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Presented by:
Sheetal Singh
M.sc(Bio-Chem) III Sem
Suresh Gyan Vihar University, Jaipur
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INTRODUCTION
CHARACTERISTICS
ANTIBIOTICS RESISTANCE
CLASSIFICATION
ANTIFUNGAL DRUGS
ANTI VIRAL DRUGS
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A substance of low molecular
weight produced by micro-
organism as secondary metabolites
that inhibit or stop the growth ofother micro-organism in vitro and
in vivo selectively, when it is used
in low concentration.
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It must be able to
reach the part of the
human body where the
infection is occurring. It should not cause the
development of
resistant forms of
parasites
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It should not produce
undesirable side effects
in the host such as
allergic reaction, nerve
damage or irritation of
the kidneys and
gastrointestinal tract.
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It should be given
orally without
inactivation by
stomach acid, or byinjection (parenterally)
without binding to the
blood proteins.
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Finally, it should have ahigh level of solubility inthe body fluids and be
possible to achieveconcentrations in thetissue or blood, which aresufficiently high to inhibitor kill the infectious
agent.
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Bacteria either have pre- existing resistance to drugs or developresistance. The internal or acquired resistant are identical andcan be explained by following reasons
1) Inactivation or modification of drug by bacterial enzyme.
2) Formation of impermeable barrier so that drug can not reach thedesired region of action.
3) Changing the target itself so drug cant bind or have an effect onit.
4) DNA transfer of drug resistance from one organism to other by
transformation ,transduction or bacterial conjugation.5) Development of altered metabolic pathway which commit the
effect of the drug to be bypassed.
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Antimicrobials are classified in several ways.
1. On basis of spectrum of study.
2. On basis of effect on bacteria.3. On basis of mode of action
a) Cell wall synthesis inhibitor
b)
Protein synthesis inhibitorc) Nucleic acid inhibitor
d) Other metabolic functions inhibitor
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Depending on the range ofbacterial species susceptibleto these agents,
antibacterials are classifiedas :
1. Broad-spectrum
2. Narrow- Spectrum
3. Extended -spectrum
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Because of differences in themechanisms by whichantibiotics affect bacteria, the
clinical use of antibacterialsmay have very differenteffects on bacterial agents,leading to an endpoint ofeither inactivation or actualdeath of the bacteria.
Bactericidal drugs
Bacteriostatic drugs
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Differentantibiotics havedifferent modes ofaction, owing to
the nature of theirstructure anddegree of affinityto certain target
sites within
bacterial cells.
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-lactam inhibitors other antibiotics
penicillin cephalosporins
carbapenem monobactams
Bacitracin Vancomycin
Penicillin G
Penicillin V
Oxacillin
Cloxacillin
Dicloxacillin
PARENETRAL
Imipenem
Meropenem
Aztreonam
Cefazolin
Cefmetazole
Ceftizoxime
Cefepime
ORAL
CefadroxilCefaclor
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Antimicrobial drug selectively interfere withsynthesis of the bacterial cell wall.
The cell wall is made by polymer calledpeptidoglycan that consist of a glycan unit joined toeach other by peptide cross links.
Synthesis occurs in three steps:
1) Occurs in cytoplasm.
2)
Inner surface of cytoplasmic membrane.3) Occurs in peri-plasmic space(in gram negative
bacteria).
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Protein synthesis is an essential process necessary formultiplication and survival of all bacterial cells.
Several types of antibacterial agent s target bacterialprotein synthesis by binding either to 30S or 50S
subunits of intracellular ribosomes.
The result is disruption of normal cellularmetabolism of bacteria and leads to death orinhibition of its growth .EXAMPLES-
Aminoglycosides, chloramphenicol, tetracyclines,macrolides, etc.
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Some chemotherapeutic agents affect the synthesis
of DNA or RNA or can bind to them so that
message can not be read and they can block the
growth of cell.
FLUOROQUINOLONES INHIBITORS OF FOLATE
SYNTHESIS
1stgeneration
2nd
generation
3rd
generation
4th
generation
Mefinide
Nalidixicacid
Ciprofloxacin
Gatifloxacin
trovafloxacin
Sulfadiazine, Silver Sulfadiazine,Sulfamethoxazolenorfloxac
inlavofloxacin
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Quinolones inhibit DNA gyrase
(also called as topoisomerase)
This enzyme introduces
negative superhelical turns into
duplex DNA using the energy of
ATP.
Fluoroquinolones enters the
bacterium and inhibiyt
replication of bacterial DNA by
interfering with action of DNA
gyrase .
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Some antibiotics act on
selected cellular processes
that are essential for
survival of bacterial
pathogen. SULFONAMIDES and
TIRIMETHOPRIM
disrupts folic acid
pathway , which isessential step for bacteria
to produce precusors
important for DNA
synthesis.
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An antifungal agent is a drug that selectively eliminates
fungal pathogens from a host with minimal toxicity to the
host.
Infectious disease caused by fungi is called MYCOSIS.
CLASSIFICATION
Drugs for systemicmycosis
Drugs for sub-cutaneousmycosis
Amphotericin B Econazol
Flucytosine Griseofluvin
Fluconazole Nystatin
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Different classes of drugtarget plasma membrane,sterol biosynthesis , DNAbiosynthesis and -glucanbiosynthesis.
Fungal membranes andsterol biosyntheticenzymes are differentenough from ours that
these agents kill fungi andnot us.
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Virus are intracellular parasites that lack independentmetabolism and can replicate only within living hostcell.
Amantadine and - globulininhibit penetration of cell
by virus. Acycloviris very selective as it remain inactive until
phosphorylated by enzymes that are synthesized byvirus.
Antiretroviral drugs suppress the replication of HIV . Protease inhibitors ,in HIV m-RNA are translated into
inert proteins.
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Dixon B .2006 . Sullfas true
significance. Microle 1(11):500-501
Pharmacological module
Microbiology Michael J Pelczar
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