Antibiotic Resistance

Question 1

What are the current major clinical problems?

Answer 1

MRSA

Carbapenem-resistant enterobacteriaceae (CRE)

Question 2

How often do infections occur after surgery?

Answer 2

3%

Question 3

What are some examples of CREs?

Answer 3

Escherichia coli
Klebsiella pneumoniae carbapenems
Salmonella

Question 4

Is CRE gram-positive or gram-negative?

Answer 4

Gram-negative

Question 5

What are the chances of dying with a CRE infection?

Answer 5

Approximately 50%

Question 6

What are the resistance mechanisms of bacteria?

Answer 6

Keeping antibiotics outside of the cell
Destroy or inactive antibiotic
Modify molecular target of antibiotic

Question 7

What is a difference between penicillin and vancomycin to gram-negative bacteria?

Answer 7

Penicillin can cross the outer membrane by the porin channels whereas vancomycin cannot

Question 8

What does a mutation in ompF lead to?

Answer 8

impermeable porins leading to resistance

Question 9

What is an example of a bacteria that has ompF and ompC?

Answer 9

E. coli

Question 10

What is intrinsic resistance?

Answer 10

innate ability of bacteria to resist antibiotic through its normal structure/function e.g. cell envelope, ribosome structure

Question 11

What is acquired resistance?

Answer 11

susceptible bacteria acquires resistance gene from another bacteria species/strain via HGT

Question 12

What is HGT?

Answer 12

Horizontal gene transfer

Question 13

What is an example of a bacteria with porin channels of low permeability?

Answer 13

Psuedomonas aeruginosa

Question 14

Ampicillin is used to treat E. coli , what spectrum drug is it?

Answer 14

Broad

Question 15

How do bacteria increase export of antibiotics?

Answer 15

Efflux pumps

Question 16

How does bacteria work against beta-lactam antibiotics?

Answer 16

Beta-lactamases which are hydrolytic enzymes that destroy/inactivate the antibiotic

Question 17

Where is Staphylococcus aureus found?

Answer 17

Nose
Skin folds
Hairline
Perineum
Navel

Question 18

What relatively minor infections are caused by Staphylococcus aureus?

Answer 18

Abscesses
Impetigo
Minor skin infections

Question 19

What more serious problems are caused by Staphylococcus aureus?

Answer 19

Cellulitis
Post-operative infection
Pueruperal fever
Catheter infections
Toxic shock syndrome

Question 20

What does MRSA stand for?

Answer 20

Meticillin resistant staphylococcus aureus

Question 21

What percentage of S. aureus bacteraemias are MRSA?

Answer 21

30%

Question 22

Why are there many HA-MRSA?

Answer 22

Puncturing of the skin

Catheters, IVs, surgery

Question 23

What is the difference between HA-MRSA and CA-MRSA?

Answer 23

HA-MRSA is more prevalent but CA-MRSA is more virulent

Question 24

How long did it take for S. aureus to become resistant to Meticillin?

Answer 24

1 year

Question 25

What allow S. aureus to be MR?

Answer 25

Chromosomal macA encodes altered PBP2’ (penicillin binding protein 2) - allows cell wall biosynthesis to continue

Question 26

What allows rapid spread of vancomycin resistant S. aureus?

Answer 26

VanR genes are mobile (transposons, plasmids)

Question 27

What are the new last resorts in treating MRSA?

Answer 27

Tigecycline

Linezoloid

Question 28

How is MRSA screened for?

Answer 28

Nose swab (or armpit/groin) -> sent to lab

Question 29

How to decolonise MRSA?

Answer 29

Nasal spray, body wash, shampoo with anti-MRSA
Prontoderm
Chlorhexidine glucognate
Mupirocin