Transcript Antibiotic resistant bacteria

The effects of
Antibiotics on the
growth of bacteria intro
http://outreach.mcb.harvard.edu/animations/resistance7.swf
How do bacteria reproduce?
• Binary fission: to divide in half
http://www.ryancshaw.com/Files/micro/Animations/BacterialGrowth/PLAY
_bacterial_growth.html
How do
bacteria
reproduce?
How do bacteria reproduce?
• Parent cell produces genetically
identical daughter cells
–unless mutation changes DNA
(rare but happens)
How do bacteria reproduce?
• Exponential growth
–bacteria at appropriate
temperature w/ nutrients can
reproduce every 20 minutes
How do bacteria reproduce?
• Exponential growth
–In 24 hours 1 cell -->
4,722,400,000,000,000,000,000
How do scientists grow
bacteria?
• Petri Dish with solid agar nutrition
How do scientists grow
bacteria?
• Flask or test tube with liquid nutrients
Antibiotics
• Drugs produced by bacteria or fungi
to treat people with bacterial
infections (does not treat viral
infections)
Antibiotics
• Most antibiotics come from
microorganisms
–chemical warfare to keep foreign
microbes out of territory and away
from food
Antibiotics
• Example: different Streptomyces
strains which naturally grow in soil
produce: streptomycin, erythromycin
and tetracyline
Antibiotic resistant bacteria
• Bacteria that have a gene or
genes that allow them to
survive the antibiotic
Antibiotic resistant bacteria
• How do individual bacteria
develop resistance?
–Random mutation hidden in
genes
Antibiotic resistant bacteria
• And “bacteria sex”– conjugation:
bacteria of different or same species
can exchange pieces of DNA
sometimes including mutation
If mobile plasmid
Includes an
antibiotic resistance
Gene, then the
recipient bacterium
Will transform
into An antibiotic
resistant strain
http://highered.mcgrawhill.com/sites/9834092339/student_view0/chapte
r28/bacterial_conjugation.html
Antibiotic resistant bacteria
• Resistance not always 100%
Antibiotic resistant bacteria
• 2 types of bacteria
–gram (+): stain violet because of
cell wall components
– http://www.microbelibrary.org/microbelibrary/files/ccIm
ages/Articleimages/keen/Gramstainkeen.htm
Antibiotic resistant bacteria
• 2 types of bacteria
–gram (-): stain red because of cell
wall components. This cell wall can
be toxic and more resistant to
antibiotics
Antibiotic resistant bacteria
Lab
Purpose: to determine
which antibiotic is the
most effective in
limiting the growth of
the bacterial species
Bacillus subtilis (that
was grown from a
peppercorn source)
BioRad Modified Kirby-Bauer Test
http://www.cleanvideosearch.com/media/action/yt/watch?videoId=CaeQaAuG9pU