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ANTIBIOTICS

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... Sulfonamides Metabolite Inhibition Sulfonamide P-aminobenzoic acid Commonly used antibiotic types Penicillins Cephalosporins ... Mode of action is enzyme ... – PowerPoint PPT presentation

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Title: ANTIBIOTICS


1
ANTIBIOTICS
  • From the Greek
  • anti - against
  • bios - life

2
Chemotherapy
  • Paul Ehrlich
  • Use of chemical agent to kill bacteria and not
    harm the host
  • Search for the Magic bullet
  • Developed an arsenic compound that killed the
    bacteria that causes syphilis
  • Compound was called salvarsan but was quite toxic
    to the host

3
Antibiotics
  • Natural compounds produced by microorganisms that
    inhibit the growth of other microbes
  • Majority of antibiotics come from Streptomyces
    bacteria and molds
  • Over 100 different antibiotics
  • Antibiotics generally have two names
  • Brand name created by the drug company
  • Generic name based on the chemical structure or
    class of antibiotics

4
Famous penicillin picture
5
Alexander Fleming
  • Discovered penicillin by accident in 1928
  • A mold contaminating a plate of Staphylococcus
    aureus showed anti-bacterial properties
  • The mold was identified as a member of genus
    Penicillum, hence the name for the naturally
    produced antibiotic
  • Fleming won the Nobel prize in 1945 for this
    discovery, shared with Howard Florey and Ernst
    Chain

6
Penicillin
  • Wonder drug
  • Killed bacteria with few side effects on the
    patient
  • SELECTIVE TOXICITY
  • Penicillin was NOT the first anti-bacterial
    compound
  • Penicillin was the FIRST natural compound that
    kills bacteria
  • Antibiotic
  • Not made in the lab

7
Spectrum of Activity
  • Broad spectrum antibiotics
  • Effect both G and G- bacteria
  • Tetracycline
  • Narrow spectrum antibiotics
  • Effects fewer types of pathogens
  • More selective?
  • Penicillin best against G bacteria

8
How do antibiotics work?
9
Cell Wall Synthesis
  • Penicillin
  • Prevents synthesis of the peptidoglycan
    components of the cell wall
  • Targets actively growing cells
  • Very little toxicity to human cells

10
Inhibition of protein synthesis
  • Broad spectrum of activity all bacteria have to
    make proteins
  • Difference in ribosome size in bacteria accounts
    for selective toxicity
  • Chloramphenicol, erythromycin (G), streptomycin,
    tetracyclines

11
Injury to plasma membrane
  • Changes to permeability of membrane causes loss
    of metabolites
  • Polymyxin B

12
Inhibition of nucleic acid synthesis
  • Inhibition if either DNA replication or mRNA
    synthesis
  • Toxicity problems
  • Rifampin mRNA blocker
  • Nofloxacin and ciprofloxacin DNA synthesis
    blockers

13
Inhibition of synthesis of essential metabolites
  • Block enzyme activity
  • Competitive inhibition of enzyme activity
  • PABA (para-aminobenzoic acid) competition
  • Sulfonamides

14
Metabolite Inhibition
  • Sulfonamide
  • P-aminobenzoic acid

15
Commonly used antibiotic types
  • Penicillins
  • Cephalosporins
  • Animoglycosides
  • Macolides
  • Sulfonamides
  • Fluoroquinolones
  • Tetracyclines
  • Polypeptides

16
Penicillin
  • Destroys the cell wall of bacteria
  • Best against G bacteria during active growth
  • Examples
  • Penicillin G
  • Penicillin V
  • Ampicillin
  • Amoxicillin

17
Cephalosprorins
  • Similar to penicillin - interferes with cell wall
    formation
  • Used when patient is allergic to penicillin
  • Examples
  • Cefadroxil
  • Cephapirin
  • Cephalexin
  • Cephalothin

18
Aminoglycosides
  • Inhibition of protein synthesis in bacteria
  • Some toxic reactions possible in kidney and liver
  • Examples
  • Gentamicin
  • Streptomycin
  • Neomycin

19
Macrolides
  • Interfere with bacterial protein synthesis
  • Commonly given to patients that are sensitive to
    penicillin
  • Gastrointestinal discomfort is a common side
    effect
  • Examples
  • Azithromycin
  • Erthromycin

20
Sulfonamides
  • Very early antimicrobial substance
  • Commonly called sulfa drugs
  • Developed in the 1930s in Germany
  • Mode of action is enzyme inhibition
  • Allergy to sulfa is common

21
Fluoroquinolones
  • Large class of semi-synthetic broad spectrum
    antibiotics
  • Inhibition of bacterial DNA replication
  • Few side effects, well tolerated
  • Examples
  • Ciprofloxacin
  • Norfloxacin

22
Tetracycline Antibiotics
  • Members of this group of antibiotics are produced
    by Streptomyces group of bacteria
  • Inhibition of protein synthesis
  • Used commonly to treat acne
  • Examples
  • Tetracycline
  • Deoxycycline

23
Penicillin
24
Penicillinase
25
Cephalosporin and Penicillin
  • Cephalosporin
  • Produced from a fungus
  • Similar in action to penicillin
  • More active against G- bacteria
  • More resistant to penicillinase
  • Penicillin
  • Produced from fungus
  • Inhibits cell wall synthesis
  • Effective against mostly G bacteria
  • Penicillinase sensitivity

26
Cephalosporin and Penicillin
27
Adverse reactions
  • Toxicity
  • Allergy
  • Disruption of natural flora
  • Yeast infections

28
Antibiotic Resistance(A BIG problem)
  • Resistance is acquired by mutation
  • R (resistance) plasmids acquired by bacterial
    conjugation
  • How to limit resistance
  • Take all your pills, dont stop when you feel
    better
  • Use antibiotics only when necessary
  • NEVER take antibiotics for viral infection alone

29
Nosocomial Infections
  • Infections acquired while in a health care
    facilities
  • CDC estimates 2 million people per year get these
    infections
  • 90,000 deaths per year

30
Nosocomial Infections
31
Antiviral Drugs
  • Limited in number
  • Targets for these drugs are viral reproduction
  • Nucleotide analogs are the most commonly used
    agents disrupt viral nucleic acid replication
  • Acyclovir

32
Nucleotide analog
33
Sensitivity Testing
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