AmbashRiaz AdeelaHussain SohailSamual ANTIMICROBIALS

Overview What are Antimicrobials? Classification of Antimicrobials What are Antibiotics? Classification of Antibiotics Example of Penicillin What are Antivirals? What are Antifungals? What are Ant parasites? Antimicrobial Therapy Antimicrobial Resistance Side Effects of Antimicrobials Modern research about Antimicrobials Case Study

Anti-microbial An anti-microbial is a substance that kills or inhibits the growth of microorganisms.  Bacteria  Fungi Protozoans

Anti-microbial Natural Fungi- Penicillin, Griseofulvin Bacteria- Polymixin, Bacitracin (Bacillus) - Tetracycline, Chloramphenicol streptomycin (Actinomycetes) Synthetic

Mode of Action Inhibit the cell wall synthesis Cause leakage from cell membrane Inhibit protein synthesis Cause misreading of mRNA code and affect permeability Interfere with DNA Interfere with metabolism

Classification Antibiotics Antifungals Antiviruls Antiprasitics

Antibiotics

Antibiotics Antibiotics are also known as antibacterials Antibiotics are medicinal products that have an anti-bacterial effect. Antibiotics are widely used in the prevention and treatment of infectious diseases. The most widely known antibiotic is perhaps penicillin

What are antibiotics for? An antibiotic is given for the treatment of an infection caused by bacteria. They are not effective against viruses. Important to know whether it is caused by bacteria or a virus

Classification of antibiotics The antibiotics are classified according to three criteria According to spectrum According to mode of action

According to spectrum The spectrum means the number of the organisms affected by the same drug There are two type of spectrum Narrow spectrum antibiotics Wide spectrum antibiotics

According to mode of action Bactericidal Bacteriostatic

Penicillin

History 1896- Ernest Duchesne- first discover penicillin 1928- Alexander Fleming- rediscover it accidentally  Howard Florey and Ernst Chain- isolated the bacteria-killing substance  1941- Charles Fletcher- first applied on a patient

Mechanism Structurally, penicillins are β-lactam antibiotics Which directly hit cell wall of bacteria

Mechanism Bacterial cell wall Bacterial cell walls are consisting of a protective peptidoglycan layer. peptidoglycan layer: N-acetylmuramic acid (NAM) N-acetylglucosamine (NAG) Two enzymes are involved: autolycine transpeptidase

Mechanism Autolysine: break the cross link of peptides Transpeptidase: cross link the peptidase Remodeling of cell wall maintain the rigidity of cell wall

Mechanism The penicillins act by inhibiting transpeptidase enzyme. This enzyme has a site to bind with penicillin – penicilline binding protein. Unable it to do its function Loss of integrity of bacterial cell wall Leak its celluler component Bacterial cell perish

Beta-lactam ring very unstable and therefore it participates Transpeptidase attacks the beta-lactam ring which opens up to give a more stable compound This compund remains bound to the transpeptidase via covalent linkage and thereby inhibits the enzyme by acylation of the active site.

Resistance to penicillin Mutations in the active site of the transpeptidase enzyme. use of newer penicillin antibiotics Many bacteriassysthesise an enzyme named Beta- Lactamase Video ……………….

Antivirals

Antivirals Antivirals are drugs that kill or prevent the growth of viruses  Viral infections are much harder to treat than bacterial infections Acyclovir is an antiviral drug that targets the herpes virus

Viral life cycle Attachment to a host cell. Release of viral genes and possibly enzymes into the host cell. Replication of viral components using host- cell machinery. Assembly of viral components into complete viral particles. Release of viral particles to infect new host cells.

Anti-viral targeting antiviral drug design is to identify viral proteins, or parts of proteins, that can be disabled targets should be unlike any proteins or parts of proteins in humans The targets should also be common across many strains of a virus, or even among different species of virus in the same family, so a single drug will have broad effectiveness

Key characteristics of Antivirals Able to enter the cell infected with virus Interfere with viral nucleic acid synthesis or regulation Some agents interfere with ability of virus to bind to cells Some agents stimulates the body’s immune system

Interferons Protein- made and released by host cells belong to the large class of glycoproteins known as cytokines

Functions activate immune cells natural killer cells macrophages increase recognition of infection or tumor cells increase the ability of uninfected host cells to resist new infection by virus

Mode of action An infected cell releases interferons the infected cell can warn neighboring cells of a viral presence by releasing interferon The neighboring cells, in response to interferon, produce large amounts of an enzymes Several different types of interferon are now approved for use in humans.

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