Antibiotic Resistance Flashcards
What is resistance?
when a previously susceptible organism is no longer inhibited by an antibiotic at levels that can be safely acheived clinically
What can intermediate resistance be treated with?
increase from the standard dose
What is the theraputic index?
the differnce between the dose necessary for treatment and that causing harm
What is intrinsic resistance?
when all strains of a species are resistant
What is the minimum inhibitory concentration (MIC)
lowest concentration of antibiotic that completely inhibits the growth od a bacterium
Minimum bactericidal concentration (MBC) =
is the lowest dose that completely kills bacterium
What is the antibiotic breakpoint?
a concentration chose for laboratory testing that will differentiate sensitive from resistant populations of bacteria
When does breakpoint vary?
will vary for each of the species tested due to their differing intrinsic resistance/susceptibility
What defines the breakpoint?
- Distribution of MICs of target bacteria
- Achievable therapuetic concentration in tissues
- maximum achievable concentrations
What is EUCAST used for?
- take strains of organism and test them against drugs
- indicate therapuetic range of drugs
What is streptococci resistant to and why?
Naturally resistant to aminoglycosides
MIC is above the concentration that causes toxicity
What is pseudomonas spp. resistant to and why?
normally resistant to beta lactams
intrinsic beta-lactamases, but can be overcome by design
What does mycoplasma spp. resistance to and why?
resistant to beta-lactam antibiotics
cell wall has no peptidoglycan
What is enterobacteriaceae resistant to and why?
metronidazole
faculative anaerobes - they grown in aerobic conditions
