#Enterococcus

Question 1

Most clinical Enterococcus infections are caused by ___ and ___

Answer 1

Most clinical infections produced by E. faecium and E. faecalis

Question 2

How do you identify Enterococcus based on morphology and enzyme testing (which 2 enzymes do you test and what are the results)?

Answer 2

gram-positive cocci in pairs and short chains

Catalase-negative

PYR (L-pyrrolidonyl arylamidase) positive

LAP (leucine aminopeptidase) positive

Question 3

What type of hemolysis does Enterococcus display?

Answer 3

Gamma i.e. no hemolysis

(eneterococcus Ein’t hemolytic)

Question 4

What are 4 virulence properties of Enterococcus?

Answer 4

Surface adhesion proteins: binds to host cells

Tissue damage by cytolysin and proteases (e.g., gelatinase, serine protease)

Gis proteins: general stress protein

Most important virulence property: antibiotic resistance

Question 5

Resistance to antibiotics in Enterococcus is mediated by___

Answer 5

Intrinsic resistance to cephalosporins, oxacillin

Acquired resistance to aminoglycosides, fluoroquinolones, vancomycin

Question 6

The antibiotic used to treat infection by E faecalis is ___. Which antibiotics would you use to treat E faecalis mediated endocarditis?

What is the antibiotic of choice for treating E faecium infection? Which drugs would you use to treat endocarditis?

Answer 6

E faecalis:

Ampicillin (or penicillin)

For endocarditis need two antibiotics: Ampicillin and an aminoglycoside

E faecium:

Vancomycin

For endocarditis need two antibiotics: Vancomycin and aminoglycosides

Question 7

What is the mechanism of resistance of vancomycin resistant Enterococcus?

Answer 7

Altering the terminal D-ala-D-ala to a D-ala-D-lac so antibiotics can’t bind there and aren’t effective

Question 8

VRE is an important cause of ___ infection

Answer 8

Nosocomial

Question 9

Clinical presentations of Enterococcus infection include endocarditis, __, __ and intra-abdominal and pelvic infection

Answer 9

Bacteremia

Endocarditis

Urinary tract infection

Intra-abdominal and pelvic infection

Question 10

For the following infections, determine whether you should treat for Enterococcus

Intra-abdominal and pelvic infections

Skin and soft tissue infections

Answer 10

Intra-abdominal and pelvic infections: generally not really unless culture is +ve for Enterococcus

Skin and soft tissue infections:

Since its a colonizer of the skin and soft tissue, DON’T TREAT unless it’s isolated from a deep/sterile culture, e.g. bone culture in diabetic foot infection

Question 11

Enterococcus is most likely a colonizer/contaminant in the following culture:

A.Cerebrospinal fluid culture

B.Blood culture

C.Urine culture

D.Superficial skin culture

Answer 11

D