Antimicrobial Agents Flashcards
define antibiotic.
products of microbes that, in dilute solution, inhibit or kill other organisms
describe antimicrobial agents
man made agents which include antibiotics and synthetic compounds that have the same effect - to inhibit or kill other organisms
what is the difference between agents being static or cidal
static - inhibits microbes
cidal - kills microbes
why may you use a static antimicrobial agent rather than cidal?
gives time for the immune system to eliminate the bacteria
- in case cidal can be more harmful
what test can you use to test the susceptibility of bacteria to drugs? describe it.
disc diffusion test
- grow bacteria on agar plate
- place antimicrobial onto them
- incubate
- observe the zones of clearing around the disc where bacteria has been killed
what is the MIC?
minimum inhibitory concentration
the lowest conc of antibiotic that prevents visible growth
what is the MBC?
minimum bactericidal concentration
the lowest concentration of antibiotic that kills particular bacterium
what is an accurate way of determining the MIC and MBC of a bacteriostatic drug?
using test tubes
- control with only bacteria
- control with only antibiotics
- test tubes with varying concentrations of antibiotics
state the concentration levels of test tubes if the concentration halves every time.
1
1/2
1/4
1/8
1/16
1/32
1/64
1/128
give an example of a bacteriostatic drug
erythromycin
give an example of a bactericidal drug
penicillin
why is selective toxicity important?
to not affect the human host, but just the bacteria
but acting upon bacterial reactions not found in human cells
how can you have problems with selective toxicity? give an example.
can develop allergies
penicillin allergy comes from presence of thiazolidine ring in penicillin
why can antiviral, antifungal and anti protist drugs be more toxic to humans?
closer cell structure to human cells
- can cause damage
how do antiviral drugs work?
inhibit transcription factors
ribozymes
- RNA molecules
- tertiary structure confers enzymatic activity
antisense RNA
- short sequence of RNA, complement of mRNA
- binds to specific mRNA
- prevents translation
