Denise - Enterococci

Question 1

Write about enterococcus
(4)

Answer 1

Contains strains formerly in genus streptococcus

Currently 40 species recognised

Enterococcus faecalis
Enterococcus faecium

Question 2

What are the characteristics of enterococcus
(5)

Answer 2

Gram positive cocci

Often in pairs and chains

More ovate appearance than streps

Non fastidious

Capable of aerobic and anaerobic respiration

Question 3

What infections do enterococci cause
(5)

Answer 3

Often commensals

Urinary tract infection

Intra abdominal abscess

Endocarditis

Blood stream infection

Question 4

write about enterococci being commensals

Answer 4

Flora of the GIT
Most infections are endogenous
May be resistant to antimicrobials -> vancomycin-resistant enterococci (VRE)
Hospital acquired infection
Transmission and cross-infection

Question 5

What specimens is enterococcus seen in

Answer 5

Urine Samples UTI
Blood cultures BSI
Pus

Question 6

Write about surveillance for enterococcus

Answer 6

Enterococcus is often carriage
Screening in:
- rectal swab
- Screening for GI carriage especially VRE
- Carriage preceeds infection

Environmental Swab
- screening the hospital environment
- high touch surfaces

Question 7

Write about the laboratory isolation of enterococcus

Answer 7

Not fastidious
Non-haemolytic on blood agar
Magenta pinpoint colonies on MacConkey
Turquoise Blue on UTI Chromagar

Question 8

Write about enterococci on chromogenic VRE Medium

Answer 8

Brilliance Presumptive Differential Identification

Bluish green E. faecalis

Violet E. faecium

Question 9

What confirmatory tests are done on Day 2

Answer 9

Lancefield grouping
Growth on MacConkey
Temperature tolerant
Salt tolerant
Aesculin agar
Maldi Tof species ID confirmation
Molecular: resistance genes (Van A and Van B)

Question 10

Can Enterococci grow in bile

Answer 10

Yes grows on macConkey and bile aesculin agar

Question 11

How heat tolerant are enterococci

Answer 11

Grow at 45 degrees

Question 12

How salt tolerant are enterococci

Answer 12

Grow in 6.5% NaCl

Question 13

What are the basic characteristic tests of Enterococci

Answer 13

Gram positive cocci
KoH negative
Catalase negative
Oxidase negative

Question 14

Write about Vancomycin resistance

Answer 14

VRE
Responsible for 9% of all HAI

Question 15

What is the mechanism of vancomycin resistance

Answer 15

Alteration of cell wall precursors
8 acquired resistance phenotypes
Van A and Van B phenotypes most clincically significant

Question 16

What does Van A do

Answer 16

High level, inducible resistance to vancomycin and teicoplanin

Question 17

What does Van B do

Answer 17

Moderate to high level resistance to vancomycin but susceptible to teicoplanin

Question 18

How are enterococci treated

Answer 18

Ampicillin
Gentamicin
Vancomycin
Quinupristin + dalfopristin
Linezolid

Question 19

Write about enterococci resistance
(3)

Answer 19

Many isolates show resistance to combination therapy with B-lactam plus an aminoglycoside

Many isolates show resistance to vancomycin

Used to treat infection with vancomycin- resistant infections with E. faecium