Antimicrobial Therapy - PowerPoint PPT Presentation

About This Presentation
Title:

Antimicrobial Therapy

Description:

Antimicrobial Therapy * All invasive medical devices support the development of biofilms. Biofilm is a complex three-dimensional structure that consists of cells ... – PowerPoint PPT presentation

Number of Views:188
Avg rating:3.0/5.0
Slides: 58
Provided by: mediaWix62
Category:

less

Transcript and Presenter's Notes

Title: Antimicrobial Therapy


1
Antimicrobial Therapy
2
Antimicrobial Therapy
  • Chemotherapy
  • Antimicrobial drugs act by interfering with the
    __________________, but they must do so
    ___________________(compared to a disinfectant
    which can work __________).

3
Antimicrobial Therapy
  • The advent of antimicrobial therapy has
    dramatically __________ the life span and quality
    of life for humans.
  • More people have died ___________than have died
    from ___________.

4
When did antimicrobial therapy originate?
  • Many ancient cultures have used antimicrobials
    from ______________.
  • First systematic attempt to find specific
    antimicrobials occurred in the __________.

5
History of Chemotherapy
  • 1910--_________, father of chemotherapy,
    discovered that Salvarsan could treat _______.
  • 1935Discovered ___________.
  • 1928-40_________________action from the mold,
    ___________, however many years passed before
    penicillin was purified and produced.

6
(No Transcript)
7
Antimicrobial Drugs
  • Antibiotic

8
  • Note more than half of the antibiotics produced
    are derived from __________, a bacteria found in
    soil, hence many researchers are looking for more
    possible antibiotics in __________, etc.

9
Narrow-spectrum vs. Broad-spectrum antibiotics.
What is Penicillin?Note Is it easier to treat
prokaryotic or eukaryotic infections?
10
What is the ideal antimicrobial?
  • _____________ idea by Paul Ehrlich
  • Selective toxicity--gt the ideal drug kills
    _______________________.
  • Solubility in body fluids
  • Selective toxicity
  • Toxicity not easily altered
  • ____________
  • Stability maintenance of a constant, therapeutic
    concentration in blood and tissue fluids
  • Resistance to microorganisms not easily acquired
  • ________shelf life
  • Reasonable cost

11
The Action of Antimicrobial Drugs
  • Bactericidal
  • ___________
  • Bacteriostatic
  • __________
  • Antimicrobial Drugs have Different Mechanisms
  • 1.
  • 2.
  • 3. Inhibition of Protein Synthesis
  • 4.
  • 5.

12
The Action of Antimicrobial Drugs
13
Inhibition of Cell Wall Synthesis Note the
cell wall is a good, selective target since
eukaryotes dont have peptidoglycanExample
Penicillin, bacitractin, cephalosporin, vancomycin
14
Actions of Antimicrobial Drugs (cont.)
  • Inhibition of Protein Synthesis
  • exploit difference in ribosomes
  • prokaryotic ribosomes 70S ribosomes
  • eukaryotic ribosomes 80S ribosomes
  • Erythromycin, Streptomycin, Tetracycline,
    Chloramphenical
  • some toxicity since mitochondria have 70S
    ribosomes
  • Injury to the Plasma Membrane
  • change in permeabiblity of plasma membrane causes
    loss of important metabolites from cell
  • polymyxin

15
Actions of Antimicrobial Drugs (cont.)
  • Inhibition of Nucleic Acid Synthesis
  • inhibit transcription, translation
  • some toxicity because of interference
  • Rifamycin, quinolone
  • Inhibition of Essential Metabolite Synthesis
  • drugs can work as competitive inhibitors of
    important enzyme reactions
  • sulfanilimide

16
Actions of Antimicrobial Drugs
  • Treatment of eukaryotic pathogens is
    _____________because they are more similar to
    human cells.
  • Need to target the few differences between cells.
  • Sterols in cell membrane in fungi
  • Treatment of viral pathogens is also difficult
    because viruses ____________the human cell.
  • Need to target the viral multiplication cycle
  • attachment, ________ uncoating, __________,
    maturation, release

17
Bioavailability of Chemotherapeutics
  • The chemical structure of a drug AND the mode of
    entry of a drug influence
  • a)
  • b)

18
Tests to Guide Chemotherapy
  • Disk-Diffusion Method

19
The Effectiveness of Chemotherapeutic Agents
  • Effects of Combinations of Drugs
  • Note need to be careful of how you take the
    drug(grapefruit juice effect) and if you are
    taking any drugs that could interfere with the
    activity of the prescribed antibiotic(synergism
    or antagonism).
  • The Future of Chemotherapeutic Agents
  • Many diseases have become resistant to
    antibiotics.
  • Chemicals produced by plants and animals are
    providing new antimicrobial agents.

20
(No Transcript)
21
The Future of Chemotherapeutic AgentsMany
diseases have become resistant to antibiotics.
Some drugs are actually a combination of 2 drugs.
This nifty example shows an ingenious way to
start with one antibiotic and then if it is being
degraded a second one can be released.
22
Antibiotic Resistance
  • Nature
  • What is antibiotic resistance?
  • How do bacteria resist antibiotics?
  • Sources
  • How does antibiotic resistance originate?
  • How is antibiotic resistance propagated?
  • Clinical Significance
  • How does antibiotic resistance affect us?
  • How can we prevent antibiotic resistance?

23
Antibiotic Resistance
  • How is antibiotic resistance propagated?
  • Bacteria transfer antibiotic resistance and we
    exacerbate the problem by adding selective
    pressure
  • Clinical Significance
  • How does antibiotic resistance affect us?
  • Renders antibiotics ineffective and subjects us
    to serious consequences, perhaps death.
  • How can we prevent antibiotic resistance?
  • Use ICPs and antibiotics wisely

24
What is Antibiotic Resistance?
  • Antibiotic Resistance ____________________________
    ______
  • Common example
  • child is prescribed amoxicillin for an ear
    infection, however there is no improvement in
    condition. Why?

25
How do Bacteria Resist Antibiotics?
  • Here are a few examples of the mechanisms of
    resistance. Some bacteria may
  • 1.
  • Streptomycin targets bacterial ribosomes. If
    ribosomes change in structure, can streptomycin
    inhibit translation?
  • 2.
  • If antibiotics can not enter the cell, will they
    be effective?
  • 3.
  • If a beta-lactamASE (aka penicillinASE) enzyme is
    produced, what will happen to penicillin?

26
Beta-lactamase breaks the beta-lactam ring and
renders penicillin inactive
27
How does antibiotic resistance originate?
  • Antibiotic resistance originates as a consequence
    of genetic change.
  • Bacteria change their genetic makeup in 2 ways
  • ____________ genetic change
  • Mutations normally occur every million base
    pairs. Since microbes can multiply rapidly
    (GT20min) many genetic changes can occur.
  • ________________ genetic change
  • Microbes can transfer genetic information in many
    ways which we will review
  • Some use Resistance plasmids (R plasmids or R
    factors)
  • Some R plasmids carry 6-7 different resistance
    genes

28
Resistance plasmids can carry many resistance
genes
  • YIKES! We now have a super bug!

29
Can antibiotic resistance be transferred?
  • Yes! We transferred antibiotic resistance in
    lab! Remember how easy it was to transform
    bacteria with an ampicillin resistant plasmid and
    then select for the recombinant bacteria by
    plating on TSAampicillin?
  • A reminder of the different ways bacteria
    transfer genetic information
  • 1.
  • 2.
  • 3.
  • 4.

30
Transformation(______________________)
  • If gene a or gene b codes for penicillinase will
    the new recombinant bacterium be killed by
    penicillin treatment?

31
2. Transduction(______________________)
  • If the purple or red gene is penicillinase, will
    the new recombinant bacterium be killed by
    penicillin?

32
3. Conjugation(____________________________)
  • If the red plasmid contains a penicillinase
    gene, will the recipient bacterium be killed by
    penicillin?

33
How does antibiotic resistance originate?
Susceptible Bacteria
34
  • Bacteria have evolved numerous mechanisms to
    evade _________.
  • Chromosomal mutations are an important source of
    ________ to some antimicrobials.

35
  • Acquisition of resistance genes or gene clusters,
    via ________, _________, or __________, accounts
    for most antimicrobial resistance among bacterial
    pathogens.
  • These mechanisms also enhance the possibility of
    _______________.

36
How are Antibiotic Resistant Strains Propagated?
  • ________________causes pressure to select
    resistant strains.
  • _______________, selective pressure decreases and
    antibiotic resistance genes may be _______.

37
  • Do antimicrobials cause mutations? __________.
  • Once resistant strains of bacteria are present in
    a population, ____________.
  • ________ antimicrobial selection pressure is one
    key to preventing _________ _________and ________
    the utility of available drugs for as long as
    possible.

38
Clinical Implications in the Development of Drug
Resistant Staphylococcus aureus
Penicillin
Penicillin-resistant
S. aureus
1950s
S. aureus
  • How do we treat S. aureus infections when they
    become completely resistant to our last line
    antibiotic, Vancomycin?

39
How does Antibiotic Resistance affect us?(More
clinical implications)
  • When microbes develop resistance to antibiotics
    we can no longer treat bacterial diseases.
  • What other types of diseases do we have a
    difficult time treating?
  • Complete antibiotic resistance will be equal to
    not having antibiotics at all.
  • Before the discovery of antibiotics, millions of
    people died of diseases that we can treat today.
  • Unfortunately, antibiotic resistance __________.

40
Antibiotic Resistance is Prevalent and Rising
Methicillin-resistant Staphylococcus aureus(MRSA)
Vancomycin-resistant Enterococci (VRE)
Non-Intensive Care Unit Patients Intensive Care
Unit Patients
Source National Nosocomial Infections
Surveillance (NNIS) System
  • Can hospitals be dangerous for patients?

41
  • The proportion of pathogens causing
    hospital-onset infections that are resistant to
    target antimicrobial drugs continues to
    __________ at an alarming rate!!
  • Currently, more that _____of Staphylococcus
    aureus isolates causing infections in
    _________are resistant to methicillin more than
    _____are resistant in other hospital units.

42
  • Vancomycin-resistant enterococci (VRE) emerged in
    the late 1980s and are now _______ in many
    hospitals.
  • In many hospitals, more than 25 of enterococcal
    infections are caused by vancomycin-resistant
    strains.

43
How can we prevent antibiotic resistance?
  • 1. Prevent infection
  • _____________
  • 2. Diagnose and treat infection effectively
  • ____________
  • Use effective antibiotics
  • 3. Use antimicrobials wisely
  • __________________
  • Stop feeding antibiotics to livestock
  • 4. Prevent transmission
  • Wash your hands (Soap, alcohol gel)
  • __________________

44
  • These 4 strategies ________, ______________,
    ___________, and _____________- form the
    framework for CDCs Campaign to Prevent
    Antimicrobial Resistance.

45
  • Clinicians and their patient care partners hold
    the solution to integrating these strategies into
    daily practice and optimizing the care and safety
    of all patients.

46
Treat microbes with effective antibiotics
Choose the antibiotic that gives the largest zone
of inhibition.Would you choose the top or the
bottom chemical?
47
(No Transcript)
48
Take the full course of antibiotics to decrease
resistance
49
Selective media identifies genetic resistance.
Selective media identifies genetic resistance,
BUT does not create it. However, selection can
result in an ______________________.
50
Wash your hands OR use an alcohol based hand rub!
  • At home, should you wash your hands with
    anti-bacterial soap? Why or why not?

51
  • In this scanning electron micrograph, many
    bacteria are seen in a matrix of material that
    also contains a red blood cell.
  • This biofilm developed within 24 hours of
    catheter insertion.
  • Biofilms may promote development of
    antimicrobial-resistant infections in several
    ways

52
  • Serving as a _____ for deposition and growth of
    _________that then are released to cause
    ___________
  • Creating a __________to antimicrobial diffusion,
    so that bacteria imbedded in the biofilm may be
    exposed to sub-inhibitory concentrations of
    _________________ ___________________

53
  • Providing a _________ in which bacteria can
    _____________.
  • Biofilms cannot be _______ but some strategies
    may decrease the rate at which biofilms are
    formed and decrease bacterial colonization of
    biofilms.

54
Are these bacteria resistant to antibiotics?
Scanning Electron Micrograph
55
(No Transcript)
56
Want to know more about Antibiotic Resistance?
  • Visit the following websites
  • http//www.microbeworld.org/htm/cissues/resist/res
    ist0.htm
  • http//www.cdc.gov/drugresistance/index.htm
  • http//www.who.int/csr/resources/publications/drug
    resist/antibiotics.pdf
  • http//www.fda.gov

57
Closing Thoughts
  • Does antibiotic resistance scare you?
  • Luckily, we still have time to prevent the spread
    of antibiotic resistance.
  • How can you help prevent the spread of antibiotic
    resistance?
  • The good news
  • Remember that most bacteria are beneficial and
    only a small proportion cause disease.
Write a Comment
User Comments (0)
About PowerShow.com