Antibiotika Evi 2012

8/12/2019 Antibiotika Evi 2012

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2008

ANTIBIOTIKAEvi Umayah Ulfa


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Antimicrobial Drugs

Chemotherapy The use of drugs to treat adisease

Antimicrobial drugs Interfere with the growth ofmicrobes within a host

Antibiotic Substance produced by amicrobe that, in small amounts,inhibits another microbe

Selective toxicity A drug that kills harmful microbes

without damaging the host


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Table 20.1

MicrobialSources of

Antibiotics


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Table 20.2

Antibiotic Spectrum of Activity

No antibiotic is effective against all microbes


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Mode of Antimicrobial Action

Bacteria have their own enzymes for

Cell wall formation

Protein synthesis

DNA replication

RNA synthesis

Synthesis of essential metabolites


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Mode of Antimicrobial Action

Figure 20.2


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Inhibition of Cell Wall Synthesis


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Beta Lactam Antibiotics (Penicillins)

B-lactams inhibittranspeptidase.

Only effective againstrapidly growing organismsthat synthesizepeptidoglycan. (Ineffectiveagainst mycobacteria.)


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Penicillin

Penicilinase-resistant penicillins

Extended-spectrum penicillins

Penicillins + -lactamase inhibitors

Carbapenems

Monobactam

Inhibitors of Cell Wall Synthesis


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Figure 20.8

Cincin beta laktam AB penisilin dirusak oleh enzim penisilinase


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Cephalosporins

2nd, 3rd, and 4th

generations moreeffective against

gram-negatives

Antibacterial AntibioticsInhibitors of Cell Wall Synthesis

Figure 20.9


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Polypeptide antibiotics

Bacitracin

Topical application

Against gram-positives

Inhibits regeneration of phospholipids receptorsinvolved in peptidoglycan synthesis.

Vancomycin Glycopeptide

Important "last line" against antibiotic resistant S.aureus



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Antimycobacterium antibiotics

Isoniazid (INH)

Inhibits mycolic acid synthesis Ethambutol

Inhibits incorporation of mycolic acid



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Inhibition of Protein Synthesis (Translation)

Figure 20.4


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Chloramphenicol Broad spectrum

Binds 50S subunit, inhibits peptide bondformation

Aminoglycosides

Streptomycin, neomycin, gentamycin

Broad spectrum

Changes shape of 30S subunit

Inhibitors of Protein Synthesis


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Tetracyclines Broad spectrum

Interferes with tRNA attachment

Macrolides Gram-positives

Binds 50S, prevents translocation

Erythromycin

Gram-positives

Binds 50S, prevents translocation

Inhibitors of Protein Synthesis


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Polymyxin B

Bacillus polymyxa(PolimixinA,B,C, and D)

Decapeptide that disrupts the phospholipidlayer incell membrane

Topical

Combined with bacitracin and neomycin in over-

the-counter preparation

Injury to the Plasma Membrane


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Rifamycin Inhibits RNA synthesis

Antituberculosis

Quinolones and fluoroquinolones (DNA Synthesis) Ciprofloxacin

Inhibits DNA gyrase

Urinary tract infections

Inhibitors of Nucleic Acid Synthesis


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Sulfonamides (Sulfa drugs)

Inhibit folic acid synthesis

Broad spectrum

Inhibitions of Sythesis os Essential Metabolites

Figure 5.7


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Figure 20.13

Inhibitions of Sythesis os Essential Metabolites


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Classes of Antibiotics

Lactam AB

Macrolide AB

Tetracyclines

Aminoglycoside AB

Polypeptide AB

Lyncosamide

Chloramphenicol

Rifamycins

Minor AB


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Polyenes

Amphotericin B Azoles

Miconazole

Triazoles Allylamines

Antifungal DrugsInhibition of Ergosterol Synthesis

Figure 20.15


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Echinocandins

Inhibit synthesis of -glucan

Cancidas is used against Candida andPneumocystis

Antifungal DrugsInhibition of Cell Wall Synthesis


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Flucytocine

Cytosine analog interferes with RNA synthesis

Pentamidine isethionate

Anti-Pneumocystis; may bind DNA

Antifungal DrugsInhibition of Nucleic Acids


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Griseofulvin

Used for superficial mycoses

Tolnaftate

Used for athlete's foot; action unknown

Antifungal DrugsInhibition of Microtubules (Mitosis)


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Antiviral DrugsNucleoside and Nucleotide Analogs

Figure 20.16a


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Antiviral DrugsNucleoside and Nucleotide Analogs

Figure 20.16b, c


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Protease inhibitors Indinavir

HIV

Inhibit attachment

Zanamivir

Influenza

Inhibit uncoating

Amantadine Influenza

Interferons prevent spread of viruses to new cells

Viral hepatitis

Antiviral DrugsEnzyme Inhibitors


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Chloroquine Inhibits DNA synthesis

Malaria

Metronidazole Damages DNA

Entamoeba, Trichomonas

Antiprotozoan Drugs


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A ih l i hi


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Mebendazole

Inhibits nutrient absorption

Intestinal roundworms

Ivermectin

Paralyzes worm

Intestinal roundworms

Antihelminthic Drugs

Di k Diff i T


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Disk-Diffusion Test

Figure 20.17

Metode untukmenguji kepekaan

AB

E TMetode untuk


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E Test

Figure 20.18

Metode untuk

menguji kepekaan

AB

B h Dil i TMetode untuk


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Broth Dilution Test

Figure 20.19

Metode untuk

menguji kepekaan

AB

Hasil Uji Kepekaan Antibiotik


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Diameter Hambat

MIC Minimal inhibitory concentration

Kadar minimal AB yang mampu menghambatMO

MBC Minimal bactericidal concentration

Kadar Minimal AB yang mampu membunuhMO

Hasil Uji Kepekaan Antibiotik

A tibi ti R i t


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A variety of mutations can lead to antibiotic resistance.

Mechanisms of antibiotic resistance

1. Enzymatic destruction of drug

2. Prevention of penetration of drug

3. Alteration of drug's target site

4. Rapid ejection of the drug

Resistance genes are often on plasmids or

transposons that can be transferred between bacteria.

Antibiotic Resistance

A tibi ti R i t


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Misuse of antibiotics selects for resistance mutants.

Misuse includes:

Using outdated, weakened antibiotics

Using antibiotics for the common cold and other

inappropriate conditions

Use of antibiotics in animal feed

Failure to complete the prescribed regimen

Using someone else's leftover prescription

Antibiotic Resistance

Eff t f C bi ti f D


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Synergism occurs when the effect of two drugs

together is greater than the effect of either alone.

Antagonism occurs when the effect of two drugs

together is less than the effect of either alone.

Effects of Combinations of Drugs

Eff t f C bi ti f D


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Effects of Combinations of Drugs

Figure 20.22

Th F t f Ch th ti A t


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Antimicrobial peptides

Broad spectrum antibiotics from plants and animals

Squalamine (sharks)

Protegrin (pigs)

Magainin (frogs)

Antisense agents

Complementary DNA or peptide nucleic acids thatbinds to a pathogen's virulence gene(s) and

prevents transcription

The Future of Chemotherapeutic Agents

Antibiotika Evi 2012

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