Ch 10 Flashcards
Know the overall goal of antimicrobial chemotherapy development.
Administer a drug to an infected person that destroys the
infective agent without harming the host’s cells
Be able to describe the Kirby Bauer test.
- Label both of your agar plates with your initials and
species of bacteria. Label one plate “Ex.16” and the
other plate “Ex.17.” - You need to make a lawn of bacteria (see Fig.
16.1). Dip a sterile swab in the broth culture of
bacteria and press the swab against the inside wall of
the tube so it isn’t dripping wet. - Starting at the top of the plate, run the swab back
and forth over the agar until the swab has covered
every part of the agar’s surface. - Turn the plate 90° and run the swab (do not re-dip in
the culture) over the agar perpendicular to your first
streaks, again completely covering the entire plate. - Turn the plate 45° so that your third set of streaks are at an angle in between the first two sets of
streaks, again completely covering every square millimeter of agar (you should have streaked across
every spot on the plate three times, ensuring complete coverage). - Run the swab around the outer edge of the agar.
- Discard the used swab in the biohazard bucket, and repeat steps 2-6 to make a bacterial lawn on
your other plate - Sterilize your tweezers by dipping the ends in the ethanol and flaming them using the Bunsen
burner; do not leave the tweezers in the flame, remove them as soon as the ethanol is on fire. Wait
for the fire to burn out, being careful not to drip flaming ethanol on the benchtop. - Use the sterile tweezers to obtain a sterile filter paper disk. Dip the disk halfway into a container of
disinfectant so that the liquid adsorbs up the disk the rest of the way. You should not dip the entire
disk in the disinfectant or it will become too wet. - Gently place the disk containing disinfectant on your agar plate (Fig. 17.1), and label on the
bottom of the plate the disinfectant used for that disc. - Repeat steps 8-11 for 3-4 more disinfectants, spacing the disks as far apart from each other as
possible and not close to the edge of the plate. - Invert the plate and put it in the class tub for incubation (37°C 18-24h).
Figure 16.1. Making a lawn of
bacteria using a sterile swab.
Know the goals of antimicrobial drugs
disrupt cell
processes or structures of bacteria, fungi, protozoa
Know the goals of antimicrobial drugs
inhibit virus
replication
Know the goals of antimicrobial drugs
interfere with the function of enzymes required to
synthesize or assemble macromolecules
Know the goals of antimicrobial drugs
destroy structures
already formed in the cell
Know the goals of antimicrobial drugs
selectively toxic
kill or inhibit microbial cells without damaging host tissues
4 things a drug must be able to do
be able to administer
be absolutely toxic to the infectious agent
be absolutely nontoxic to the host
remain active in the body
antimicrobial resistance can occur one of 3 ways
- spontaneous mutations in
critical chromosomal genes
**antimicrobial resistance can occur one of 3 ways*
- acquisition of entire new genes or sets of genes via
horizontal transfer from another species
**antimicrobial resistance can occur one of 3 ways*
- slowing or stopping of metabolism so that the
microbe cannot be harmed by the antibiotic (“persisters”)
how antibiotic resistance happens
- lots of bacteria; a few are drug resistant
- antibiotics kill bacteria causing the illness as well as good bacteria protecting the body from infection
- the drug-resistant bacteria are now allowed to grow and take over
- some bacteria give their drug resistance to other bacteria causing more problems
Be able to discuss ways we can do to help us out against the evolving drug resistance threats.
prebiotics
encourages growth of beneficial microbes in the intestine
Be able to discuss ways we can do to help us out against the evolving drug resistance threats.
probiotics
can replace microbes lost during the antimicrobial therapy
Be able to discuss ways we can do to help us out against the evolving drug resistance threats.
fecal transplant
transfer of feces from a healthy patient via colonoscopy
