microbiology common gram positive tests

what is the CAMP test used for primarily?

to differentiate Streptococcus species

positive test result from CAMP test:

enhanced hemolysis is indicated by an arrowhead-shaped zone of beta-hemolysis at the junction of the two organisms

negative test result with the CAMP test:

no enhancement of hemolysis

quality control for CAMP test:

positive: Streptococcus Agalactiae

negative: Streptococcus Dysgalactiae or Pyogenes

center line: Staphylococcus Aureus

what does the catalase test determine?

if aerobic bacteria produces a specific enzyme

can the catalase test be used for gram negative testing too?

yes

positive test results for catalase test:

gas formation (bubbles)

negative test results from catalase test:

no gas formation (no bubbles)

strep. when running a catalase test:

gram positive, catalase negative

staph. when running catalase test:

gram negative, catalase positive

citrate plasma from what animal is used (most commonly) for a coagulase test?

rabbits

positive test result from a coagulase test:

the plasma coagulates and the coagulate is stable. it must not be dissolved upon stirring

negative test result from a coagulase test:

the plasma does not coagulate or if the coagulate is dissolved again upon stirring; a couple clumps are still negative

what is the coagulase test used for?

to distinguish between coagulase positive and coagulase positive and coagulase negative staphylococci

do we use the Voges- Proskauer + methyl red test for everything?

yes

what is the VP test used to determine?

if an organism produces acetyl-methyl carbinol from glucose fermentation.

positive test result from a VP test:

color change to pink

negative test result from a VP test:

no color change

positive test result from methyl red test:

color change to red

negative test result from methyl red test:

color remains yellow

what does the methyl red (MR) test detect?

the production of sufficient acid during the fermentation of glucose and the maintenance of conditions

what is a kliglers agar used for?

to differentiate organisms by demonstrating hydrogen sulfide production and the fermentation of dextrose and lactose

carbohydrate fermentation with kliglers:

positive test for slant reaction: yellow (acid)

negative test for slant reaction: red (alkaline)

positive test for butt reaction: yellow (acid)

negative test for butt reaction: red (alkaline)

color reaction meaning with Kliglers test:

red slant/ yellow butt: dextrose (-), lactose (+)

yellow slant/ yellow butt: dextrose (+), lactose (+)

red slant/ red butt: dextrose (-), lactose (-)

hydrogen sulfide production results with Kliglers test:

positive test: black color throughout the medium

negative test: no black color development

gas production with Kliglers test:

positive test: bubbles in the medium, cracking and displacement of the medium, separation of the medium from the tube

negative test: no bubbles and no separation or displacement of the medium

what does the triple sugar slant test tell us its ability to ferment?

dextrose, lactose, and sucrose (along with the production of hydrogen sulfide)

do we use the triple sugar slant test for everything?

yes

an alkaline/acid (red slant/yellow butt reaction) for triple sugar slant test:

it is indicative of dextrose fermentation only

an acid/acid (yellow slant/ yellow butt) reaction with the triple sugar slant test:

it indicates the fermentation of dextrose, lactose and/or sucrose

an alkaline/ alkaline (red slant, red butt) reaction for triple sugar slant test:

absence of carbohydrate fermentation results

blackening of the medium for triple sugar slant test:

occurs in the presence of hydrogen sulfide

gas production reaction for triple sugar slant test:

bubbles or cracks in the agar indicates production of gas (formation of CO2 and hydrogen sulfide)

positive test result with urease/urea test:

magenta to bright pink color

negative test result with urease/urea test:

no color changes