intro to antibiotics and resistance

Question 1

outline a classification of antimicrobials

Answer 1

antibacterial
antiviral
antifungal
amtiprotozoal

Question 2

how can antibacterials be classified

Answer 2

• bactericidal(will kill bacteria) or bacteriostatic (stop bacteria from growing)
• broad or narrow spectrum - broader the spectrum the more conditions we can use it for but this can destroy normal flora.
• target site (mechanism of action )
• chemical structure(antibacterial class)

Question 3

what are the different ways to measure antibiotic activity

Answer 3

1) disc sensitivity /diffusion test-putting the organism on the agar plate and putting paper discs contains antibiotics and reading the zone of clearance.
2) minimum inhibitory concentration(MIC)- the first concentration of antibiotic that inhibits growth of bacteria. done via :broth micro dilution or e-test strip.

Question 4

what are the types of resistance

Answer 4

intrinsic- naturally resistant to the antibiotic. antibiotic does not target specific characteristics of the bacteria so unable to gain access to bacteria.
acquired- occurs when a particular micro-organism obtains the ability to resist the activity of a particular antimicrobial agent to which it was previously susceptible. change is permanent and via chromosomal gene mutation/horizontal gene transfer (via plasmids)
adaptive - organism repsonds to a stress (e.g subinhibitory level of antibiotic )

Question 5

what are the mechanisms of resistance against antibiotics

Answer 5

• enzymatic modification or destruction of antibiotics
• enzymatic alteration of antibiotic targets
• mutations of bacterial target sites

Question 6

how resistance genes are shared

Answer 6

horizontal gene transfer
-bacteria with plasmid can extend a plus which enables a single strand of the plasmid DNA to unwind & be transferred across to the bacteria without the plasmaid.
plasmid carries resistant genes