This document discusses the mechanisms of action of antimicrobial agents. It begins with a brief history of antimicrobial use from ancient times to the modern era. It then covers classifications of antimicrobials and their main mechanisms, which include inhibiting cell wall synthesis, cytoplasmic membrane function, nucleic acid synthesis, and ribosome function. Specific drug classes are discussed for each mechanism, such as penicillins, cephalosporins, and glycopeptides for cell wall inhibitors. The document concludes that understanding antimicrobial mechanisms of action is important for optimal patient care and preventing resistance.
The slides explain introduction of antimicrobial chemotherapy and history of chemotherapy. Presented at institute of Biochemistry and Biotechnology, University of Punjab.
Mechanism of action of major antibiotic classes including betal lactam agents, aminoglycosides, macrolides, tetracyclines, quinolons, vancomycin, oxazolidionons. Detailed review and illustrations
Hello friends. In this PPT I am talking about Anti-viral drugs drugs. If you like it, please do let me know in the comments section. A single word of appreciation from you will encourage me to make more of such videos. Thanks. Enjoy and welcome to the beautiful world of pharmacology where pharmacology comes to life. This video is intended for MBBS, BDS, paramedical and any person who wishes to have a basic understanding of the subject in the simplest way.
The slides explain introduction of antimicrobial chemotherapy and history of chemotherapy. Presented at institute of Biochemistry and Biotechnology, University of Punjab.
Mechanism of action of major antibiotic classes including betal lactam agents, aminoglycosides, macrolides, tetracyclines, quinolons, vancomycin, oxazolidionons. Detailed review and illustrations
Hello friends. In this PPT I am talking about Anti-viral drugs drugs. If you like it, please do let me know in the comments section. A single word of appreciation from you will encourage me to make more of such videos. Thanks. Enjoy and welcome to the beautiful world of pharmacology where pharmacology comes to life. This video is intended for MBBS, BDS, paramedical and any person who wishes to have a basic understanding of the subject in the simplest way.
Anti mycobacterial drugs (tuberculosis drugs)Ravish Yadav
The all the content in this profile is completed by the teachers, students as well as other health care peoples.
thank you, all the respected peoples, for giving the information to complete this presentation.
this information is free to use by anyone.
Bacteria have their own enzymes for
1. Cell wall formation
2. Protein synthesis
3. DNA replication
4. RNA synthesis
5. Synthesis of essential metabolites
• LEARNING OBJECTIVES
After completing this chapter, reader should be able to:
To kuow about product line and product mix decision.e kslyog
To study about product ife cycle.
To kuow about branding, packeging and labelling decisions ef product.
How to manage product in pharmaceutical industry.
To study product portfolio analysis.
2.1 INTRODUCTION
In present scenario, marketing has become an indispensable activity for an organization.
To create an edge over competitors, it's necessary to use marketing as a tool. Any marketing
activity starts with one question, what are we going to sell. Answer of this question would be
product, service or any idea that marketer wants to sel.
A company or firm always works on idea of providing solution to a particular problem. For
example, suppose a student wants to go for higher studies in abroad but dont know how to
apply for higher education in foreign country, then solution of this problem can be services
of consultancy firms. In this case, organization is not selling any real commodity but
providing intangible services. Product is a wider term and it can be anything-tangible,
intangible, durable, and non-durable. Like television, insurance, egg, flour, so many products
are marketed by the marketers. Product is something that has the capacity to satisfy any
unsatisfied need.
stoe hich nroMide
A company or firm always works on idea of providing solution to a particular problem. For
example, suppose a student wants to go for higher studies in abroad but don't know how to
apply for higher education in foreign country, then solution of this problem can be services
of consultancy firms. In this case, organization is not selling any real commodity but
providing intangible services. Product is a wider term and it can be anything-tangible,
intangible, durable, and non-durable. Like television, insurance, egg, flour, so many products
are marketed by the marketers. Product is something that has the capacity to satisfy any
unsatisfied need.
A product is a collection of service, physical and symbolic attributes which provide
benefits or pleasure to a buyer or user. Customer prefers physical property as shape and size
of the product.
2.2 CLASSIFICATION
Product classification on basis of potential in global market:
P
) Local products: It is appropriate in one single market.s ixs 2oit: Sst
() Intermational products: It has additional potential into other markets.2i2 A
t
(ii) Multinational products: Have unique characteristics of national markets.
(iv) Global products: Designed according to global segments.
Product is the key element of product-mix. It can be any service, object, commodity.
event etc The main purpose of the product is to satisfy consumer and fulfil their needs.
According to Philip Kotler, "Product is anything that can be offered to a market for
alteration, use or consumption that might satisfy a need or want It includes physical objects.
services, persons, place, organizations or ideas".
Product Layers
A produ
MANAGEMENT OF ATRIOVENTRICULAR CONDUCTION BLOCK.pdfJim Jacob Roy
Cardiac conduction defects can occur due to various causes.
Atrioventricular conduction blocks ( AV blocks ) are classified into 3 types.
This document describes the acute management of AV block.
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
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Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
3. HISTORY
• Antimicrobial agents are substances that
are used to inhibit or kill the growth of
microorganisms(bacteria,viruses,fungi and
protozoa)
• The earliest evidence of successful
chemotherapy is from ancient Peru, where
the Indians used bark from the cinchona
tree to treat malaria.
• Other substances were used in ancient
China
4. HISTORY-2
17th Century:
Treatment of infectious diseases, e.g.
• quinine for malaria;
• emetine for amoebiasis.
5. HISTORY-3
20th century:
• Modern chemotherapy has been dated to the work of
Paul Ehrlich in Germany,
• Paul Ehrlich formulated the principle of selective toxicity.
• The first planned chemotherapy was arsphenamines for
syphilis.
1935:
• The beginning of Current era of chemotherapy with
discovery of the sulfonamides.
1940:
• Penicillin that was discovered in 1929, was demonstrated to
be effective
Subsequent 25 years after:
• Development of streptomycin, tetracycline,
chloramphenicol and others.
7. Classification of antimicrobial
agents
• According to whether they are bactericidal
or bacteriostatic
• By target site
• By chemical structure
8. ANTIMICROBIAL AGENTS
Selective toxicity
• Exhibited by an ideal antimicrobial agent.
• Drug is harmful to the parasite but not to the
host.
• relative rather than absolute, i.e. drug in
concentration tolerated by the host may
damage an infecting microorganism.
• due to a function of drug specific receptor or
inhibition of biochemical events essential to the
organism.
9. Biochemical Basis of Antimicrobial
Action
• Bacterial cells grow and divide, replicating
repeatedly to reach the large numbers present
during an infection or on the surfaces of the
body.
• To grow and divide, organisms must synthesize
or take up many types of biomolecules.
• Antimicrobial agents interfere with specific
processes that are essential for growth and/or
division .
10. Biochemical Basis of
Antimicrobial Action -3
Antibiotic agents may be either:
• bactericidal:- killing the target bacterium
• Bacteriostatic:- inhibiting its growth.
Bactericidal agents are more effective, but
bacteriostatic agents can be extremely
beneficial since they permit the normal
defenses of the host to destroy the
microorganisms.
11. MECHANISMS OF ACTION OF
ANTIMICROBIAL AGENTS
They are classified as follows:
• inhibitors of bacterial cell walls,
• inhibitors of cytoplasmic membranes,
• inhibitors of nucleic acid synthesis, and
• inhibitors of ribosome function .
• Inhibitors of folate pathway
12.
13. Inhibition of cell wall synthesis
(Bacitracin, Cephalosporins, Cycloserine,
Penicillins, Vancomycin)
• Bacteria are classified as Gram-positive and
Gram-negative organisms on the basis of
staining characteristics.
• Gram-positive bacterial cell walls contain
peptidoglycan and teichoic or teichuronic
acid, and the bacterium may or may not be
surrounded by a protein or polysaccharide
envelope.
• Gram-negative bacterial cell walls contain
peptidoglycan, lipopolysaccharide,
lipoprotein, phospholipid, and protein .
14.
15. Inhibition of cell wall synthesis-2
• The critical attack site of anti-cell-wall
agents is the peptidoglycan layer.
• This layer is essential for the survival of
bacteria in hypotonic environments;
• loss or damage of this layer destroys the
rigidity of the bacterial cell wall, resulting in
death.
16. Inhibition of cell wall synthesis-3
• The rigid cell wall possessed by most
bacteria is lacking in the host cells. This is
prime target for agent that exhibit selective
toxicity.
• Inhibitors of bacterial cell wall synthesis act
on the formation of peptidoglycan layer.
• Bacteria that lack peptidoglycan, such as
mycoplasmas, are resistant to these agents.
17. Inhibition of cell wall synthesis-5
• Penicillins and cephalosporins/cephamycins
are widely used to inhibit both Gram-positive
and Gram-negative bacilli.
• Monobactams inhibit only aerobic Gram-
negative bacilli,
• Clavulanic acid acts as a ß-lactamase inhibitor,
and thienamycin inhibits a wide range of
aerobic and anaerobic species.
18. Inhibition of cell wall synthesis-6
• Vancomycin interrupts cell wall synthesis by forming
a complex with the C-terminal D-alanine residues of
peptidoglycan precursors.
• Complex formation at the outer surface of the
cytoplasmic membrane prevents the transfer of the
precursors from a lipid carrier to the growing
peptidoglycan wall by transglycosidases.
• Biochemical reactions in the cell wall catalyzed by
transpeptidases and D,D-carboxypeptidases are
also inhibited by vancomycin and other
glycopeptide antimicrobials.
• Because of its large size and complex structure,
vancomycin does not penetrate the outer
membrane of gram-negative organisms.
20. Bacterial Cytoplasmic Membranes
• Biologic membranes are composed
basically of lipid, protein, and lipoprotein.
• The cytoplasmic membrane acts as a
diffusion barrier for water, ions, nutrients,
and transport systems.
• Most workers now believe that
membranes are a lipid matrix with globular
proteins randomly distributed to penetrate
through the lipid bilayer.
21. Bacterial Cytoplasmic Membranes-2
• A number of antimicrobial agents can cause
disorganization of the membrane. These
agents can be divided into cationic, anionic,
and neutral agents.
• The best-known compounds are polymyxin B
and colistemethate (polymyxin E).
• These high-molecular-weight octapeptides
inhibit Gram-negative bacteria that have
negatively charged lipids at the surface.
22. Bacterial Cytoplasmic Membranes-3
• Since the activity of the polymyxins is
antagonized by Mg2+ and Ca2+, they probably
competitively displace Mg2+ or Ca2+ from the
negatively charged phosphate groups on
membrane lipids.
• Basically, polymyxins disorganize membrane
permeability so that nucleic acids and cations
leak out and the cell dies.
• The polymyxins are of virtually no use as
systemic agents since they bind to various
ligands in body tissues and are potent toxins
for the kidney and nervous system.
24. Antimicrobial agents can interfere with
nucleic acid synthesis at several
different levels.
• inhibit nucleotide synthesis or interconversion;
• prevent DNA from functioning as a proper
template; and
• interfere with the polymerases involved in the
replication and transcription of DNA.
25. Inhibition of DNA-Directed RNA
Polymerase
• Rifamycins are a class of antibiotics that inhibit DNA-
directed RNA polymerase.
• Polypeptide chains in RNA polymerase attach to a
factor that confers specificity for the recognition of
promoter sites that initiate transcription of the DNA.
• Rifampin binds noncovalently but strongly to a
subunit of RNA polymerase and interferes
specifically with the initiation process.
• However, it has no effect once polymerization has
begun.
26. Inhibition of DNA Replication
• DNA gyrase and topoisomerase I act in concert
to maintain an optimum supercoiling state of
DNA in the cell. In this capacity,
• DNA gyrase is essential for relieving torsional
strain during replication of circular
chromosomes in bacteria.
• The enzyme is a tetrameric protein composed
of two A and two B subunits. A transient,
covalent bond between the A subunit and DNA
occurs during the double strand passage
reaction catalyzed by gyrase.
27. Inhibition of DNA Replication-2
• Quinolones such as nalidixic acid, bind to the
cleavage complex composed of DNA and gyrase
during this strand passage.
• This interaction of quinolone acts to stabilize the
cleavage intermediate which has a detrimental effect
on the normal DNA replication process.
• The effects of this inhibition result in the death of the
bacterial cell.
• The newer fluoroquinolones such as ciprofloxacin,
norfloxacin, and ofloxacin also interact with DNA
gyrase and possess a broad spectrum of
antimicrobial activity.
28. Inhibition of DNA Replication-3
• Nalidixic inhibits only aerobic Gram-negative
species.
• In ciprofloxicin, the flourine provides Gram-
positive activity, the piperazine group increases
activity against members of the
Enterobacteriaceae, and the piperazine and
cylopropyl groups give activity against
Pseudomonas species.
29. Inhibition of DNA Replication-4
• Nitroimidazoles such as metronidazole inhibit
anaerobic bacteria and protozoa. The nitro
group of the nitrosohydroxyl amino moiety is
reduced by an electron transport protein in
anaerobic bacteria. The reduced drug causes
strand breaks in the DNA. Mammalian cells are
unharmed because they lack enzymes to
reduce the nitro group of these agents.
• Metronidazole enters an aerobic bacterium via
the electron transport protein ferrodoxin,where
it is reduced. The drug then binds to DNA, and
DNA breakage occurs.
30. Antimicrobial Inhibitors of
Ribosome Function.
• Bacterial ribosomes contain two subunits,
the 50S and 30S subunits.
• Anti-ribosomal antibiotics impair ribosomes
by binding to either 50S or 30S ribosomal
subunits
• Ribosomes are essential for translation of
mRNA into proteins
• No translation N No protein synthesis
• No protein synthesis N No growth
31.
32. Ribosome Home Plate
• Baseball player slides
into home
• The ball is fielded by the
catcher who makes a
CLEan TAG
• The word CLEean lies
over the base: these
inhibit i 50S
• The word TAG lies
beneath the base: these
inhibit 30S
33. Antimicrobial Inhibitors of
Ribosome Function-2
• Aminoglycosides act by binding to specific
ribosomal subunits.
• Aminoglycosides are complex sugars
connected in glycosidic linkage .
• They differ both in the molecular nucleus, which
can be streptidine or 2-deoxystreptidine, and in
the aminohexoses linked to the nucleus.
• Essential to the activity of these agents are free
NH, and OH groups by which aminoglycosides
bind to specific ribosomal proteins.
34. Antimicrobial Inhibitors of
Ribosome Function-3
• Streptomycin was the first aminoglycoside
studied
• It is rarely used clinically today except to treat
tuberculosis.
• Its mode of action differs to some extent from
that of the other clinically useful
aminoglycosides, which are 2-deoxystreptidine
derivatives such as gentamicin, tobramycin,
and amikacin.
• Streptomycin binds to a specific S12 protein in
the 30S ribosomal subunit and causes the
ribosome to misread the genetic code.
35. Antimicrobial Inhibitors of
Ribosome Function-4
• Other aminoglycosides bind not only to the
S12 protein of the 30S ribosome, but also to
some extent to the L6 protein of the 50S
ribosome.
• This latter binding is quite important in terms
of the resistance of bacteria to
aminoglycosides.
• Indeed, the aminoglycoside-type drugs can
combine with other binding sites on 30S
ribosomes, and they kill bacteria by inducing
the formation of aberrant, nonfunctional
complexes as well as by causing misreading.
36. Antimicrobial Inhibitors of
Ribosome Function-5
• Other agents that bind to 30S ribosomes
are the tetracyclines.
• These agents appear to inhibit the binding
of aminoacyl-tRNA into the A site of the
bacterial ribosome.
• Tetracycline binding is transient, so these
agents are bacteriostatic.
• Nonetheless, they inhibit a wide variety of
bacteria, chlamydias, and mycoplasmas
and are extremely useful antibiotics.
37. Antimicrobial Inhibitors of
Ribosome Function-6
• Spectinomycin is an aminocylitol antibiotic that
is closely related to the aminoglycosides. It
binds to a different protein in the ribosome and
is bacteriostatic but not bactericidal. It is used
to treat penicillin-resistant gonorrhea.
38. Antimicrobial Inhibitors of
Ribosome Function-7
• There are three important classes of drugs that
inhibit the 50S ribosomal subunit.
• Chloramphenicol is a bacteriostatic agent that
inhibits both Gram-positive and Gram-negative
bacteria. It inhibits peptide bond formation by binding
to a peptidyltransferase enzyme on the 50S
ribosome.
• Macrolides are large lactone ring compounds that
bind to 50S ribosomes and appear to impair a
peptidyltransferase reaction or translocation, or both.
• The most important macrolide is erythromycin, which
inhibits Gram-positive species and a few Gram-
negative species such as Haemophilus,
Mycoplasma, Chlamydia, and Legionella.
39. Antimicrobial Inhibitors of
Ribosome Function-8
• New molecules such as azithromycin and
clarithromycin have greater activity than
erythromycin against many of these pathogens.
• Lincosamides, of which the most important is
clindamycin, have a similar site of activity
• Both macrolides and lincosamides are
generally bacteriostatic. inhibiting only the
formation of new peptide chains.
40. Inhibitors of folate pathway
• Sulfonamides competitively block the
conversion of pteridine and p-aminobenzoic
acid (PABA) to dihydrofolic acid by the
enzyme pteridine synthetase.
• Sulfonamides have a greater affinity than p-
aminobenzoic acid for pteridine synthetase.
• Trimethoprim has a tremendous affinity for
bacterial dihydrofolate reductase (10,000 to
100,000 times higher than for the mammalian
enzyme); when bound to this enzyme, it
inhibits the synthesis of tetrahydrofolate.
41.
42. Antibacterial Agents that Affect
Mycobacteria
Isoniazid
• is a nicotinamide derivative that inhibits mycobacteria.
• precise mode of action is not known, but it affects the
synthesis of lipids, nucleic acids, and the mycolic acid of the
cell walls of these species.
Ethambutol
• mechanism of action is unknown.
• mycostatic, whereas isoniazid is mycocidal.
Rifampin and streptomycin,
• affect mycobacteria in the same manner that they inhibit
bacteria.
Pyrazinamide
• a synthetic analog of nicotinamide. It is bactericidal, but its
exact mechanism is unknown
43. Conclusion
• Adequate knowledge of various
antimicrobial classification,mechanisms of
action are crucial in optimal patients care
and in prevention of resistance.