Question Answer
Define opportunists. Orgs that normally do not cause disease unless the conditions become favorable.
Term used to describe a preliminary report sent to a physician before all testing has been completed. Presumptive report
What is catalase? An enzyme produced by ALL Staphylococcus spp.
Where can Staph epidermidis be found as a natual inhabitant of the body? S. epidermidis is a natural inhabitant of the skin and mucous membranes
Term given to Staphylococcus organisms that do not have the capability to produce the coagulase enzyme. Coagulase Negative Staph (CNS)
Which CNS is the most frequently grown in the microbiology department? Staph epidermidis
What do colonies of Staph saprophyticus look like on a BAP plate? S. saprophyticus cannot be distinguished from other CNS on a BAP plate
Define pathogen. Organism capable of causing disease.
What gram stain morphology does Staph aureus have? gram positive cocci in clusters
What three factors do Staph aureus organisms possess that contribute to their virulence? 1. structural components of the cell wall, 2. enzymes, and 3. toxins
True or False: Staph saprophyticus is not a CNS. False–Staph saprophyticus IS a CNS.
What simple laboratory test can distinguish Staph aureus from the CNS? The coaulase test.
What is novobiocin? An antibiotic
Which of the following organisms would most likely present with the following characteristics: gpc, catalase (+), coagulase (-), novobiocin resistant?

Staph aureus, Staph epidermidis, or Staph saprophyticus

Staph saprophyticus WHY: S. sapro is the only Staph spp resistant to novobiocin
Staph species which is resistant to the antibiotic novobiocin. Staph saprophyticus
What is trhe gram stain reaction and morphology of the Micrococcus spp? gpc in pairs, tetrads, clusters and/or chains
What gram stain morphology do Micrococcus species have? gram positive cocci in tetrads
Staph saprophyticus can be found to inhabit what part of the human body? the GU (genitourinary) tract of humans
What Staph species is considered the second most common cause of UTIs (urinary tract infections) in women? Staph saprophyticus
What is beta hemolysis when seen on a BAP plate? Complete hemolysis of the RBCs in the BAP media.
A wound culture grows out a gpc with the following characteristics: Beta-hemolytic colonies on a BAP that are both catalase (+) and coagulase (+). What is the MOST likely organism? Staph aureus
Staph epidermidis is associated with all of the following except:

wound infections, bacteremias, nosocomial urinary tract infections, or toxic shock syndrome

toxic shock syndrome–S. aureus is associated with this type of infection
Define saprophytic. Saprophytic means surviving on decaying matter
All of the following may be used to identify Staph epidermidis except:

catalase reaction, coagulase reaction, gram stain morphology, B-lactamase reaction

B-lactamase reaction. WHY: S. epi cannot produce the enzyme B-lactamase.
What enzyme produced by certain strains of Staph aureus can cleave (breakdown) the structure of penicillin and render it useless as an effective antiobiotic? The beta-lactamase enyzyme
Describe what Staph epidermidis organisms look like on a BAP plate. Colonies are small/medium, non-hemolytic, smooth/round, and white
What is coagulase? An enzyme that can clot or coagulate plasma.
True or False: Staph saprophyticus is a CNS. True
In what areas of the body do Staph organisms normally inhabit? Normally Staph spp. inhabit the skin and mucous membranes
Where can Micrococci spp. be found as inhabitants? Skin and environment
Describe what colonies of Staph aureus look like on a BAP plate. medium/large, smooth, round, white to creamy colored colonies. beta hemolytic
Name three infections caused by toxins produced by Staph aurues organisms. 1. Toxic Shock Syndrome, 2. Scalded Skin Syndrome, and 3. Food poisoning
Staphylococcal food poisoning is characterized by:
A.rapid onset–within 2-6 hours of ingestion of enterotoxin, B.colonization of the GI tract by the bacterium,C. a 2day-2 week incubation period,D. diarrhea, but no vomiting
C. a 2 day – 2 week incubtion period
Define pyogenic. pus producing
What do colonies of Micrococci spp. look like on a BAP plate? Often pigmented, ranging in color from beige to bright yellow or orange.
Term used to describe a final report sent to a physician when all necessary testing has been completed. Definitive report
A positive blood culture shows gram positive cocci in tetrads. The following day, yellow pigmented colonies are observed on a BAP plate. The colonies test catalase (+). What is the MOST likely organism? Micrococcus spp.

Previous Article

Leave a Reply

Your email address will not be published. Required fields are marked *