Antibiotic resistance AB

Question 1

What are the three classifications of antibiotic resistance, when described by mechanism?

Answer 1

Antibiotic inactivation
Alteration of target
Decreased uptake

Question 2

What is an example of antibiotic inactivation?

Answer 2

Betalactamases

Pneumococcus and macrolides (erm)

Enzymatic modification of aminoglycosides

Question 3

What is an example of alteration of antibiotic target?

Answer 3

Pneumococcus and penicillin

S aureus and methicillin-like antibiotics

Question 4

What are two mechanisms of decreased uptake?

Answer 4

Reduced penetration

Antibiotic efflux

Question 5

What is an example of intrinsic antibiotic resistance (i.e. the resistance has always been there) ?

Answer 5

E coli and penicillin or vancomycin

Klebsiella and amoxycillin

Question 6

What is an example of acquired antibiotic resistance?

Answer 6

S aureus and penicillin

Pseudomonas and ciprofloxacin

Question 7

Broadly speaking, what are the two genetic mechanisms of developing resistance?

Answer 7

Spontaneous DNA mutations (SNPs)

Acquisition of new DNA

Question 8

Give an example of spontaneous DNA mutations in genetic mechanisms of resistance?

Answer 8

M tuberculosis

S aureus and Rifampicin

Question 9

What are the modes of acquisition of new DNA in genetic mechanisms of resistance?

Answer 9

TRANSFORMATION - part of the bacterial chromosome integrated into another bacterial chromosome

CONJUGATION - mobile plasmid enters a different bacterium

TRANSDUCTION - bacteriophage

Question 10

What is the gene involved in resistance of MRSA?

Answer 10

mecA gene

Question 11

What is the main mechanism of resistance in MRSA?

Answer 11

Acquisition of altered penicillin binding protein

Question 12

What are the two genes involved in the resistance of VRE?

Answer 12

VanA

VanB (Australia)

Question 13

What is the mechanism in the resistance of VRE?

Answer 13

Encode for altered pentapeptide peptidoglycan precursor - decreased affinity

Question 14

What is the treatment for VRE?

Answer 14

Linezolid
Tigecycline
Daptomycin

Question 15

What is the mechanism of penicillin-non-susceptible S pneumoniae?

Answer 15

Altered penicillin-binding-protein (not beta-lactamase)

Question 16

What are the four classes of beta-lactamase enzyme classes

Answer 16

A - Penicillinases
B - Metalloenzymes
C - Cephalosporinases
D - Oxacillinases

Question 17

What are the genes in penicillinase (A) resistance?

Answer 17

TEM
SHV (Klebsiella)
CTX-M

Question 18

What are the genes in the metalloenzyme (B) group?

Answer 18

NDM
VIM
IMP

Question 19

What is an example of inducible beta lactamase activity?

Answer 19

Class C (Cephalosporinases) - AmpC-type

ESCAPPM

Question 20

What are the ESCAPPM organisms?

Answer 20

Enterobacter
Serratia
Citrobacter
Acinetobacter
Proteus (not mirebalis)
Providentia
Morganella

Question 21

What is the mechanism of resistance in ESBL?

Answer 21

Mutations in existing beta-lactamase genes (e.g. TEM, SHV)

Plasmid mediated transfer

Question 22

What is the treatment of ESBL?

Answer 22

Carbapenem
Colistin
Amikacin

Question 23

What are two examples of class B metallo-beta-lactimases?

Answer 23

Pseudomonas

Acinetobacter

Question 24

What is the mechanism of resistance in metallo-beta-lactamases

Answer 24

Plasmid mediated transfer (usually)

Question 25

What is the mechanism of aminoglycoside resistance?

Answer 25

Decreased permeability

Question 26

What is the mechanism of resistance in VISA?

Answer 26

Thickened cell wall (D-ala-D-ala)

Question 27

When is VISA commonly seen?

Answer 27

Mainly in dialysis patients or those with infected foreign bodies

Question 28

What do Van A and B genes code for?

Answer 28

D-ala-D-ala

Question 29

Which antibiotic should be be avoided with concurrent SSRI or Tramadol use?

Answer 29

Linezolid

Question 30

What are the anti-pseudomonal antibiotics?

Answer 30

``` Tazocin Ceftazadime Cefepime Meropenem (not ertapenem) Tobramycin Gentamicin Ciprofloxacin Aztreonam Colistin ```

Question 31

Which antibiotics treat VRE?

Answer 31

Linezolid Daptomycin Tigecycline

Question 32

Which antibiotics treat VISA?

Answer 32

Linezolid

Question 33

In what setting should Fosfomycin be used?

Answer 33

PO agent Mainly used for resistant UTIs (not pseudomonas)

Question 34

What does Colistin work well against?

Answer 34

Pseudomonas Acinetobacter E coli Some Enterobacter, Klebsiella, Salmonella and Stenotrophomonas NOT other ESCAPPM

Question 35

Which organisms are resistant to Meropenem?

Answer 35

``` Legionella pneumophila Enterococcus FAECIUM Stenotrophomonas Coxiella burnetti MRSA Candida albicans M pneumoniae ```