Review 3: S.aureus Flashcards
1. Know the following characteristics about each disease studied: Genus and species name Gram reaction Cell shape Disease name Transmission Virulence factors Clinical symptoms of disease Treatment
Genus and species name: Staphylococcus aureus Gram reaction: Gram + Cell shape: coccus Disease name: Transmission: Virulence factors: Clinical symptoms of disease: Treatment:
- Be able to translate the organism’s genus and species name into the English language.
As you know, “staphylococcus” means “cluster of round, ball-shaped bacteria.”
“Aureus” is derived from “aurum,” which is Latin for “gold.” (That’s why Gold is “Au” on the Periodic Table)
- Define pyogenic.
Pyogenic (pus generating) cocci
- Define Beta-hemolytic
Beta-hemolytic: complete destruction of red blood cells
- What is the preferred site of colonization in the human body by S.aureus?
Nose is preferred site for S.aureus or moist skin
- Outline the 6 virulence factors for S.aureus and explain them.
- Hemolysins
- Protein A:
- Hyaluronidase
- Leukocidin
- Coagulase
- Capsule:
- Which virulence factors are structural parts of S.aureus bacteria cell? (Hint: there are 2)
Protein A
Capsule
- Which virulence factors are secretions by S.aureus bacteria cell? (Hint: there are 5)
- Hemolysins
- Protein A:
- Hyaluronidase
- Leukocidin
- Coagulase
- What are the differences between an exogenous, endogenous, nosocomial and opportunistic infection with S.aureus?
**not fully answered***
exogenous
endogenous: Endogenous Source
due to patients own Staph strain
Impaired host resistance (poor health, chemotherapy)
Skin wound(animal bite, burn)
nosocomial: hospital acquired (extensive surgery, aseptic procedures not enforced)
opportunistic infection: Endogenous Source
due to patients own Staph strain
Impaired host resistance (poor health, chemotherapy)
Skin wound(animal bite, burn)
- What is the single most important thing that nurses and doctors can do in a clinical setting to deter transmission of nosocomial infections between patients?
Wash their hands.
- What is the CDC?
Center for Disease Control
- What are the specific differences between Folliculitis, Furuncle and Carbuncles as they relate to a Staph infection? Which one of these is most serious?
Folliculitis:
Inflammation of a hair follicle
Small red bump, pimple
Pus in the hair follicle
Causes: shaving, blockage of follicle (dirt), friction from clothing (jeans)
Damaged follicle can then be infected by Staph
Furuncle:
Round, red painful, pus-filled sore on the skin
Exterior abscess
Infected hair follicle that extends to adjacent subcutaneous tissue
Pus may drain from boil
Carbuncles:(cluster of boils)
Massive lesion, further spread of abscess
Large area of redness, swelling, pain, and several sites of draining pus
Fever present
Most serious is Carbuncles
- Define Abscess.
Pus filled: living and dead WBC, dead tissue, infectious agent
No blood vessels: destroyed or pushed aside
Helps to localize infection most oral antibiotics noneffective (absence of blood flow)
- Is an abscess treatable with only oral antibiotics? Why or why not?
No. Because a walling off abscess by inflammation may prevent antibiotics from reaching abscess in effective quantities which is one reason drainage of abscess is so important.
- Adequate drainage of abscess (lance)
- Debridement: surgical removal of necrotic tissue (dead)
- Antibiotic Therapy
- What is septicimea?
Abscesses can expand (or rupture) into the bloodstream and cause septicemia
Septic = diseased, -emia = blood
Remember, pus is poisonous garbage! You don’t want your abscess draining into your bloodstream, any more than your septic tank!
Septicemia can cause:
A massive, life-threatening, systemic infection!
Abscesses to form in the heart, bone, and joints!
Septicemia is pretty much the Worst Case Scenario of the average Staph infection
- What are the different levels of a wound infection?
Superficial: skin and subcutaneous (easiest to treat)
Deep: muscle or bone
Organ Space: involves an organ infection usually from surgical wounds (most serious)
- Is drug resistance a problem in treating S.aureus infections?
Yes!!!
- Define MRSA.
MRSA (methicillin resistant Staphylococcus aureus)
- Is MRSA treatable?
Yes but it is becoming harded to do so due to its ability to mutate.
- What is a phage (as discussed on the MRSA film)?
Virus that infects Staph infection
- Why is phage typing a useful laboratory tool in identifying different strains of Staph bacteria in a clinical setting?
Allows infection control team to compare MRSA bacteria strains and determine how many patients are infected with those strain
- Does the human body mount an effective immune response against S.aureus?
No
- What category of patient is at most risk of Staph infections?
ill patients / wound/surgery
- Outline the 6 virulence factors for S.aureus and explain them.
- Hemolysins
Hemolysins:
a) hemo: hemoglobin b) lysin: lyse c) destroy red blood cells d) β(beta) – hemolytic
- Outline the 6 virulence factors for S.aureus and explain them.
- Protein A:
Protein A:
a) found in cell wall and as a secretion by bacteria b) resists phagocytosis c) binds to IgG so Ab cannot bind to MØ
- Outline the 6 virulence factors for S.aureus and explain them.
- Hyaluronidase
Hyaluronidase –
a) breaks down hyaluronic acid, b) promotes tissue penetration, c) produced by 90% of S.aureus strains
- Outline the 6 virulence factors for S.aureus and explain them.
- Leukocidin
Leukocidin
Leuko – leukocytes
cidin – means to kill or destroy
kills neutrophils
interferes with non-specific resistant mechanisms- Outline the 6 virulence factors for S.aureus and explain them.
- Coagulase
Coagulase –
a) causes plasma to clot
b) promotes attachment to host tissue
c) actually helps wall off infection in an abscess
d) hinders movement of WBC to infection by producing clots in capillaries
- Outline the 6 virulence factors for S.aureus and explain them.
- Capsule
Capsule:
a) polysaccharide b) inhibits phagocytosis
