Quiz 5 Flashcards
What is the arrangement of Staph? What is it’s gram identification?
It is a gram + organism that is spherical (coccus) and arranged in clusters.
What does it mean for an organism to be catalase positive?
It means it has the enzyme (catalase) and can break down hydrogen peroxide (since it is toxic to them).
Which type of staph is common in the skin/nasal passage?
Staphylococcus aureus
Which types of staph are considered opportunisitic pahtogens?
Staph epi and Staph aureus
What does catalase do to hydrogen peroxide?
It converts it to water and oxygen.
What happens if we add hydrogen peroxide to an organism? How do we determine if it is positive or negative?
If the organism bubbles, it is positive
If the organism does not bubble, it is negative
Coagulase test is performed on what type of organisms?
Gram +, Catalase positive
What is coagulase?
It is an enzyme that binds to plasma fibrinogen and can cause “clotting”.
What is the purpose of coagulase test?
To help us identify Staph. aureus from other staphylococci
What is the DNAse test?
It is a test that helps us determine whether or not the organism produces Deoxyribonuclease (enzyme that alters DNA)
What media is used for DNAse test?
agar medium; DNase agar is a differential medium
What indicates a positive/negative result from DNAse test?
Positive: pink halo
Negative: clear halo
S.aureus is positive, S.epi is negative
What are the difference between Strep and Staph when considering catalase test?
Strep: Negative
Staphy: positive
What are the difference between Strep and Staph when considering Gram stain test?
Strep: positive cocci in cluster
Staph: positive cocci in chains
What are the difference between Strep and Staph when considering cellular respiration?
Strep: grows in low O2, high CO2 (anaerobes)
Staph: grows in high O2 (aerobe)
What are the difference between Strep and Staph when considering normal flora/pathogenic?
Strep: some pathogenic, some normal
Staph: almost all normal
What is SM110?
It is a selective medium that is used to isolate staphylococci and has a high concentration of NaCl
Is SM110 selective or differential?
Both because it is selective to gram + bacteria but also differential because different staph species will produce different results
What is MSA (Mannitol Salt Agar) ?
It a medium that is both selective and differential because it allows Staph to grow but differential because not all species can stand the high salt concentration.
What color does S.aureus form in MSA?
yellow
What color does S.epi produce in MSA?
No color change
What is a carrier?
It can be people that carry a pathogen without showing signs or symptoms of the illness and can transmit them to others
What is the main differences between S.epi and S. aureus?
S. aureus produces emolysin (enzyme that causes beta hemolysis)
S.epi does not produce any hemolysin
What is alpha hemolysis?
Incomplete/partial lysis of red blood cells
What is beta hemolysis?
Complete lysis of red blood cells
What is gamma hemolysis?
No lysis of the red blood cell
What do we use to detect the type of lysis in streptococcus species?
Blood Agar Plate (differential media)
Which type of hemolysis are normal? which are pathogenic?
Typically, alpha and gamma are normal, beta is mostly pathogenic
Which strep species causes dental plaque and cavities?
Strep. salivarius
Which strep causes dental caries (tooth decay)?
Strep. mutans
Why are candle jars important for incubating plates with strep?
Because andle jars are enriched and have high co2/low O2 concentrations.
What unit indicates evidence of a UTI?
> 100,000 bacteria
What is EMB agar?
a differential media used to isolate gram - bacteria
What microorganisms cause UTI’s?
E.coli, Proteus spp., Pseudomonas spp.
If dipstick is positive for glucose it means….
glucose is found in urine and possible diabetes in patient
If dipstick is positive for bilirubin it means…
Red blood cells are breaking down patient may have liver damage or disease
If dipstick is positive for Ketones it means…
Means there is excessive fatty acid breakdown and there may be issues between patient and diet (anorexia, diabetes, starvation)
If dipstick is positive for blood it means…
hemoglobin is present and can be early sign of kidney disease of urinary tract disease
If dipstick indicates pH is too high or low it means…
High pH: UTI
Low pH: emphysema, diabetic ketoacidosis, diarrhea
What pH is normal for urine?
4.6-8
If dipstick indicates positive for nitrite, it means…
Nitrite is in urine and indicates UTI
If dipstick indicates positive for leukocytes it means…
UTI is present becaue normal urine has no leukocytes
What is the main purpose of the reductase test?
To test the quality of milk
How does the reductase test work?
The removal of oxygen from milk will cause color to disappear. If the color disappears more quickly, it will indicate large numbers of bacteria
What chemical agent will be added to milk during reductase test?
Resazurin. It will go from blue/purple to pink and eventually colorless
How do we determine the number of bacteria in reductase test?
We can use the standard pour plate count method.
Certified raw milk cannot exceed _______ bacteria
10,000
Certified pasteurized milk cannot exceed _______ bacteria
500
Grade A raw milk cannot exceed ______ bacteria
100,000
Grade A pasteurized milk cannot exceed _________ bacteria
200,000
Which milk cannot be consumed?
industrial-grade milk
