Controlling Microbes

Question 1

sterilization

Answer 1

no living cells, spores, or viruses

Question 2

disinfectant/disinfection

Answer 2

killing, inhibiting, removing organisms that cause disease from inanimate objects

Question 3

sanitization

Answer 3

reducing microbial numbers to levels safe for the public

Question 4

antiseptics

Answer 4

kill or inhibit infection-causing organisms from living tissue

Question 5

germicides

Answer 5

kill certain organisms (ex: fungicide, bactericide, etc.)

Question 6

factors affecting anti-microbial efficiency

Answer 6

• population size
• population composition
• concentration of anti-microbial agent
• length of exposure
• temperature
• local environment (other drugs can change antibiotic efficiency)

Question 7

selective toxicity

Answer 7

what does the pathogen have that the host doesn’t?

Question 8

what are the 5 modes of killing of antibiotics?

Answer 8

1. bind to ribosomes, stop translation
2. stop cell wall synthesis (penicillin!!)
3. disrupt membranes
4. stup nucleic acid synthesis
5. inhibit metabolic pathways

Question 9

list 5 bacterial mechanisms of antibiotic resistance

Answer 9

1. target modification: changes to RNA sequence in the ribosomes or alterations in tetrapeptide amino acids in ppg, so the antibiotic can no longer recognize/bind bacteria
2. drug-altering enzymes: alters antibiotic so it no longer works
3. drug-degrading enzymes: degrade antibiotic
4. prevent drug entrance (efflux pumps and innate resistance)
5. alternative pathway: bacteria can use a different metabolic pathway, bypassing the one targeted by the drug

Question 10

describe the two ways bacteria can prevent drug entrance

Answer 10

1. efflux pumps: plasma membrane translocases that are nonspecific, meaning multiple antibiotics can get in, and they all get yeeted back out
2. innate resistance: for example, many gram-negatives are just unaffected by penicillin G

Question 11

describe how antibiotic resistance comes about

Answer 11

resistant mutants arise spontaneously and are then selected for in the presence of antibiotics, but the drugs do not influence the mutations! (antibiotic resistance can be due to plasmids or mutations)

Question 12

what are the two ways bacteria acquire drug resistance?

Answer 12

1. receive resistance genes from other bacteria
2. spontaneous, random mutations

Question 13

why is it difficult to achieve selective toxicity with anti-fungals and anti-protozoals?

Answer 13

fungi and protozoa are eukaryotes like our cells are, so it is hard to target something in them that wouldn’t be harmful to us

Question 14

discuss anti-virals

Answer 14

difficult o achieve selective toxicity because viruses get inside our own cells