REMAKE

• Where is staph. Aureus commonly found?

  Nose
• What types of infection does staph. aureus cause?

  pneumonia, endocarditis, osteomyelitis,
• What are MRSA and VRSA?

  MRSA: Methicillin-resistant Staphylococcus aureus VRSA: Vancomycin-resistant Staphylococcus aureus
• What is a enriched media?

  Media containing additional nutrients or growth factors to support the growth of fastidious organisms.
• What is a selective media?


  Media that allows the growth of certain types of microorganisms while inhibiting the growth of others.
• What is differential media?

  Media that allows for the differentiation of different types of microorganisms based on their growth characteristics.
• Is mannitol salt agar selective or differential?

  selective: salt is selective for staph species

  differential: mannitol fermenters turn plate from red to yellow in order to differentiate staph species
• Interpret the results for the following plate

  Both grew meaning that both are species of staph.

  -Left: mannitol fermenter

  -Right: does not ferment mannitol

  
• What is the name of this test and purpose?

  Blood Agar plate

  -To see if the bacteria are able to produce the exotoxin hemolysin which allows them to destroy erythrocytes present in the agar

  
• Interpret the following plate

  Left: beta-hemolysis meaning that it was able to destroy all erythrocytes

  Middle: alpha-hemolysis meaning that the erythrocytes were partially broken down

  right: gamma hemolysis meaning that the bacteria were not able to produce hemolysin and could therefore not destroy erythrocytes

  
• Is this plate enriched, differential, or selective?

  Enriched: contains blood allowing for certain organisms to grow

  differential: hemolysis patterns will help us differentiate organisms

  
• Why do we streak and stab a blood agar plate?

  Some hemolytic activity can differ depending on the amount of oxygen available therefore, we streak to create aerobic condition and stab for anaerobic condition
• What is the name of this test and what is its purpose?

  Coagulase test

  -Testing to see if organism can produce the enzyme coagulase which helps it use the fibrin in our blood plasma to create a protective barrier around itself

  
• How does coagulase benefit an organism?

  -resists phagocytosis

  -resist immune responses

  -resist anti microbial agents

  -forms protective barrier
• what types of organisms do we perform a coagulase test on?

  Gram +

  catalase +

  -usually to identify staph. aureus which is positive
• What is the name of this test and purpose?

  The Novobiocin resistance test

  -Purpose is to see if an organism is resistant or susceptible to the antibiotic novobiocin

  
• Interpret the results of the following plate

  Left: resistant, the zone of inhibition is so small meaning that the antibiotic was not able to affect the bacteria that much

  right: susceptible, the zone of inhibition is very large therefore novobiocin is an effective antibiotic to use against this organism

  
• What are the three genera often implicated in gram + cocci?

  staphylococcus

  streptococcus

  enterococcus
• How is staph aureus distinguished from other staphylococcus species?

  Coagulase-positive
• Who discovered penicillin?


  Alexander Fleming
• what is an antimicrobial drug?


  interferes with the growth of microbes within a host
• what is an antibiotic?


  a substance produced by a microbe that in small amounts, inhibits another microbe
• What leads to antibiotic resistance?

  -misuse

  -using expired antibiotics

  -not it finishing your prescription

  -using antibiotics for inappropriate conditions

  -using antibiotic in animal feed

  -mutations
• What are the mechanisms of antibiotic resistance?

  -enzymatic destruction of drug

  -prevent penetration

  -alteration of drug’s target site

  -rapid ejection of drug
• How are resistance genes acquired?

  plasmids, transposon, horizontal gene transfer
• What is the name of this test and its purpose?

  6.5% NaCl broth

  -To differentiate Group D from Enterococci

  -enterococcus is positive group D is negative

  
• What is the name of this test and what is its purpose?

  PYR test

  -To differentiate streptococcus pyogenes from other strep and enterococcus species based on the production of enzyme PYRase

  
• What is the name of the following test? What kind of media is used to perform it and what is its purpose?

  CAMP test

  -blood agar plate

  -To identify group B streptococcus species based on if a synergistic enhanced zone of hemolysis is created between staph. aureus and the unknown organism

  
• How are streptococcus divided?

  into groups by antibodies that recognize surface antigens

  -A,B, and D
• What diseases does strep pyogenes cause?

  Strep throat, scarlet fever, rheumatic fever, and necrotizing fasciitis.
• What types of diseases does strep agalactiae cause?

  Neonatal sepsis, pneumonia, meningitis, postpartum infections
• What does strep. mutants cause?

  Dental cavities, pharyngitis, endocarditis
• What does E. faecalis cause?

  UTIS, infection of prostate, intra-abdominal infection
• What does strep. Bovis cause?

  Endocarditis, chronic liver disease, sepsis
• Interpret the results of the following test

  Left: negative does not produce PYRase

  Right: positive for enzyme PYRase

  
• Interpret the results of the following tubes

  Left: positive for salt tolerance

  right: negative

  
• Is the bile esculin selective, differential, or enriched media?

  selective: selects for enterococci and some strep. via bile

  differential: dark precipitate indicates that esculin was hydrolyzed into esculetin
• Which test do we not perform on staphylococcus?

  PYR test
• What is the Kirby Bauer Test?


  Antibiotic susceptibility test in which we create a lawn of bacteria in order to test if an organism is susceptible or resistant to different antibiotics
• what are enterobacteriaceae?


  Family of bacteria