3 - Hospital acquired infection and antibiotic resistance

Question 1

What is an antibiotic?

Answer 1

an antimicrobial agent produced by a microorganism that kills or inhibits other microorganisms

Question 2

What is meant by ‘antimicrobial’?

Answer 2

chemical that selectively kills or inhibits microbes (bacteria, fungi, viruses)

Question 3

What is meant by ‘bactericidal’?

Answer 3

kills bacteria

Question 4

What is meant by ‘bacteriostatic’?

Answer 4

inhibits growth of bacteria (stops bacteria growing)

Question 5

What is meant by ‘antiseptic’?

Answer 5

chemical that kills or inhibits microbes to prevent infection

Question 6

What is ‘resistance’?

Answer 6

the ability of an organism to replicate in the presence go an antibiotic at a particular concentration

Question 7

What is MIC (minimal inhibitory concentration)

Answer 7

the lowest concentration of the antibiotic required to inhibit growth

Question 8

What is the name of the process of action of antibiotics?

Answer 8

SELECTIVE TOXICITY - they tend to inhibit processes that are unique to bacteria

Question 9

What is the mechanism of action of beta lactams?

Answer 9

interfere with the synthesis of peptidoglycan (bacterial cell walls)

Question 10

What type of antibiotic is tetracycline?

Answer 10

bacteriostatic (inhibits growth of bacteria)

Question 11

What is the mechanism of action of tetracycline?

Answer 11

inhibits protein synthesis
by binding to the 16S component of the 30S ribosomal subunit,
thus preventing charged aminoacyl tRNAs from binding to the mRNA/ribosome complex

Question 12

What type of antibiotic is chloramphenicol?

Answer 12

bacteriostatic

Question 13

What is the mechanism of action of chloramphenicol?

Answer 13

inhibits protein synthesis
by binding to the 50S subunit,
thereby blocking the peptidyl transfer step

Question 14

What type of antibiotic is quinolones?

Answer 14

bactericidal

Question 15

What type of antibiotic is sulphonamides?

Answer 15

bacteriostatic

Question 16

What type of antibiotics are aminoglycosides?

give some examples

Answer 16

bactericidal

e.g. gentamicin, streptomycin

Question 17

What type of antibiotics are macrolides?

give an example

Answer 17

only for gram positive infections

e.g. erythromycin

Question 18

What is responsible for the altered target site mechanism of AB resistance?

Answer 18

acquiring a gene that encodes a target modifying enzyme

(e.g.
MRSA has an acquired gene that produces an alternative penicillin binding protein, that performs the same function but has lower affinity to beta lactams)

Question 19

What is responsible for the inactivation of AB mechanism of AB resistance?

Answer 19

acquisition of a gene for an enzyme that breaks down the AB

Question 20

What is responsible for the altered metabolism mechanism of AB resistance?

Answer 20

• re-engineering the metabolic pathways so you bypass the shop that the AB affects
• increased production of an enzyme substrate to outcompete the AB inhibitor

Question 21

What is responsible for the decreased drug accumulation mechanism of AB resistance?

Answer 21

the drug doesn’t reach the sufficient concentration to be effective:

• reduced permeability of AB into the bacterial cell
• increase efflux of AB out of the cell

Question 22

What are the 3 sources of AB resistant genes?

Answer 22

plasmids
transposons
Naked DNA