Micro Lab Exam
Terms
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copy deck
- specimen is stained, so its image appears dark against a brigter background
- brightfield microscopy
- equal to the magnification of the objective multiplied by that of the ocular
- total magnification
- gathers light rays and focuses these on the object to be illuminated
- condenser
- an opaque disk with an adjustable aperture that by adjusting it one may improve on contrast of the image
- iris diaphragm
- light beams are deflected by different thicknesses of the object
- phase-contrast microscopy
- useful for direct observation of specimens that are not stained ex: protozoa
- phase-contrast microscopy
- specimen appears luminous against a background of little or no light
- dark-field microscopy
- used primarily to view spirochetes, which do not stain well and are too narrow to be observed by any other methods
- dark-field microscopy
- uses dyes known as fluorochromes that absorb ligh in the ultraviolet range, fluoresce, and then emit visible light of a greater wavelength
- fluorescent microscopy
- select and limit the wavelength of the transmitted light
- excitation filters
- transmits excited wavelengths to the objective
- dichromatic splitter
- longer wavelengths that are emitted pass through the ______ and the image fluoresces
- beam splitter
- a method to ensure the light microscope used is setup in such a way so as to provide the best sample illumination
- kohler illumination
- gram stain reagents
-
1) crystal violet
2) gram's iodine mordant
3) acetone/alcohol mixture
4) safranin - gram stain primary stain
- crystal violet
- gram stain mordant
- gram's iodine
- gram stain decolorizer
- acetone/alchol mixture
- gram stain counterstain
- safranin
- acid fast staining
- Ziehl-Neelsen
- acid fast reagents
-
1) carbolfuschsin
2) acid-alcohol mixture
3) methylene blue - acid fast primary stain
- carbolfuschsin
- acid fast decolorizer
- acid-alcohol mixture
- acid fast counterstain
- methylene blue
- acid-fast bacilli appear as...
- red aggregations against a blue background
- partial acid-fast staining
- Kinyoun
- In partial acid-fast staining what is used instead of heat to allow penetration of the stain into the cell wall?
- tergitol
- Kinyoun stain is used in detecting?
- Nocardia
- Partial acid-fast reagents
-
1) carbolfuchsin
2) acid-alcohol mixture
3) methylene blue - endospore staining reagents
-
1) malachite green
2) safranin - In endospore staining, endospores will appear ______ in color and vegetative cells will appear ______
- green; red
- culture media constructed completely from chemically defined components
- defined or synthetic media
- media may contain constituents like peptones and yeast extract whose precise composition is unknown
- complex media
- media that supports the growth of many non-fastidious microorganisms
- general purpose (nutrient media)
- media that supports and encourages the growth of fastidious bacteria
- enriched/fortified media
- media that favors the growth of particular microorganisms, while specifically inhibiting the growth of others
- selective media
- media that distinguish between different groups of bacteria and even permit tentative identification of microorganisms based on their biological characteristics
- differential media
- wide spread media used in isolation and identification of bacteria, combines the characteristics of both selective and differential media
- selective/differential media
- agar/broth used for cultivating Brucella and other fastidious microorganisms
- tryptose agar/broth
- used with blood in isolating, cultivating and determining the hemolytics reactions of fastidious microorganisms
- tryptose blood agar base
- the reduction of hemoglobin to methemoglobin in the medium surrounding the colony
- alpha/incomplete hemolysis
- causes a greenish discolorization of the medium
- alpha/incomplete hemolysis
- lysis of red blood cells resulting in a clear zone surrounding the colony
- beta/complete hemolysis
- no destruction of red blood cells occurs and there is no change in the medium
- gamma/no hemolysis
- a small zone of complete hemolysis that is surrounded by an area of partial lysis produced by staph aureus and clostridium perfringens
- alpha-prime/double zone hemolysis
- a selective and differential medium used for the isolation and differentiation of gram-positive microorganisms from clinical and nonclinical materials, supplemented with 5% sheep blood
- Columbia CNA agar with 5% sheep blood
- a medium consisting of colistin and nalidixic acid
- Columbia CNA agar
- Columbia CNA agar cultural response
-
gram-positive bacteria: typical hemolytics colonial morphology
gram-negative bacteria: no growth to trace growth - selective isolation of staphylococci from clinical and nonclinical materials
- mannitol salt agar
- mannitol salt agar selective chemical
- sodium chloride
- mannitol salt agar differential chemical
- mannitol
- mannitol salt agar pH indicator
- phenol red
- concentration of sodium chloride in mannitol salt agar
- 7.5%
- bacteria that that utilize mannitol in mannitol salt agar ______ the pH turning the phenol red ______
- decrease; yellow
- bacteria that do not use mannitol in mannitol salt agar _____ the ph turning the phenol red _______
- increase; bright pink
- used to differentiate Enterococci and Streptococcus bovis group from other Streptococci
- Bile Esculin Agar
- indicator of esculin hydrolysis and resulting esculetin formation
- ferric citrate
- used to inhibit gram-positive bacteria other than enterococci
- oxgall (bile salt)
- macconkey agar selective chemicals
- bile salts and crystal violet
- macconkey agar substrate
- lactose
- macconkey agar pH indicator
- neutral red
- used for isolating and differentiating lactosefermenting from lactose nonfermenting gram-negative enteric bacilli
- macconkey agar
- macconkey agar expected results
-
lactose fermenting oraganisms gros as pink to brick-red colonies with or without a zone of precipitated bile
lactose-nonfermenting organisms grow as colorless or clear colonies - higly selective/differential medium for the isolation of gram-negative enteric bacteria
- Eosin Methylene Blue (EMB) agar
- EMB agar selective chemicals
- Eosin Y and methylene blue dyes
- EMB agar pH indicators
- eosin y and methylene blue
- EMB agar differential substrate
- lactose
- EMB agar expected results
-
lactose-fermenter bacteria will form blu-black colonies with dark centers. E. coli will appear as dark purple colonies with green metallic sheen
non-lactose-fermenter bacteria will appear colorless to translucent - highly selective/differential medium for the isolation of pathogenic enteric bacilli, especially those belonging to the genus Salmonella
- Salmonella Shigella (SS) agar
- SS agar selective chemical
- bile salts and brilliant green dye
- SS agar differential substrate
- lactose
- SS agar pH indicator
- neutral red
- SS agar sulfur source for H2S production
- sodium thiosulfate
- H2S indicator
- ferric citrate
- SS agar expected results
-
lactose-fermenter bacteria will form pink to red colonies
non-lactose-fermenter bacteria will form colorless colonies
H2S-producing bacteria will have black centered colonies of ferric sulfide - small group of bacteria killed by normal atmospheric levels of oxygen, but yet require traces of oxygen to grow
- microaerophiles
- terminal electron acceptor in aerobic respiration
- oxygen
- terminal electron acceptor in anaerobic respiration
- NO3, SO4, CO2 or fumarate
- terminal electron acceptor in fermentation
- organic compound
- bacterial cells with a single flagellum
- monotrichous
- single flagellum at one end of a rod-shaped cell
- polar flagellum
- bacteria with a single tuft of flagella
- lophotrichous
- bacteria with tufts of flagella at both ends of the cell
- amphitrichous
- bacteria that are covered all over in flagella
- peritrichous
- special dye added to motility test medium to make the radiating growth more visible as the reddish diffuse area
- tetrazolium salt (TTC)
- determines the atmospheric requirement of a bacterium, whether a bacterium is oxidatively or fermentatively using glucose
- O/F glucose media
- O/F glucose media contains how much glucose
- 1%
- O/F glucose media pH indicator
- bromothymol blue
- Bromothymol blue is what color at low pH
- yellow
- bromothymol blue is what color at high pH
- blue
- O/F glucose media interpretation
-
both tubes ar acidic (yellow): the organism is faculative anaerobe (fermentative)
only open tube is acidic: the organism is an obligate aerobe (oxidative)
no color change in both tubes: the organism is asaccharolytic - used to identify bacteria containing the respiratory enzyme cytochrome oxidase
- Oxidase test
- Enterobacteriaceae is oxidase...
- negative
- Pseudomonadaceae is oxidase...
- positive
- Oxidase test interpretation
-
Oxidase positive: smear will turn purple within 20-30 sec
Oxidase negative: smear will not turn purple within 20-30 sec - test the presence of the enzyme catalase
- catlase test
- Catalase test reagent
- hydrogen peroxide
- catalase test interpretation
- if the bacteria in question produce catalase, gas bubbles form and this is indicative of a positive test
- determines the ability of an organism to ferment a specific carbohydrate incoporated in a basal medium and produce acid or acid with visible gas
- carbohydrate fermentation tests
- All enterobacteriacae are or are not glucose fermenters
- are
- carbohydrate fermentation test pH indicator
- phenol red
- carbohydrate test interpretation
-
positive carbohydrate reaction: acid by products lead to decreased pH causing the phenol red to change from pink to yellow, inverted Durham tube in glucose broth is used to collect any gas produced
negative carbohydrate reaction: the utilization of proteins in the medium increases pH causing the phenol red to change to a darker red color - determines the ability of an organism to attack specific carbohydrates incorporated in a basal growth medium with or without the production of gas along with the determination of possible H2S production
- Triple Sugar Iron (TSI) agar tests
- concentrations of the carbohydrate in TSI
-
glucose: 0.1%
lactose: 1.0%
sucrose: 1.0% - TSI interpretation
-
Red/Yellow[alkaline/acid]K/A: bacterium is facultative anaerobe, saccharolytic and utilizes glucose only
Yellow/Yellow[acid/acid]A/A or A/A+G: bacterium is facultative anaerob, saccharolytics, and utilizes glucose, lactose and/or sucrose, the presence of bubbles or cracking is indicative of gas production
black precipitation: if an organism can produce H2S gas the gas will react with the iron to from iron sulfide which apppears as a black precipitate
Red/No change[alkaline/alkaline] K/N: organism failed to ferment glucose and is strictly aerobic - broth which contains .5% glucose and pH indicator
- MR/VP medium
- tests the ability of an organism to produce and maintain stable acid end products from glucose fermentation and to overcome the buffering capacity of the system
- methyl red test
- What does IMViC stand for?
- Indole, Methyl Red, Voges-Proskauer, Citrate
- when glucose is fermented through mixed acid pathways the pH is lowered below _____ and produces a positive methyl red test
- 4.4
- methyl red test interpretation
-
MR positive: the culture is sufficiently acid to allow the methyl red reagent to remain a distinct, stable, bright red color at the surface of the medium
MR negative: yellow culture at the surface of the medium
Delayed reaction: reddish orange color indicates organisms produce less acid from test substrate - determines the ability of some organisms to produce a neutral end product, acetylmethylcarbinol (AMC, acetoin) from glucose fermentation
- Voges-Proskauer (VP) test
- VP-I reagent
- alpha naphthol + KOH
- VP-II reagent
- creatine
- determines if an organism is capable of utilizing citrate as the sole source of carbon for the metabolism growth
- citrate test
- citrate substrate
- sodium citrate
- citrate source of nitrogen
- ammonium salts
- citrate pH indicator
- bromothymol blue
- citrate test interpretation
-
Positive reaction: growth with an intense blue color
Negative: no growth and no change in color (green) - determines the ability of an organism to split indole from tryptophan
- indole test
- indole substrate
- tryptophan
- indole product
- indole
- indole reagent
- Kovac's reagent
- indole test interpretation
-
positive reaction: bacteria produce a red layer following addition of Kovac's reagent
negative reaction: bacteria fail to produce a red layer following addition of Kovacs' reagent - detection of lysine decarboxylase (LDC), lysine deaminase (LDA), and/or hydrogen sulfide production for the identification of Enterobacteriaceae
- Lysine iron agar
- LIA substrate
- the amino acid lysine and a small amount of glucose
- LIA pH indicator
- bromocresol purple
- LIA source of sulfur
- sodium thiosulfate
- LIA H2S indicator
- ferric ammonium citrate
- LIA interpretation
-
purple slant/purple butt: LDA negative, LDC positive
purple slant/yellow butt: LDA negative, LDC negative, decrease in pH
port wine slant/ yellow butt: LDA positive decrease in pH, LDC negative decrease in pH
black precipitation: hyrdogen sulfide production - determines the ability of an organism to reduce nitrate to nitrites or free nitrogen gas
- nitrate reductase test
- nitrate substrate
- potassium nitrate
- nitrate product
- nitrite salts
- nitrate reagents
-
nitrate a: sulfanilic acid
nitrate b: alpha-naphthylamine - novobiocin sensitivity interpretation
- all staph species except staph saprophyticus are susceptible
- optochin sensitivity test
- differentiates between strep pneumonia and other alpha hemolytic strep
- bacitracin sensitivity test
- differentiates between strep pyogenes and other beta hemolytic strep
- What is the biochemistry involved with bacitracin?
- Inhibits bacterial cell wall synthesis
- Determines an organism's ability to produce and elaborate the CAMP factor
- CAMP test
- CAMP test
- differentiates and presumptively identifies human or animal strains of group B Streptococcus agalactiae from other Streptococcus spp.
- gram negative rods that do not produce spores
- Family enterobacteriaceae
- Family entero are oxidase positive or negative
- negative
- family entero have what kind of flagella
- peritrichous
- what species in family entero are non motile
- klebsiella and shigella
- primary pathogens of the family entero
- shigella, salmonella, yersinia, e. coli, klebsiella pneumoniae
- opportunistic pathogens of entero
- e. coli, klebsiella pneumoniae, proteus, serratia, enterobacter, morganella, providencia
- Who devised the orginal classification system for entero
- Edwards and Ewing
- antigen binding sites found ont he antibodies
- epitopes
- capsule antigen
- K antigen
- flagella antigen
- H antigen
- polysaccharide side chain of endotoxin of LPS
- O or somatic antigen
- enterohemorrhagic e. coli
- somatic(O), Flagellar(H), and/or capsular(K)
- enteroinvasive e. coli
- O, H, K
- enteropathogenic e. coli
- O, H, K
- enterotoxigenic e. coli
- Fimbrial(F)
- Salmonella pathotypes
- O, H, Virulence(Vi)
- agar used for Kirby-Bauer Disk-diffusion method
-
mueller-hinton or mueller-hinton blood
ph 7.2-7.4 - what is used to standardize the inoculum density
- BaSO4