Exam 3 Part 2 Flashcards
reactions that use water to split complex molecules
hydrolysis
these catalyze reactions inside cells
intracellular enzymes
these catalyze reactions outside cell
extracellular enzymes or exoenzymes
what identify extracellular enzymes
starch agar, DNase agar, tributyrin agar, milk agar
exoenzyme that liquifies solid medium
gelatinase
polysaccharide made up of < D glucose subunits
starch
starch is either
linear (amylose) or branched (amylopectin)
is starch large
yes too big to pass through membrane so must be split into individual glucose molecules
what does starch agar contain
beef extract, soluble starch, and agar
what is used to detect presence or absence of starch in vicinity around the bacterial growth
reagent iodine
what does a clearing around growth on starch agar mean
< amylase and or oligo-1, 6 glucosidase is present so positive result
what does no clearing around growth on starch agar mean
< amylase and or oligo-1 6 glucosidase is NOT present so negative result
what does Columbia CNA allow growth of and what does it inhibit growth of
allows growth of gram positive and inhibits growth of gram negative
what is Columbia CNA composed of
casein, digest of animal tissue, beef extract, yeast extract, corn starch, and sheep blood
what do the yeast and blood of columbia CNA do
yeast provides vitamins and blood supplies heme
what is selective against gram negative in Columbia CNA
antibiotic colistin and nalidixic acid
what does sheep blood make possible
differentiation of gram positive organisms based on hemolytic reaction
what is Columbia CNA agar used to isolate
Staphylococci, streptococci, and enterococci
what does poor or no growth on columbia CNA mean
inhibited by colistin and nalidixic acid so gram negative
what does good growth with clearing on columbia CNA mean
not inhibited by colisitn and nalidixic acid and completely hemolyzes RBCs so B hemolytic
what does good growth with greening on columbia CNA mean
not inhibited by colisitn and nalidixic acid and partially hemolyzes RBCs so < hemolytic
what does good growth with no color change on columbia CNA mean
not inhibited by colisitn and nalidixic and does NOT hemolyze RBCs so y hemolytic
what does mannitol salt agar contain
carbohydrate mannitol, 7.5 % sodium chloride, and pH indicator phenol red
when is phenol red different colors
yellow below 6.8, red 7.4-8.4 and pink above 8.4
what does the mannitol in salt agar do
provides the substrate for fermentation and makes the medium differential
what does the sodium chloride in mannitol salt agar do
makes medium selective as it kills most
what bacteria thrive on mannitol salt agar
Staphylococci
this indicates if fermentation with acid end products occured
phenol red
mannitol salt agar is used for
isolation and differentiation of staphylococcus aureus from other staphylococcus species
poor or no growth on mannitol salt agar
inhibited by NaCl so not staphylococcus
good growth on mannitol salt agar
not inhibited by NaCl so staphylococcus
yellow or halo on mannitol salt agar
produces acid from mannitol fermentation so pathogenic staphylococcus aureus
red growth and no halo on mannitol salt agar
does not ferment mannitol so staphylococcus but NOT aureus
what is another name for Eosin Mthyene Blue
Levine
what does EMB contain
digest of gelatin, lactose, and dyes esoin y and methylene blue
what does digest of gelatin provide EMB
organic carbon and nitrogen
what are the purposes of eosin y and methylene blue
1) inhibit growth of most gram positive
2) react with vigorous lactose fermenters whose acid end products turn growth purple/black
dark growth and green metallic sheen is typical of what on EMB
E. coli
what is EMB used for isolation of
fecal coliforms
poor or no growth on EMB
inhibited by dyes so gram positive
good growth on EMB
not inhibited by dyes so gram negative
pink/mucoid growth on EMB
ferments lactose with little acid production so possible coliform
dark growth on EMB
ferments lactose and or sucrose with acid production so probable coliform
colorless growth on EMB
does not ferment lactose or sucrose so noncoliform
what is blood agar useful for detecting
detecting hemolytic ability of gram positive cocci
this is produced by some gram positive cocci
exotoxins that destroy RBCs and hemoglobin
hemolysins
what does blood agar contain
5% blood in tryptic soy agar base
what is B hemolysis
complete destruction of RBCs and hemoglobin
results in clearing of medium around colonies
what is < hemolysis
partial destruction of RBCs and hemoglobin
produces greenish decolorization of agar around colonies
what is y hemolysis
nonhemolysis, appears as simple growth
no change to medium
hemolysins produced by steptococci
streptolysins
streptolysin O
oxygen liable (optimal is anaerobic conditions)
streptolysin S
oxygen stable(optimal under anaerobic conditions)
what technique is used for blood agar
streak and stab for isolation and encourage activity
what is the 21st test of api 20 E
oxidase test
what is the seven digit code interpreted on
analytic profile index
what is the 21st test of api 20 E
oxidase test
what is the seven digit code interpreted on
analytic profile index
what is api 20 E multi test system used for
clinically for rapid identification of Enterobacteriaceae and other gram negative rods
what is the purpose of the water in api 20 E
humidify the strip during inoculation
describe coliforms
rod shaped, gram negative non spore forming ferment lactose with production of acid/gas indicator of sanitary food quality example is E. coli
