ANTIMIKROBA -Dian Natasya-
ANTIMIKROBA-Dian Natasya-
Referensi
Tortora GJ, Funke BR, Case CL. 2001. Microbiology an Introduction, 7th edition. Benjamin Cummings, San Francisco,
CA 94111, USA
Lllmann, 2000, Color Atlas of Pharmacology, Thieme, New York
Bauman BR, Machunis-Masuoka E, Tizard I, 2007, Microbiology with Disease by Taxonomy, 2nd edition,
Pearson Benjamin Cumming, San Francisco, USA
Todar K, 2009, Antimicrobial Agents in the Treatment of Infectious Disease, Available from:
http://www.textbookofbacteriology.net/antimicrobial
Sejarah dan Definisi
Paul Erlich (1854-1915)
Chemotherapy: penggunaan bahan kimia yang secaraselektif membunuh patogen, tanpa efek/ dengan efek yang
ringan terhadap pasien
1928: Alexander Fleming
The growth of Staphylococcus aureus was inhibited in the area surrounding the colony of a mold that have
contaminated a Petri plate Penicillium notatum
Antibiotik: bahan yg dihasilkan oleh mahluk hidup
yg dapat membunuh/menghambat pertumbuhan
mikroorganisme lain.
Antibiotics ~ antibacterial
Mikroorganisme penghasil antimikroba
Bacillus subtilis Bacitracin
B. polymyxa Polymyxin
Streptomyces venezuelae Chloramphenicol
S. aureofaciens Chlortetracycline & tetracycline
S.nodosus Amphotericin B
S.erythraeus Erythromycin
S.fradiae Neomycin
S.griseus Streptomycin
Micromonospora purpurea Gentamycin
Cephalosporium spp. Cephalotin
Penicillium griseofulvum Griseofulvin
Selective toxicity
Selective toxicity
antibiotics must be highly effective against the microbe but
have minimal or no toxicity to humans
Therapeutic index
the ratio of the toxic dose (to the patient) to the therapeutic
dose (to eliminate the infection). The larger the index, the
safer is the drug (antibiotic) for human use.
Spektrum aktivitas
Limited number of microorganisms
Penicillin: gram (+)Narrow
spectrum
Broad range of microorganisms
Tetracycline: gram (-), gram (+), chlamydia, rickettsia
Broad spectrum
Table 20.2
Aktivitas antimikroba
Selective toxicity
A primary factor involved in the selective toxicity:
- LPS outer layer of gram (-) bacteria
- porin water-filled channels across this layer
Drug that pass through the porin channels must be relatively small and hydrophilic
Many antibiotic that are lipophilic or especially large do not enter gram (-) bacteria readily
Dinding sel gram negatif - Lipopolisakarida
Penggolongan antimikroba
berdasarkan efeknya thd mikroba
Lllmann, Color Atlas of Pharmacology
2000 Thieme
Bactericidal: penicillin,
cephalosporine
Bacteriostatic:
chloramphenicol,
sulphonamide,
tetracycline
Mekanisme kerja antimikroba
1. Inhibisi sintesis dinding sel
Inhibisi sintesis peptidoglikan ddg sel dinding sel rapuh lisis
Hanya dapat mempengaruhi sel-sel yang aktif bertumbuh
Selective
toxicity
Antibiotik bekerja
pada dinding sel
bakteri
Beta-lactams mechanism of actionhttp://www.microbelibrary.org/images/kaiser/penresanim.gif
Vancomycins mechanism of actionhttp://www.microbelibrary.org/images/kaiser/vanresanim.gif
2. Inhibisi sintesis proteinhttp://www.microbelibrary.org/images/kaiser/mechanisms/altribo_antibiot.html
Aktif pada ribosom 70S
Mempengaruhi 50 S ribosom:
- menghambat pembentukan ikatan peptida
(chloramphenicol)
- menghambat pergerakan ribosom sepanjang mRNA
(erythromycin)
Mempengaruhi 30 S ribosom:
- mengubah bentuk 30 S ribosom shg mRNA terbaca
salah (streptomycin, gentamicin)
- mengikat tempat perlekatan tRNA pada mRNA-
ribosom (tetracycline)
Sintesis Protein
3. Perusakan membran plasma
Perubahan permeabilitas membran sel hilangnya metabolit2 penting (sitoplasma keluar dari sel)
Polymixin B: berikatan dgn fosfolipid pada membran sel shg permeabilitas terganggu
Ketokonazole,amphotericin B
(Antifungi):
berikatan dgn sterol pada plasma
fungi shg terjadi kerusakan pada
membran plasma
4. Inhibisi sintesis asam nukleat
Mempengaruhi proses replikasi dan transkripsi DNA
Beberapa obat dpt mempengaruhi DNA dan RNA sel mamalia shg penggunaannya terbatas
Rifampicin, quinolones: selective toxicity
Rifampicin : bekerja pada RNA-polimerase inhibisi sintesis mRNA
Quinolones: inhibiting DNA gyrase enzyme (topoisomerase) inhibiting DNA synthesis.
Replikasi DNA
Supercoils DNA
5. Inhibisi sintesis metabolit2 penting
Inhibitor kompetitif
Co: gol. Sulfa dan trimetophrim
PABA (para amino benzoic acid) asam folat (coenzym untuk sintesis purin dan pirimidin)
Struktur sulfanilamide mirip dgn PABA
m.o + sulfanilamide asam folat tidak terbentuk
Selective toxicity
ANTIFUNGI
Antiviral
Antiprotozoa dan Antihelmintic
Mechanisms of resistance
1. Produce an enzyme that destroy or deactivates drug
enzim -lactamase
2. Slow or prevent the entry of the drug into the cell changes in the structure of the cytoplasmic
membrane
3. Alter the receptor for the drug
4. Alter the metabolic chemistry or abandon the
sensitive metabolic step altogether
5. Pump the drug out of the
cell before the drug can act
Antibiotics and methods of resistance
Chloramphenicol reduced uptake into cell
Tetracycline active efflux from the cell
-lactams, Erythromycin, Lincomycin
eliminates or reduces binding of
antibiotic to cell target
-lactams, Aminoglycosides, Chloramphenicol
enzymatic cleavage or modification
to inactivate antibiotic molecule
Sulfonamides, Trimethoprimmetabolic bypass of inhibited
reaction
Sulfonamides, Trimethoprimoverproduction of antibiotic target
(titration)
Inherent (Natural) resistance
Bacteria may be inherently resistant to an antibiotic.
The cell wall of gram negative bacteria is covered with an outer membrane that establishes a permeability barrier against the antibiotic.
Acquired resistance
Require either the modification of existing genetic material or the acquisition of new genetic material from another source PLASMID: R factors
2009 Kenneth Todar, PhD
Multiple resistance superbugs
resistant to 3 or more types of antimicrobial agents
Cross resistance
occurs when drugs are similar in structure
Synergism effect: sulfamethoxazole - trimetophrim
Antagonism effect: penicillin - tetracycline
UJI ANTIMIKROBA
The Diffusion Methods (cylinder
cup, paper
disc, well methods)
Kirby-Bauer test
Broth Dilution test
MIC and MBC test
E-test