
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