Chapter 13 Bacteriology - Rodriguez

basic dye

commonly used; cationic dyes with positively charged groups that adhere to negatively charged molecules like nucleic acids and proteins

methylene blue, carbol fuschin, crystal violet, safranin, malachite green

examples of basic dye

acidic dyes

anionic dyes with negatively charged groups that bind to positively charged cell structures

eosin, rose bengal, acid fuschin

examples of acidic dyes

simple staining

single stain is used; directed towards coloring the forms and shapes of cells

differential staining

divides bacteria into separate groups; directed towards coloring the components of cells

105 CFU/mL

inoculum size in simple and differential staining

application of primary stain

application of mordant

application of decolorizing agent

application of secondary stain

steps in differential stain

gram stain

most commonly used differential staining

crystal violet

primary stain in gram staining

acetone alcohol

decolorizing agent in gram stain

iodine

mordant used in gram staining

safranin

secondary stain used in gram staining

decolorization

important step in gram staining

purple

gram positive color in gram staining

red/pink

gram negative color in gram staining

staphylococcus aureus, escherichia coli

quality control for gram staining

neisseria, veillonella, moraxella

all cocci are gram-positive except

removal of MgRNA

aged, dying, and autolyzing cells

by using acidic iodine during staining

due to technical error or wrong use of stains

reasons why gram-positive become gram-negative

chlamydia, mycoplasma, ureaplasma, spirochete

exceptions in gram staining

gram sure

differentiate gram-positive bacilli or coccobacilli from gram-negative rods or gram-variable; used as an adjunct staining procedure

blue fluorescence

positive result in gram sure staining

acid-fast staining

applied to bacteria with high lipid content in their cell walls

carbol fuschin

primary stain for AFB

heat

mordant used in Ziehl-neelsen (hot)

tergitol

mordant used in Kinyoun’s (cold)

3% acid-alcohol

decolorizing agent for AFB

methylene blue

secondary stain used in AFB

pappenheim method

differentiates mycobacterium smegmatis from mycobacterium tuberculosis

baumgarten method

differentiates mycobacterium leprae from mycobacterium tuberculosis

auramine-rhodamine method

selective for the cell wall of AFB

mycobacterium tuberculosis, nocardia asteroides, escherichia coli

quality control of AFB

colonial age, medium for growth, ultraviolet light

acid-fastness is influenced by

modified kinyoun

useful for identification of intestinal coccidian oocysts; ideal for the detection of cryptosporidia and cyclospora parasites in stool sample

negative staining

demonstrate the presence of a diffuse capsule surrounding some bacteria; for studying bacterial gas vacuole and viral morphology; bacteria appear as light-colored bodies against a dark background

fluorescent staining

utilizes special dyes to visualize bacterial cells; preferred for mycobacteria; has the ability to stain nucleic acid aside from protein contents of organisms

fluorochrome staining

used a single fluorescent dye and directed towards staining the bacterial cell; more sensitive than the routine differential staining; enhances the microscopy property of the organisms and provides greater contrasting power

acridine orange

nonspecific dye which binds to the nucleic acid component

bright orange fluorescence

positive staining reaction for acridine orange

auramine-rhodamine

stains the cell wall, specifically mycolic acid of mycobacteria

bright yellow or orange bacteria against a green background

positive reaction for auramine-rhodamine dye

immunofluorescence

involves use of a fluorescent dye and a specific antibody reagent to identify microorganism; it forms “tagging” between microbial antigen and conjugated antibody

fluorescein isothiocyanate

commonly used dye in immunofluorescence

apple green fluorescence

positive reaction for immunofluorescence

albert and neisser

metachromatic granules

anthony, hiss, and gin and nigrosin

capsule

dyar

cell wall

dorner and schaeffer-fulton

endospore

feulgen

DNA

fontana-tribondeau and levaditi

spirochetes

gray and leifson

flagella