Session 4- Introduction to Antibiotics and Resistance Flashcards
bactericidal
kill the bacteria
bacteriostatic
stop the bacteria from reproducing
how to choose an antibiotic
is it active against target organism does it reach site of infection is it available in the right formulation what is the half life does it interact with other drugs are there toxicity issues does it require therapeutic drug monitoring does your patient have an allergy to any antibiotic class
what are the different ways to measure antibiotic resistance
Disc sensitivity/Diffusion testing- putting the organism on the agar plate and putting paper discs containing antobiotics and reading the zone of clearance
Minimum inhibitory clearance- the first concentration of antobiotic that inhibits the growth of bacteria,
what is intrinsic antibiotic resistance
a bacterial species is naturally resistant to a certain antibiotic or family of antibiotics, without the need for mutation or gain of further genes. The antibiotic does not that target the specific characteristics of the bacteria, therefore, unable to gain access to bacteria- this is usually a permanent ‘resistance’.
what is acquired antibiotic resistance
occurs when a particular microorganism obtains the ability to resist the activity of a particular antimicrobial agent to which it was previously susceptible
usually permanent and via chromosomal gene mutation/horizontal gene transfer
mechanisms for acquired antibiotic resistance
- enzymatic modification or destruction of antibiotics
- enzymatic alteration of antibiotic targets or mutation of bacterial target sites
- overexpression of efflux pumps
adapted antibiotic resistance
This only causes a mild stress response to the bacteria- hence it will respond by becoming resistant to the antibiotic
antifungals
azoles
polyenes
antivirals
aciclovir
oseltamivir
metronidazone
anti bacterial and anti protozoal
beta-lactam antibiotics
prevent cell wall synthesis pennicilin, carbapenem, cephalosporin
what is antimocrobial stewardship
coordinated interventions designed to improve and measure the appropriate use of antimicrobials by promoting the selection of teh optimal antimicrobial drug regimen, dose, duration of therapy, and route of administration.
Antimicrobial stewards seek to achieve optimal clinical outcomes related to antimicrobial use, minimize toxicity and other adverse events, reduce the costs of health care infections, and limit the selection for antimicrobial resistant strains
MDR
multi drug resistant- non-susceptibility to at least one agent in three or more antimicrobial categories
XDR
extensively drug resistant- non-susceptibility to at least one agent in all but two or fewer antimicrobial categories
PDR
pan-drug resistant - non susceptibility to all agents in all antimicrobial categories
name a penicllin
amoxicillin
name a cephalosporin
cefadroxil
name a tetracycline
tetracycline
name a aminoglycoside
gentamicin
name a macrolide
erythromycin
name a sulfonamide
co-trmixazole
name a quinolone
ciprofloxacin
how does penicillin work
burst bacterial cell walls by acting directly on peptidoglycand which play an essential role in cell walls of bacter
how do cephalosporins work
bactericidal (kill bacteria) and work in a similar way to penicillins. They bind to and block the activity of enzymes responsible for making peptidoglycan, an important component of the bacterial cell wall.
how do tetracyclines work
Tetracycline is a short-acting antibiotic that inhibits protein synthesis
how do aminoglycosides work
Aminoglycosides inhibit protein synthesis by binding, with high affinity, to the A-site on the 16S ribosomal RNA of the 30S ribosome
how do macrolides work
inhibit protein synthesis
how do sulfonamides work
binding and inhibiting a specific enzyme called dihydropteroate synthase (DHPS). This enzyme is critical for the synthesis of folate, an essential nutrient
how do quinolones work
inhibit replication of bacterial DNA by blocking the ligase domain of bacterial DNA gyrase (topoisomerase II); some also inhibit topoisomerase IV.
Bactericidal
which antibacterials affect cell wall synthesis
beta-lactams- penicillins, cephalosporinsn
glycopeptides
which antibacterials affect protein synthesis
tetracycline
aminoglycosides
macrolides
what antibacterials affect cell membrane function
polymixins- colistin
what antibacterials affect nucleic acid synthesis
quinolones
trimethoprim
rifampicin
what is disc sensitivity testing
putting the organism on a agar plate and putting paper discs containing antibiotics and reading the zone of clearance
what is MIC
minimum inhibitory concentration- the first concentration of antibiotic that inhibits the growth of bacteria
