MMSC270 Lab- Quiz 3 Review

how will an organism appear on a TSI and MAC if it ferments sucrose and can ferment glucose, but does not ferment lactose?

A/A on TSI; clear on MAC

which species is most commonly associated with the development of a black precipitate in a TSI slant?

salmonella

on which medium is a kirby-bauer susceptibility test performed?

mueller hinton (MH)

an alkaline/acidic TSI slant would be indicated by which colors?

red/yellow

what is the full name of the MIC test?

minimum inhibitory concentration

HEA is designed to inhibit the growth of which organism species'?

streptococcus and staphylococcus

a TSI slant will present as what colors if the organism only fermented glucose?

red/yellow

an organism grows all the way up to the antimicrobial disc on a kirby-bauer test with no zone of inhibition, the researcher understands that this result should be recorded as what?

resistant

what concentration of glucose is in a TSI slant?

0.1%

what concentration of lactose is in a TSI slant?

1.0%

what concentration of sucrose is in a TSI slant?

1.0%

salmonella has a distinctive product when it ferments carbohydrates. which product indicates that salmonella has grown on a TSI slant?

H2S precipitate

what is the full name for HEA?

hektoen enteric agar

which term describe the lowest dilution of antibiotic that will inhibit growth of an organism?

minimum inhibitory concentration

what does a positive oxidase reaction look like on filter paper?

dark-purple color

what does a positive indole reaction look like on filter paper?

blue-green color

a dark-purple color resulting from an oxidase test indicates that the organism possesses which enzyme?

indophenol oxidase

a blue-green color resulting from an indole test indicates that the organism possesses which enzyme?

tryptophanase

if an organism is fermenting sucrose and possibly lactose, what color will the slant appear?

yellow

if an organism is fermenting glucose and possibly peptones, what color will the slant appear?

red

if a black precipitate was formed in a TSI slant, what color was the slant before the precipitate was formed?

yellow

what color indicates a positive reaction from a urea test?

pink

what color indicates a negative reaction to a urea test?

yellow

what finding indicates a positive result from a citrate test?

growth and blue slant

what finding indicates a negative result from a citrate test?

no growth and green slant

the presence of which enzyme is tested by the urea test?

urease

how would the researcher denote that the organism did not ferment any of the carbohydrates in the TSI media?

N

the citrate test tests the ability of the organism to utilize which two compounds?

citrate and ammonium

the citrate test contains which compounds as a pH indicator?

bromothymol blue

which finding indicates a positive MR test?

red

which finding indicates a negative MR test?

yellow

which finding indicates a positive VP test?

red

which finding indicates a negative VP test?

no color change or slight darkening

what kind of container is used to collect stool samples?

nonsterile

most gastrointestinal pathogens produce self-limiting loose watery stool, which pathogen is unique due to it's superinfective properties?

C. diff

patients with a weakened immune system or who have taken antimicrobials for a prolonged time are at higher risk of infection by which pathogen?

C. diff

true or false: C. diff is considered to be normal microbiota in healthy patients.

true

which media can be used to store stool samples is transportation to the lab is delayed?

cary blair

are stool samples streaked with a qualitative or quantitative technique?

qualitative

which ingredient makes HEA selective?

bile salts

which ingredients make HEA differential?

carbohydrates and H2S indicator

which pH indicator is present in HEA?

bromthymol blue

which of the antimicrobial susceptibility tests uses individual fixed concentrations of a drug on a paper disc?

kirby-bauer

which of the antimicrobial susceptibility tests uses multiple concentrations of drug in micro-titers with broth?

MIC

for which stool organism test does the researcher "stab the butt" of the agar?

TSI

for which stool organism test does the researcher avoid "stabbing the butt" of the agar, so not to alter the results of the test?

citrate