Unit 1 Flashcards
Blood Agar: Selective/Differential?, Purpose, Contents
1) Differential
2) Determine hemolytic properties
3) -5% sheep blood
- trypticase soy agar base
- sodium chloride (ions support growth)
MacConkey Agar: Selective/Differential?, Purpose, Contents
1) Selective and Differential
2) Selects for gram negative lactose fermenting rods
3) -Bile salts to support GNB growth
- Crystal violet to inhibit GPCs
- Lactose and neutral red to allow for lactose fermenting GNBs to be easily distinguished b/c fermentation lowers the pH and neutral red causes the color change
Chocolate Agar: Selective/Differential?, Purpose, Contents
1) Nonselective
2) Recover Haemophilus and Neisseria species
3) -sheep blood
- Hemin
- Isovitalex Enrichment supplement
SXT Agar: Selective/Differential?, Purpose, Contents
1) Selective
2) Isolate Streptococcus pyogenes (Strep A)
* *Important b/c so much grows in throat
3) -Sulfamethoxazole and Trimethoprim inhibit GNBs and some GNCs
- Defibrinated sheep blood- Beta
CNA (PEA) Agar: Selective/Differential?, Purpose, Contents
1) Selective
2) Isolate Gram-positive organisms
3) -Sheep blood agar base
- Colistin and Naladixic-acid to inhibit gram-negatives
Campylobacter Agar: Selective/Differential?, Purpose, Contents
1) Selective
2) Recover Campylobacter jejuni
3) -Sheep blood base
- Peptones to supply nitrogenous compounds, carbon, sulfur and trace ingredients
- Yeast extract to provide B vitamins
- Dextrose/Glucose for energy sources
- Antimicrobial agents to inhibit all other bacterial growth
Hektoen Enteric Agar: Selective/Differential?, Purpose, Contents
1) Selective and Differential
2) Differentiate pathogenic from normal bacteria in stool samples b/c it inhibits gram positives and differentiates gram negatives (there are a lot in stool)
3) -Bile salts to support GNB growth
- Lactose, sucrose, and salicin to differentiate use of carbohydrate in different color colonies (orange=lactose)
- Acid fuchsin and bromthymol blue as pH indicators
- Ferric ammonium citrate and sodium thiosulfate medium to enable detection of hydrogen sulfide production (black)
Martin Lewis/Thayer Martin Agar: Selective/Differential?, Purpose, Contents
1) Selective
2) Recover Neisseria species
3) -GC base with casein and meat peptones
- phosphate buffer to maintain pH
- corn starch to neutralize toxic fatty acids that may be present in the agar
- Hemoglobin to provide hemin for growth
- Antimicrobial agents to inhibit GPC, GNBS, yeast and Proteus species
V or HBT Agar: Selective/Differential?, Purpose, Contents
1) Selective
2) Recover Gardnerella vaginalis
3) -CNA agar base
- peptones and yeast extract to supply B complex vitamins
- Human blood to enhance recovery
Thioglycerate Agar: Selective/Differential?, Purpose, Contents
1) Nonselective
2) Recover pathogens in low quantities or with difficult lab replicated growing conditions
3) -0.075% agar
- Thioglycolic acid to prevent the accumulation of peroxides which are lethal to some microorganisms
- Numerous nutrient factors to enhance all types of bacterial growth
Bacitracin:the principle, end product, purpose, quality control and possible test results
1)-Presumptive ID of Strep Group A
-Differentiate Staphylococcus from Micrococcus
2) Any zone of inhibition=sensitive
3) N/A
4) QC Positive: Streptococcus pyogenes
Negative: Streptococcus agalactiae
5) Sensitive: Strep A and Micrococcus
Resistant: Staphylococci
Optochin :the principle, end product, purpose, quality control and possible test results
1)-ID of Streptococcus pneumoniae
2) Zone of inhibition>/= 14 mm=sensitive
3)N/A
4)N/A
5) Sensitive: Streptococcus pneumoniae
Resistant: other α-hemolytic streptococci
Catalase test:the principle, end product, purpose, quality control and possible test results
1)-Differentiation of Staphylococcus species and Streptococcus species
2) Detects the presence of cytochrome enzymes
3) H2O and O2 causing bubbles
4) N/A
5) Positive: Staphylococcus
Negative: Streptococcus
Coagulase test (tube and slide methods):the principle, end product, purpose, quality control and possible test results
1) ID of S. aureus and Coag-negative Staph
2) Enzyme bound coagulase is known as clumping factor and normally converts fibrinogen into fibrin; SLIDE: Organism with fibrinogen + rabbit plasma = agglutination; TUBE: Free coagulase + rabbit plasma and 4 hour incubation = clot
3) Agglutination or clot
4) Slide method not a definiteive result if negativemust redo in tube for verification
5) Positive: S. aureus
Negative: Coag-negative Staph
CAMP test:the principle, end product, purpose, quality control and possible test results
1) -Presumptive ID of Group B Strep
2) Interaction between Step group B and S. aureus
3) “synergistic hemolysis”arrowhead shaped beta hemolyis
4) N/A
5) Positive=Group B strep
Cytochrome oxidase test:the principle, end product, purpose, quality control and possible test results
1) -ID Gram negative organisms
2) Dye is oxidized to form blue color
3) Blue color
4) N/A
5) Positive=blue
Bile esculin test:the principle, end product, purpose, quality control and possible test results
1) ID Strep group D, Enterococcus, Listeria
2) Bile salts inhospitable for many bacteria and utilization of esculin causes black color
3) Black color
4) N/A
5) ??
6.5% NaCl test:the principle, end product, purpose, quality control and possible test results
1) ID Strep group D from Enterococcus
2) Strep group D sensitive to high salt environment
3) Growth or no growth
4) Done in conjunction with BET
5) Positive= Enterococcus
Negative= Strep group D
??
Bile solubility test:the principle, end product, purpose, quality control and possible test results
1) ID of Streptococcus pneumoniae
2) Bile soluble organisms dissolve in the presence of 2% bile salt
3) Lysing/dissolving
4) Negative control: Streptococcus mitis
5) Positive= Streptococcus pneumoniae
ALA test:the principle, end product, purpose, quality control and possible test results
1) ID of Haemophilus species
2) Determine need for X factor
3) Growth if it doesn’t need X factor
4) N/A
5) Positive= does not require X factor
Negative= needs X factor, Haemophilus influenzae
X and V factor test:the principle, end product, purpose, quality control and possible test results
1) Differentiation of Haemophilus species
2) Determine need for X factor and V factor
3) Growth around whichever factor(s) is needed
4) N/A
5) Positive=needs that factor
PYR Test:the principle, end product, purpose, quality control and possible test results
1) ID of Enterococcus species
2) Color developer for catalase negative organism
3) Pink or no color
4) N/A
5) Positive (pink)= Enterococcus
Negative= Streptococcus
LAP Test:the principle, end product, purpose, quality control and possible test results
1) ID of Aerococcus species
2) Color developer for catalase negative organism
3)Red or no color
4) N/A
5) Positive (red)= Aerococcus
Negative= Streptococcus
Indole Production Test:the principle, end product, purpose, quality control and possible test results
1) ID of Gram negative organisms
2) Ability of organism to split tryptophan to form indole
3) Indole if positive in tube or on filter paper/disc
4) N/A
5) Positive=red/blue
