Microbiology: antibiotics

Question 1

what does bactericidal and bacteriostatic mean

Answer 1

cidal = kills bacteria
static = inhibit bacterial growth

Question 2

describe the 3 ways antibiotics can work by

Answer 2

act on bacterial cell wall- interfere with peptidoglycan synthesis
affect bacterial ribosome, interfere with protein synthesis
act on bacterial DNA- interfere with nucleic acid synthesis

Question 3

what types of antibiotic work by acting on the cell wall and are they bacteriacidal or static

Answer 3

penicillins, cephalosporins, glycopeptides

they are all bacteriacidal

Question 4

what types of antibiotic work by affecting protein synthesis(bacterial ribosomes), are they bacteriacidal or static

Answer 4

macrolides(static), tetracyclines(static), aminoglycosides(cidal)

Question 5

what antibiotics work by acting on bacterial DNA

Answer 5

metronidazole, trimethoprim, fluroquinolones

Question 6

give function, some properties of penicillins and an example

Answer 6

stops cross linking + causes autolysins to degrade cell wall
excreted rapidly via kidneys, safe in pregnancy
example = flucloxacillin

Question 7

describe how glycopeptides work and give an example

Answer 7

bind to end of growing chain during synthesis to prevent cross linking + weaken wall
example = vancomycin

Question 8

give an example of a macrolide and a tetracyclin

Answer 8

macrolide = erythromycin
tetracyclin = doxycycline

Question 9

give a property of aminoglycosides and an example

Answer 9

mainly active against gram negative organisms

example = gentamicin

Question 10

what is the 1st line antibiotic used in treatment of coliforms( gram -ve)

Answer 10

Gentamicin

Question 11

describe how fluroquinolones work

Answer 11

stop supercoiling of bacterial DNA so it cannot replicate

Question 12

what are the 4 Cs to avoid using and why

Answer 12

cephalosporins, co-amoxiclav, ciprofloxacin, clindamycin

to avoid increased risk of C. diff

Question 13

what are the 4 ways bacteria are becoming resistant to antibiotics

Answer 13

genetic mutation, transformation, conjugation, transduction

Question 14

briefly describe the transfer of genetic code from bacteria to another in terms of antibiotic resistance
(transformation, conjugation, transduction)

Answer 14

transformation = DNA that codes for resistance scavenged from DEAD bacteria
conjugation = 2 bacteria CLOSE TOGETHER form bridge and pass across info. to code resistance
transduction = VIRUSES infecting bacteria can transfer DNA from one bacteria to another