Antimicrobial resistance and resistance transfer

Question 1

what are the 5 major targets of antibiotics?

Answer 1

1. cell wall synthesis
2. protein synthesis.
3. nucleic acid synthesis.
4. metabolic pathways.
5. cell membrane fucntion

Question 2

what are mobile genetic elements of pathogens?

Answer 2

plasmids
transposons
integrons

Question 3

what is a plasmid?

Answer 3

a DNA molecule that exists seperate to the host chromosome.

Question 4

what is the structure of a plasmid?

Answer 4

circular, self-replicating and double stranded DNA

Question 5

what happens to plasmids when bacterial cells divide?

Answer 5

the plasmids are also replicated.

Question 6

example of a resistant plasmid?

Answer 6

R100 - multiple resistance, self-transmissable.

Question 7

Mechanisms of antibiotic resistance?

Answer 7

ANSWER

Question 8

what are the main ways antibiotic resistance can be spread between bacteria?

Answer 8

• conjugation
• transformation
• transduction

Question 9

what is conjugation?

Answer 9

?

Question 10

what is transformation?

Answer 10

the bacteria may take up genes (such as resistant genes from dying bacteria), integrating it into the genome/plasmid, making it resistant

Question 11

what is transduction?

Answer 11

bacteriophage (virus) can spread antibiotic resistance by packaging a piece of the old bacteria’s genome, injecting the antibiotic resistance gene, once again leading to antibiotic resistance.

Question 12

what are transposons?

Answer 12

jumping genes.

mobile genetic elements that transfers DNA within cell.

Question 13

what are insertion sequences/IS elements?

Answer 13

• 150-1500 bp
• Inverted repeats 14-40bp
• Transposase gene

Question 14

what are composite transposons?

Answer 14

• transposase bound by inverted repeat sequences

- central region of extra genes; antibiotic resistance virulence factors

Question 15

how do transposons contribute to antibiotic resistance?

Answer 15

ANSWER

Question 16

what are integrons?

Answer 16

genetic units that are able to capture and carry gene cassetes, by the function of the integrated and recombination sites

Question 17

what do the gene cassettes have?

Answer 17

often they are antibiotic resistant genes. some integrons can have 5 or 6 antibiotic resistant genes.

Question 18

how do bacteria get resistance from integrons?

Answer 18

-when the attC site matches with attL site (via enzymes), the bacteria may shuffle the cassette, allowing it to get resistance to particular antibiotics.

Question 19

what are practices that lead to resistance?

Answer 19

• over-use of antibiotics in medicine, agriculture, vet practices
• 50% of people prescribed antibiotics do not complete treatment of do not take recommended dose.
• consumer demand and antibiotics in animal feed cause resistance

Question 20

why do people not complete treatment or take recommended dose?

Answer 20

• can’t afford full course
• full course not available
• can’t be bothered taking full course

Question 21

strategies to prevent resistance?

Answer 21

1. preventing infections and prevent spread
2. tracking resistance patterns
3. improve the use of antibiotics
4. developing new antibiotics and diagnostic tests

Question 22

how to 1. prevent infections and prevent spread?

Answer 22

hygiene and hand washing, public education, vaccination for preventable diseases.

Question 23

how to 2. track resistance patterns?

Answer 23

-sending specimens for diagnostic and antibiotics susceptibility testing.

Question 24

how to 3. improve the use of antibiotics?

Answer 24

• restrict use of antibiotics
• restrict use in agriculture/aquaculture
• by prescription and only if needed
• advocate
• combination of antibiotics to minimise development of resistance

Question 25

how to 4. develop new antibiotics and diagnostic testing?

Answer 25

• new analogues of existing drugs
• designer antibiotics
• search for natural compounds
• novel approaches (target virulence factors)