Bacti lab final

martinezdvm's version from 2015-11-10 23:39

Section 1

Question Answer
Triple Sugar Iron Agar (TSI) detectsability of an organism to ferment lactose, sucrose or glucose and its ability to produce hydrogen sulfide
TSI medium contains:1% lactose, 1% sucrose, 0.1% dextrose, iron salts, and phenol red as a pH indicator
If the TSI turns yellow...:bacteria ferments lactose and sucrose
If the TSI remains red...:bacteria uses only glucose
If the TSI has a yellow butt and a red slant w/ or without gas...: (most likely species)Salmonella or Proteus
If TSI has a black butt...:H2S PRODUCTION (Salmonella and proteus)
If TSI tube is all yellow (Both slant and butt) and no gas (no black):E. coli or Kleibsella
If both the Slant and the Butt are red + no gas production:Pseudomonas
Pausteurella has similar TSI to E. coli and Kleibsella, it is differentiated by:an absence of growth on McConkey agar
Kleibsella can be differentiated from E. Coli when:cultured (Kleib has mucoid colonies) and w/ the urease + citrate test
Proteus can be distinguished from Salmonella (when & how)when cultured (proteus has a swarming growth)

Section 2

Question Answer
Urease test helps todifferentiate bacteria which produce urease enzyme from those who don't
Positive result produces:a pink-red color
bacteria that test positive on urease are:Proteus & Kleibsiella
Negative results of the urease test:tube remains a light orange hue
BACT who test negative for the urease test: E. coli & Salmonella

Section 3

Question Answer
SIM medium detects what? (3 things)S- H2S gas formation I- Indole test M- Motility test
If a black metallic sulfide is formed, what does that tell u?there was H2S gas formation
If the SIM medium turned red after addition if Kovac's reagent?Indole was detected
If there was a generalized turbidity as opposed to growth only along the inoculation line (SIM)?Motile bacteria
Kovac's reagent is what color usually?Yellow, when it reacts w indole it turns red

Section 4

Question Answer
The oxidase test detects what?the absence or presence of cytochrome C oxidase enzyme
Describe what a positive oxidase test would look like:The test strip would turn purple w/i 20 seconds
Name a bacteria that is positive on the oxidase test:Pseudomonas
T or F: All enterobacteriaceae are oxidase NEGATIVETrue
Which bacteria are in the enterobacteriaceae family?E. coli, Kleibsiella, Salmonella, Shigella, Y. pestis

Section 5

Question Answer
Simmons Citrate test does what?it tests the ability of a bacteria to use citrate as the sole carbon source.
Simmons Citrate contains what as a reagent?bromo-thymol blue
Which bacteria test positive on Simmons Citrate test? Kleibsiella, Salmonella, Proteus mirabilis
Which bacteria test negative on the Simmons Citrate test? E. coli
Is the Simmons Citrate test good to differentiate Kleib from E. coli?fuck yeah!

Section 6

Question Answer
Modified preston agar is AKA?"Campy medium"
Modified Preston agar contains?Charcoal, ferrous sulfate & sodium pyruvate
What are the selective agents added to the Modified Preston Agar?Sodium Deosxycholate & Cefoperazone (inhibits grown of enteric bacteria) (the chocolate & the pear inhibit the enteric bacteria)
Appearance of Campy? Gram stain?Small, slender & curvy. Gram negative.
Cefoperazone inhibits which bacteria?Enteric bacteria such as E. coli, Proteus & Pseudomonas
Which bacteria is resistant to Cefoperazone?Campylobacter

Section 7

Question Answer
Which bacteria (from the lab) have predictable susceptibility (to a drug) and therefore do not require antibiotic susceptibility testing?Corynebacterium, Erysipelothrix, Bacillus (all susceptible to PENICILLIN) ("Corny Pigs Baking Penicillin" <--more for me guys)
Name the several types of assay for determining the susceptibility of a bacterium to an antibiotic:Broth dilution method, Agar dilution method, Disk Diffusion assay (KB method) & E test
Name the agar used in the Kirby Bauer method: Mueller Hinton agar
Kirby Baer is: (quantitative vs qualitative) Why?qualitative, results are placed in categories: Sensitive, Intermediate or Resistant
E test: describe how it is conducted.An E-test strip w/ a labeled gradient of antibiotic concentrations (high to low) is placed on the surface of the plate.
How do you interpret the MIC on an E- test?where the zone of inhibition touches the E-test strio is the MIC for the organism.
MIC determines?the lowest concentration of the drug at which the bacterium tested does not show visible growth.
E- test (quantitative vs qualitative)Quantitative test
T/F: urine is measure quantitatively true
What are the antibiotics on a Kirby Bauer?Gentamicin, Enrofloxacin, Penicillin, Ampicillin, Tetracycline, Cephalothin
Low MIC on an E test indicates?susceptibility of the organism
Bacteria most commonly involved in a UTI? (these are most frequent in dogs)E. coli, Staphylococcus, Streptococcus, Proteus, Kleibsiella, Pseudomonas, Leptospira
Urine should be stored at what temperature?4 degrees Celsius
Which is the only bacteria that does not grow on McConkey but causes UTI?Leptospira
Methods of urine collection from most contaminated to least contaminated:Free catch (always contaminated) > Catheter > Cytocentesis (never contaminated)

Section 8

Question Answer
A catalase test is detects:detecting the presence of enzyme catalase
T/F Catalase tests are only done on Gram +'sTrue, it helps to differentiate Staph from Strep
Which bacteria is + on the catalase test:staphylococcus
Which bacteria are catalase negs?Streptococcus
Presence of bubbling would indicate?A positive result

Section 9

Question Answer
Coagulase test is done which bacteria?ONLY STAPH
Purpose of coagulase test:differentiating b/w pathogenic and non-pathogenic strains of staph
Which speciess of staph are positives?S. aureus & intermedius
Which staph species are negatives?S. epidermidis

Section 10

Question Answer
Purple Agar test is used in (which bacteria)Staphylococcus
Purpose of the Purple Agar test?differentiating b/w pathogenic and non-pathogenic strains of staph
Describe S. aureus results on the purple agar test:S. aureus rapidly ferments maltose & changes medium + colonies to yellow
Which species of Staph gives off a weak or delayed reaction? S. intermedius
Which species of Staph gives off a deeper purple hue? (& is there fore a negative for maltose fermentation)S. hyicus
T/F: S. epidermidis is a positive on the Purple agar testtrue

Section 11

Question Answer
Purpose of Latex particle agglutination test:distinguish S. aureus from S. intermedius
Clumping on the latex particle indicates a _____ resultpositive
Which staph species is positive on the latex agglu test?
Sugar fermentation tests ares to:differentiate Streptococci
Positives in sugar fermentation indicate a ______ resultpositive
CAMP test used for:a presumptive ID of Streptococcus AGALACTIAE (we like to CAMP under A GALAXY)
How is the CAMP test conducted?A hemolytic staphylococcys is streaked across a BA plate and isolates of streptococci to be tested are streaked at right angles to the staph streake
A positive CAMP reaction (describe)Arrow head appearance (zone of complete/clear hemolysis)
Which staph species will test + on CAMP?only staph AGALACTIAE (helps to distinguish mastitis pathogen from S. uberis and dysgalactiae)