MLT 207 Review
List the steps in gram staining.
Crystal Violet
Iodine
Decolorizer (Alcohol)
Safranin
This is the major pathogen of the Staphylococcus family.
What is S. aureus?
Give the BAP description if you were to isolate Staph aureus.
Yellow/tan/white colored colony, buttery, Beta-hemolytic.
Arguably the most important test in differentiating Staph vs Strep.
What is the catalase test?
This is the main reagent in the catalase test.
What is hydrogen peroxide?
Blood Agar is considered this type of media...
What is Differential Media?
This is the best way to differentiate Staphylococcus from Micrococcus...
The (modified) oxidase test
This is the most critical distinction between S. aureus and other staphylococci.
Production of coagulase
Which Lancefield group does Strep agalactiae belong?
Group B
This is the primary Streptolysin found in Strep. pyogenes.
What is Streptolysin O?
Instruments such as the Vitek or Microscan identify organisms based the organism's what?
Biochemical Reactions
These are the two organisms the Novobiocin disk will help differentiate between.
S. epidermidis and S. saprophyticus
This strep is often presents as a UTI in sexually active young women and is typically Novobiocin resistant.
What is S. saprophyticus?
The optochin (P) disc helps to identify this organism.
What is S. pneumoniae
An organism is growing on the Blood plate. Upon gram staining, it is found to be gram positive cocci in chains. It is also catalase-negative, Beta-hemolytic, and bacitracin-sensitive. What is the most likely organism?
S. pyogenes
Give a description of the following terms:
Beta-hemolytic
Alpha-hemolytic
Gamma-hemolytic
Beta: complete zone of clearance
Alpha: small zone of clearance, usually a greenish color
Gamma: no clearance whatsoever
This specific organism is resistant to Beta-lactam drugs, often making it hard to treat.
What is MRSA?
Toxic Shock Syndrome and Impetigo are associated with these two organisms.
What is S. aureus and S. pyogenes?
These are the most common infections associated with S. agalactiae.
Neonatal pneumonia, meningitis, and bacteremia
Formally known as Group D strep, this organism is known to cause UTIs and wound infections. Often presents as a grayish, alpha to gamma hemolytic colony on the blood agar plate.
What is Enterococcus?
Give a short definition of the following terms:
Aerobic
Obligate Aerobe
Mesophilic
Obligate Anaerobe
Aerobic- grow best in the presents of oxygen
Obligate Aerobe- require oxygen to grow
Mesophilic- grow best in 30-45 degrees C (body temp)
Obligate Anaerobe-require growth in oxygen poor environment
A catalase positive, gram-positive cocci is isolated. You put a loop of organism on a glass slide and add rabbit plasma. Clumping is observed. You should suspect this organism.
What is S. aureus?
This organism is most often found as normal flora on the skin, mouth, GI tract, and other areas of the body.
What is S. epidermidis?
A gram positive cocci is isolated from a blood culture has the following test results:
optochin: negative
bacitracin: negative
bile esculin: negative
hippurate hydrolysis: positive
catalase: negative
What is the most likely organism?
S. agalactiae
Which organism can be used as a positive quality control for the bile esculin test?
What is E. faecalis?