Anti-biotics

Question 1

what is the physical control of microbial growth?

Answer 1

heat sterilisation, radiation sterilisation

Question 2

what is the chemical control of microbial growth?

Answer 2

antiseptics and disinfectants, natural antimicrobials and synthetic antimicrobials

Question 3

what are antiseptics

Answer 3

disinfecting agents with sufficiently low toxicity for host cells and can be used on skin

Question 4

what are sterilants

Answer 4

kill both vegetative cells and spores when applied to materials for appropriate times and temperatures

Question 5

what are the uses of antiseptics?

Answer 5

treatment of skin infections, prevention of infections in cuts and wounds, cleaning the skin area of surgery, prophylaxis and treatment of infections in mucosal areas, as a scrub for surgeons

Question 5

what are alcohols used as?

Answer 5

antiseptics and disinfectants to kill vegetative bacteria and fungi by denaturing proteins and disturb the membrane permeability

Question 6

what is chlorhexidine used as?

Answer 6

an antiseptic

Question 7

what types of bacteria is chlorhexidine most effective against?

Answer 7

gram+ cocci

Question 8

give an example of an oxidising agent

Answer 8

hydrogen peroxide

Question 9

what is the health warning with antiseptics, disinfectants and sterilant users?

Answer 9

they accumulate in the environment or in the patients/caregivers body

Question 10

what is the definition of an antibiotic?

Answer 10

a chemical substance produced by one organism that is destructive to another

Question 11

what are the two forms of antibiotics

Answer 11

bacteriostatic and bacteriocidal

Question 12

what are the cellular targets of antibiotics?

Answer 12

cell wall, cell membrane, nucleic acid, protein synthesis

Question 13

what are the properties of the ideal antimicrobial agent?

Answer 13

selective toxicity, cidal activity, long plasma half-life, good tissue distribution, low binding to plasma proteins, oral and parenteral preparations, no adverse drug interactions

Question 14

what are the antimicrobial targets?

Answer 14

inhibition of: cell wall synthesis, protein synthesis, nucleic acid replication and transcription, injury to plasma membrane, inhibition of synthesis of essential metabolites

Question 15

what molecules prevent cross linking of the cell wall?

Answer 15

beta-lactams e.g., penicillin

Question 16

how does penicillin inhibit the cell wall synthesis

Answer 16

it binds to penicillin binding proteins
inhibition of cross-linking of cell wall
accumulation of precursor cell wall units
cell lysis

Question 17

what molecules prevents vertical linking of the peptidoglycan?

Answer 17

glycopeptides e.g., vancomycin

Question 18

how does vancomycin work?

Answer 18

bind to terminal D-ala residues and prevents incorporation of sub-unit into growing peptidoglycan

Question 19

how do you inhibit the protein synthesis?

Answer 19

inhibit ribosomal subunits

Question 20

what are the resistance mechanisms of bacteria?

Answer 20

blocking entry, inactivating enzymes, alteration of target molecule, efflux of antibiotic

Question 21

give an example of how antibiotic resistance works with penicillin

Answer 21

the B-lactam ring in penicillin is broken by penicillinase

Question 22

what is the effect of antibiotic resistance on overall antibiotic effectiveness?

Answer 22

originally the effect of antibiotics decrease the number of bacteria by 4 logs but then it increases again so the net loss of bacteria is only 1 log