Term
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Definition
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Term
| Approximately how many people are healthy carriers of Staphylococcus aureus? |
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Definition
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Term
| How is Staphylococcus aureus transmitted? |
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Definition
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Term
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Definition
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Term
| Mannitol salt agar medium is selective for? |
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Definition
| isolation of staphylococci |
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Term
| Significant ingredients of Mannitol salt agar? |
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Definition
7.5% sodium chloride
mannitol
pH indicator phenol red |
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Term
| Why is mannitol salt agar medium selective for staphylococci? |
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Definition
Most microorganisms are inhibited by high salt.
Staphylococci can tolerate such concentrations |
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Term
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Definition
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Term
| Differential properties of Mannitol salt agar? |
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Definition
sugar mannitol as test substrate
pH indicator phenol red |
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Term
| If mannitol is not fermented |
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Definition
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Term
| What effect does Staphylococcus aureus have on mannitol salt agar? |
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Definition
| Ferments mannitol and the medium turns yellow |
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Term
| What effect does Staphylococcus epidermidis have on mannitol salt agar? |
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Definition
| Does not ferment mannitol, medium remains red |
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Term
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Definition
Alpha hemolysis/partial hemolysis
blood agar medium
streptococci |
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Term
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Definition
Beta hemolysis/ full hemolysis
blood agar plate
Streptococci |
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Term
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Definition
Gamma hemolysis/ no hemolysis
Blood agar plate
Streptococci |
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Term
| A convenient way to classify streptococci? |
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Definition
| Based on their hemolytic action |
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Term
| Alpha hemolysis is accompanied by? |
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Definition
| Green color around colonies |
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Term
| Another method of classifying Streptococci? |
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Definition
| based on antigenic characteristics |
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Term
| How did lancefield name serological groups of streptococci? |
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Definition
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Term
| Beta hemolytic streptococci of Lancefield group A |
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Definition
| cause 90% of acute streptococcal infections in humans |
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Term
| Lancefield group A beta hemolytic streptococci can be differentiated from other groups by? |
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Definition
| Suceptability to bacitracin. |
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Term
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Definition
| Paper filter with bacitracin is dropped onto a freshly seeded culture plate |
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Term
| Two genera of bacteria within gram positive cocci? |
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Definition
| Staphylococcus and Streptococcus |
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Term
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Definition
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Term
|
Definition
| hydrogen peroxide to form water and oxygen |
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Term
| Streptococci do not produce |
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Definition
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Term
| Differentiate between Staph and Strep by |
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Definition
characteristic arrangements in gram stain
catalase production |
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Term
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Definition
| Gram positive Staphylococcus |
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Term
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Definition
| Gram positive Streptococcus |
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Term
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Definition
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Term
| What is on the left?[image] |
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Definition
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Term
| what is on the right?[image] |
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Definition
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Term
| Areas that should normally be sterile? |
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Definition
| Larynx, trachea, bronchi, bronchioles, alveoli |
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Term
| what organisms are likely found in the throat? |
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Definition
| pneumococci, meningococci or Haemophilus influenzae |
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Term
| which organism is not classified in the lancefield grouping system? |
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Definition
| Alpha hemolytic Streptococcus pneumoniae (pneumococcus) |
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Term
| Streptococcus veridians are |
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Definition
| part of normal flora, NOT pneumococci |
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Term
| to distinguish Streptococcus veridians from pathogenic Streptococcus pneumoniae |
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Definition
| Optochin susceptibility test |
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Term
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Definition
a chemical that inhibits Streptococcus pneumoniae
no effect on veridians (normal flora) |
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Term
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Definition
| Filter paper disk susceptibility |
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Term
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Definition
| Bacitracin suceptibility test |
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Term
What is on the left?
[image] |
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Definition
Group A beta hemolytic
Streptococcus pneumoniae
Sensitive |
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Term
What is on the right?
[image] |
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Definition
Non-group A Beta hemolytic
Streptococcus viridans
Resistant |
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Term
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Definition
Pneumococcal pneumoniae
blood smear |
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Term
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Definition
Pneumococcal pneumoniae
Sputum smear |
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Term
| Staphylococcus aureus criteria |
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Definition
golden pigment
beta hemolysin
ferments sugar mannitol
produces enzyme coagulase |
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Term
| Staphylococcus epideridis |
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Definition
NO golden pigment
NO beta hemolysin
NO fermenting of sugar mannitol
NO production of enzyme coagulase |
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Term
| Staphylococcus aureus on MSA plate |
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Definition
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Term
| Staphylococcus epidermidis on MSA plate |
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Definition
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Term
|
Definition
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Term
|
Definition
Positive/ no movement
Staphylococcus aureus |
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Term
| what is on bottom?[image] |
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Definition
Negative/liquid
Staphylococcus epidermidis |
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Term
| Explain how Sodium chloride is selective for Mannitol Salt Agar |
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Definition
| High salt concentrations inhibit growth of most organisms, Staphylococcus can tolerate it. |
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Term
| Explain how Mannitol is differential for MSA |
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Definition
| Staphylococcus aureus ferments the sugar mannitol. |
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Term
| Explain how pH indicator phenol red is differential for MSA |
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Definition
| When Staphylococcus aureus ferments the sugar mannitol, it creates an acid byproduct, turning the color to yellow |
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Term
| Upon examination of a gram stained smear, you see gram positive cocci. You are not sure whether they are streptococci or staphylococci. Name an enzyme test that will help distinguish between the two genera |
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Definition
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Term
| Name the substrate, enzyme, and end-products used to differentiate staphylococcus and streptococcus |
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Definition
3% hydrogen peroxide
Catalase
Water and oxygen |
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Term
| You isolated a species of Staphylococcus from a patients specimen. List four criteria you could use to identify the species |
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Definition
Beta hemolysis
Coagulase production
Golden pigment
Mannitol fermentation |
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Term
| A gram positive ciccus that grows in chains in broth medium and produces beta hemolysis on blood agar most likely belongs to which genus? |
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Definition
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Term
| To identify the Lancefield group streptococcus belongs to, a disk susceptibility test is performed. Name the test. |
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Definition
| Bacitracin suceptibility test |
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Term
| Explain the rationale behind the Bacitracin suceptibility test |
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Definition
| Group A beta hemolytic growth is inhibited by bacitracin. Non-group A beta hemolytic is not. |
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Term
| A direct smear of a sputum specimen reveals gram-positive diplococci, many white blood cells, and mucus. You suspect the patient has... |
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Definition
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Term
| To confirm diagnosis of Streptococcus pneumoniae, a disk test can be performed, name the chemical in the test. |
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Definition
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Term
| Explain the rationale of the Optochin test |
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Definition
| Optochin inhibits growth of Streptococcus pneumoniae, not Streptococcus veridians |
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Term
Identify the organism:
Gram positive coccus, grape-like clusters, beta hemolytic on blood agar medium, ferments mannitol, produces coagulase |
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Definition
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Term
Identify the organism:
gram positive coccus, singles, pairs, and chains, beta hemolytic on blood agar medium, susceptible to bacitracin |
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Definition
| Group A beta hemolytic Streptococcus |
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Term
Identify the organism:
Gram positive diplococcus, alpha hemolytic on blood agar medium, susceptible to optochin |
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Definition
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Term
Identify the organism:
Gram positive cocci, nonhemmolytic on blood agar medium, produce the enzyme catalase, does not ferment mannitol, does not produce coagulase |
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Definition
| Staphylococcus epidermidis |
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Term
Identify the organism:
Gram positive cocci, lack the enzyme catalase, beta hemolytic on blood agar medium, resistant to antibiotic bacitracin |
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Definition
| Non-group A beta hemolytic streptococcus |
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Term
| Briefly describe what the enteric bacteria are and explain why biochemical tests are usually used to identify these bacteria |
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Definition
| Enteric bacteria are a diverse group of bacteria found in the GI considered as normal flora. We use biochemical tests to differentiate physiological differences and metabolism |
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Term
| What medium is used to detect fermentation of several sugars simultaneously? |
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Definition
| TSI (Triple Sugar Iron agar) |
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Term
| Name the sugars in TSI agar |
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Definition
| glucose, sucrose, lactose |
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Term
| What is the name of the pH indicator in TSI? |
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Definition
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Term
| What are the acid and alkaline colors in TSI? |
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Definition
Yellow/Acidic
no change/Alkaline |
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Term
| In addition to detecting sugar fermentation, what else can be detected using TSI? |
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Definition
| Hydrogen sulfide production (blackening) |
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Term
| What is the pH indicator used in Citrate test? |
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Definition
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Term
| What are the acid and alkaline colors in the citrate test? |
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Definition
Blue/ Alkaline
Green (yellow)/ Acidic |
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Term
| Explain the principle of the urea agar slant |
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Definition
| Alkalinization/production of ammonia changes color to pink/red |
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Term
| explain the principle of the motility test medium |
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Definition
| Stab medium, if it shows diffuse growth from stab line, its positive |
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Term
Interpret the results:
TSI slant: red slant/yellow deep, no bubbles or cracks |
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Definition
| Only one suger (glucose) fermented |
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Term
Interpret the reults:
Citrate slant: growth and blue |
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Definition
| Alkaline and positive for citrate utilization |
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Term
Interpret the results:
Urea slant: flesh color |
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Definition
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|
Term
Interpret the results:
Motility deep: diffuse growth from stab line |
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Definition
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Term
| What are two ways whereby microorganisms gain entry to the urinary tract? |
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Definition
Normal flora ascend to bladder
Bacteria filtered through kidneys descends to urethra |
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Term
| List 4 methods of obtaining urine specimens for culture, which is most common? |
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Definition
Clean, midstream voided specimen (most common)
Suprapubic aspiration
Cystoscopy
Aseptic catheterization |
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Term
| How many colony forming units per ml of urine are there if 150 colonies are counted on a plate innoculated with 0.001 ml of urine? |
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Definition
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Term
| Why is any bacterial count obtained from suprapubic aspiration significant? |
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Definition
| Because it is supposed to be contaminant free, should not have any colonies |
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Term
| If a urine specimen is left at room temperature for several hours before plating out the specimen, how might this affect the results? |
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Definition
| Organisms might keep multiplying, skewing the results |
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Term
| What ingredients make MacConkey agar selective for gram negative bacteria? |
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Definition
| crystal violet and bile salts inhibit growth of gram positive bacteria |
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Term
| What ingredients make macConkey agar differential for lactose fermentation? |
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Definition
| Lactose and pH indicator neutral red |
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Term
| Name a common causative agent of UTI that is gram negative and ferments the sugar lactose |
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Definition
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