Antimicrobial therapies

Question 1

describe 3 properties of aminoglycosides

Answer 1

.Bactericidal
.target protein synthesis, RNA proofreading ,damages cell membrane
Toxic

Question 2

name two aminoglycosides

Answer 2

• Gentamicin, streptomycin

Question 3

Give 4 features of rifampicin

Answer 3

•Bacteriocidal
Targets RpoB subunit of RNA polymerase
.Spontaneous resistance is frequent
. makes secretions orange/red

Question 4

I target lipid II component of cell wall biosynthesis as well as wall cross linking via D-ala residues, i am bactericidal, i am toxic, what antibiotic am i?

Answer 4

Vancomycin

Question 5

give me 3 features of vancomycin

Answer 5

.Bactericidal
. TARGET lipid II components of cell wall biosynthesis as well as wall crosslinking via d-ala residues
.toxic

Question 6

I inhibit the initiation of protein synthesis by binding to 50S rRNA subunit, i am bacteriostatic, i exhibit gram positive spectrum activity, i am…

Answer 6

linezolid

Question 7

give 3 features of linezolid

Answer 7

.BACTERIOSTATIC
. inhibits initiation of protein synthesis by binding to 50S rRNA subunit
Gram-positive spectrum of activity

Question 8

I am bactericidal, target cell membrane, gram positive bacteria are affected, toxic, what i am i?

Answer 8

Daptomycin

Question 9

GIVE 4 features of daptomycin

Answer 9

.Bactericidal
.Gram positive bacteria
.Targets cell membrane
.toxic

Question 10

i inhibit synthesis of petidioglycan by binding to Penicillin-binding proteins (PBP). E.g i am Penicillin and methicillin. What kind of antibiotic am i?

Answer 10

BETA LACTAMS

Question 11

Give 2 examples of beta lactams

Answer 11

penicillin and methicillin

Question 12

what do beta lactams do?

Answer 12

interfere with synthesis of petidoglycan component of cell wall by binding to Penicillin-binding proteins (PBP)

Question 13

give 2 examples of macroslides

Answer 13

erythromycin, azithromycin

Question 14

describe macrolides

Answer 14

.gram positive+ gram negative

. Targets 50s ribosomal subunit preventing amino-acyl transfer hence truncates polypetides

Question 15

I am synthetic, broad spectrum, bactericidal.
I target DNA gyrase and topoisomerase IV in both gram + and - bacteria
what am i?

Answer 15

quinolones

Question 16

Explain the function of quinolones

Answer 16

.synthetic, bacteriocidal, broad spectrum

. TARGET DNA gyrase and topisomerase IV in + and - bacteria

Question 17

describe the interaction of DNA gyrase and quinolone

Answer 17

QUINOLONE stabalises the DNA-DNA gyrase complex hence broken strands cant be released and DNA REPLICATION IS BLOCKED

Question 18

what are the 4 machanisms that cause antibiotic resistance

Answer 18

. altered target site
.altered metabolism
. inactivation of antibiotic
.decreased drug accumulation

Question 19

how can an altered target site arrise?

Answer 19

via acquistion of alternative gene or gene that encodes a target-modifying enzyme

Question 20

streptococcus pneumoniae resistance to erythromycin occurs how?

Answer 20

via acquisition of erm genes which encodes an enzyme that methylates the AB target site in the 50S ribosomal subunit

Question 21

Methicillin-resistant Straphylococcus aureus (MRSA) encodes…

Answer 21

an alternative PBP with low affinity to beta lactams

Question 22

2 examples of enyzmes which degrade antibiotics

Answer 22

beta-lactamse and cat ( chloramphenicol acetyl transferase)

Question 23

give 2 broad spectrum beta lactamases

Answer 23

ESBL, NDM-1

Question 24

explain altered metabolism in antibiotic resistance

Answer 24

. Increased production of enzyme substrate can out compete antibiotic inhibitor (e.g increased PABA allows resistance to sulfonamides)
.Bacteria switch to other metabolic pathways reducing need for PABA.

Question 25

3 sources of antbiotic resistant genes

Answer 25

plasmids transposons naked DNA

Question 26

explain the three sources of antibiotic resistant genes

Answer 26

PLASMIDS-extra chromosomal circular DNA, carries multiple AB resistant genes TRANSPOSONS- integrate into chromosomal DNA, allow transfer of genes from plasmids to chromosome and vice versa .Naked DNA- DNA from dead bacteria released into environment

Question 27

WHAT ARE THE 5 NON GENETIC MECHANISMS OF RESISTANCE TO ANTIBIOTICS

Answer 27

``` .Biofilm .intracellular location .slow growth .spores .Persisters ```

Question 28

Reasons antibiotic treatment fail are..

Answer 28

``` . Inappropiate choice for organism Poor penetration of ab into target site .INAPPROPIATE dose wrong administration e.g oral v.s IV) PRESENCE OF AB within commensal flora e.g secretion of beta-lactamase ```

Question 29

what 3 misconceptions were made at dawn of antibiotic era

Answer 29

.RESISTANCE WOULD NOT HAPPENS TO MORE THEN ONE CLASS OF ANTIBIOTICS AT THE SAME TIME . Horizontal gene transfer would not occur RESISTANT ORGANISMS WOULD BE LESS ‘FIT’.

Question 30

5 RISK FACTORS OF HOSPITAL AQQUIRED INFECTIONS

Answer 30

``` .crowded wards immunosupression broken skin e.g surgical wound/IV catheter AB therapy may supress normal flora transmission by staff ```

Question 31

How can antibiotic resistance be overcome?

Answer 31

modify meds e.g prevent cleavage of beta lactams or enhance efficacy e.g METHICILLIN combinations of antibiotic+inhibitor e.g Beta lactamase+Augmentin