this slides includes overview of antimicrobial drugs, their classifications, antimicrobial resistance, adverse effects and toxicity, choice of antimicrobial drugs and its uses
this slides includes overview of antimicrobial drugs, their classifications, antimicrobial resistance, adverse effects and toxicity, choice of antimicrobial drugs and its uses
12 PRINCIPLES OF ANTIBIOTIC THERAPY seminar 12.pptxsneha
This PowerPoint presentation offers a concise yet technical overview of antibiotic therapy. Dive into antibiotic mechanisms, classifications, indications, and prudent use. Master essential aspects of antibiotic therapy for informed clinical decision-making.
Rational Use of Antibiotics. Infection was a major cause of morbidity and mortality, before the development of antibiotics.
The treatment of infections faced a great challenge during those periods.
Later in 1928, the discovery of Penicillin, a beta-lactam antibiotic, by Alexander Fleming opened up the golden era of antibiotics.
It marked a revolution in the treatment of infectious diseases and stimulated new efforts to synthesize newer antibiotics.
The period between the 1950s and 1970s is considered the golden era of discovery of novel antibiotic classes, with very few classes discovered since then.
263778731218 Abortion Clinic /Pills In Harare ,sisternakatoto
263778731218 Abortion Clinic /Pills In Harare ,ABORTION WOMEN’S CLINIC +27730423979 IN women clinic we believe that every woman should be able to make choices in her pregnancy. Our job is to provide compassionate care, safety,affordable and confidential services. That’s why we have won the trust from all generations of women all over the world. we use non surgical method(Abortion pills) to terminate…Dr.LISA +27730423979women Clinic is committed to providing the highest quality of obstetrical and gynecological care to women of all ages. Our dedicated staff aim to treat each patient and her health concerns with compassion and respect.Our dedicated group ABORTION WOMEN’S CLINIC +27730423979 IN women clinic we believe that every woman should be able to make choices in her pregnancy. Our job is to provide compassionate care, safety,affordable and confidential services. That’s why we have won the trust from all generations of women all over the world. we use non surgical method(Abortion pills) to terminate…Dr.LISA +27730423979women Clinic is committed to providing the highest quality of obstetrical and gynecological care to women of all ages. Our dedicated staff aim to treat each patient and her health concerns with compassion and respect.Our dedicated group of receptionists, nurses, and physicians have worked together as a teamof receptionists, nurses, and physicians have worked together as a team wwww.lisywomensclinic.co.za/
More Related Content
Similar to Classification & MOA of Antimicrobials.pdf
12 PRINCIPLES OF ANTIBIOTIC THERAPY seminar 12.pptxsneha
This PowerPoint presentation offers a concise yet technical overview of antibiotic therapy. Dive into antibiotic mechanisms, classifications, indications, and prudent use. Master essential aspects of antibiotic therapy for informed clinical decision-making.
Rational Use of Antibiotics. Infection was a major cause of morbidity and mortality, before the development of antibiotics.
The treatment of infections faced a great challenge during those periods.
Later in 1928, the discovery of Penicillin, a beta-lactam antibiotic, by Alexander Fleming opened up the golden era of antibiotics.
It marked a revolution in the treatment of infectious diseases and stimulated new efforts to synthesize newer antibiotics.
The period between the 1950s and 1970s is considered the golden era of discovery of novel antibiotic classes, with very few classes discovered since then.
263778731218 Abortion Clinic /Pills In Harare ,sisternakatoto
263778731218 Abortion Clinic /Pills In Harare ,ABORTION WOMEN’S CLINIC +27730423979 IN women clinic we believe that every woman should be able to make choices in her pregnancy. Our job is to provide compassionate care, safety,affordable and confidential services. That’s why we have won the trust from all generations of women all over the world. we use non surgical method(Abortion pills) to terminate…Dr.LISA +27730423979women Clinic is committed to providing the highest quality of obstetrical and gynecological care to women of all ages. Our dedicated staff aim to treat each patient and her health concerns with compassion and respect.Our dedicated group ABORTION WOMEN’S CLINIC +27730423979 IN women clinic we believe that every woman should be able to make choices in her pregnancy. Our job is to provide compassionate care, safety,affordable and confidential services. That’s why we have won the trust from all generations of women all over the world. we use non surgical method(Abortion pills) to terminate…Dr.LISA +27730423979women Clinic is committed to providing the highest quality of obstetrical and gynecological care to women of all ages. Our dedicated staff aim to treat each patient and her health concerns with compassion and respect.Our dedicated group of receptionists, nurses, and physicians have worked together as a teamof receptionists, nurses, and physicians have worked together as a team wwww.lisywomensclinic.co.za/
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
Title: Sense of Taste
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 structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
Basavarajeeyam is an important text for ayurvedic physician belonging to andhra pradehs. It is a popular compendium in various parts of our country as well as in andhra pradesh. The content of the text was presented in sanskrit and telugu language (Bilingual). One of the most famous book in ayurvedic pharmaceutics and therapeutics. This book contains 25 chapters called as prakaranas. Many rasaoushadis were explained, pioneer of dhatu druti, nadi pareeksha, mutra pareeksha etc. Belongs to the period of 15-16 century. New diseases like upadamsha, phiranga rogas are explained.
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
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
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
Follow us on: Pinterest
Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
2. 2
Chemotherapy/Anti-infectives
• Chemotherapy of TB, leprosy, enteric fever (Antibacterials)
• Chemotherapy of malaria, filaria, amoebiasis, Leishmaniasis
(Antiprotozoals)
• Antihelminthic drugs (worm and fluke infections)
• Antiviral drugs
• Antifungal drugs
• Anticancer drugs
• Antiseptics and disinfectants
3. 3
1. Classify antimicrobials using mode of action/
chemical class/ with examples.
2.Describe the mechanism of action of common
antimicrobial class.
TLOs
4. 4
• Chemotherapy: Treatment with specific drugs that selectively
suppress infecting microorganism/cancer cells without
significantly affecting the host (selective microbial toxicity).
• Antibiotics: Natural substances produced by microorganisms,
that selectively suppress growth/kill other microorganisms
• Antimicrobials: synthetic (manmade) antibacterial drugs and
not obtained from microorganisms.
• Antibacterial spectrum: Bacteria susceptible to antibacterial
actions of a particular drug.
• Broad spectrum: antibacterial effective against a wide variety of
both Gram+ve and Gram-ve pathogenic bacteria.
• Chemoprophylaxis: Use of antibiotics/antimicrobials to prevent
infection. Ex. before a surgical procedure or in patients with an
increased risk of infection.
Important Terms
5. 5
Classification of antimicrobials
1. Mechanism of Action
2. Type of organisms against which primarily active
3. Spectrum of activity
4. Type of action
5. Chemical structure
6. 6
1. Classification of antimicrobials based on mechanism of action
• Inhibit cell wall synthesis: Penicillins, Cephalosporins, Cycloserine,
Vancomycin.
• Leakage from cell membranes: Polymyxin, Amphotericin B, Nystatin.
• Inhibit protein synthesis: Tetracycline, Chloramphenicol,
Erythromycin, Clindamycin, Linezolid.
• Misreading of mRNA code and affect permeability: Strepto, Genta
• Inhibit DNA gyrase: Ciprofloxacin
• Interfere with DNA function: Rifampin, Metronidazole
• Interfere with DNA synthesis: Acyclovir, Zidovudine
• Interfere with intermediary metabolism: Sulphonamides, PAS,
Trimethoprim, Pyrimethamine, Ethambutol
7. 7
2. Classification of antimicrobials based on activity
on specific organism
• Antibacterials: Penicillins, Aminoglycosides, Erythromycin.
• Antifungal: Griseofulvin, Amphotericin B, Ketoconazole.
• Antiviral: Acyclovir, Amantadine, Zidovudine.
• Antiprotozoal: Chloroquine, Pyrimethamine, Metronidazole.
• Antihelminthic: Mebendazole, Pyrantel, Niclosamide.
8. 8
3. Classification of antimicrobials based on
spectrum of activity
• Narrow spectrum: Penicillin G, Streptomycin, Erythromycin
• Broad-spectrum: Tetracyclines, Chloramphenicol,
Fluoroquinolones,
12. 12
General Principles of Antimicrobial
chemotherapy
• Infections and its complications are the most
common type of condition seen in clinical practice
by general physicians.
• A decision to treat with antimicrobials , delay or not
to treat is taken based on patient presenting
condition.
• Hence patients treated/not to be treated with
antimicrobials/delayed use of antimicrobials
depends on the sound reasoning of physician.
13. 13
Selection of antimicrobial agent
I. Patient factors
II. Microorganism-related factors
III. Drug-related factors
I. Patient factors:
a. Age- age affects PK of many antimicrobials. Not all
antimicrobials can be prescribed to paediatric and
geriatric patients.
Ex. Conjugation and excretion of chloramphenicol is low in
newborn causing Gray baby syndrome in large doses.
AG have to be used with caution in elderly patients (↓GFR).
Sulfonamides may displace bilirubin from protein binding
sites and cause kernicterus in the neonates.
14. 14
b. Renal and hepatic function: Dose should be adjusted in
reduced organ function.
In mild renal failure, dose reduction is recommended for
aminoglycosides, and Vancomycin.
Reduce dose in moderate to severe failure. Ex. Metronidazole,
Fluoroquinolones, Clarithromycin.
Reduce dose in hepatic failure: metronidazole, and rifampin
Drugs to be avoided- Erythromycin, Pyrazinamide
c. Local factors:
1. Pus and secretions decrease efficacy during use of sulphonamides
and aminoglycosides.
2. Presence of necrotic material/foreign body makes eradication of
infection impossible.
3. Haematomas foster bacterial growth and drugs like TC, penicillins,
cephalosporins bind to degrade haemoglobin in the haematomas.
15. 15
d. Drug allergy: patient’s previous exposure to antimicrobial should
be obtained. Ex. Drug of choice for syphilis in a patient
allergic to penicillin is TC.
e. Impaired host defence: In a subject with normal host defence a
bacteriostatic antimicrobial may cure the condition. But in patients
with impaired immune systems, it is important to use intensive
therapy with cidal drugs.
f. Pregnancy: Antimicrobials to be avoided in pregnancy due to
risk to fetus. Ex. Tetracycline cause yellow atrophy of liver,
pancreatitis, and nephrotoxicity to mother.
Tooth and bone deformities to foetus.
Aminoglycosides cause fetal ototoxicity and nephrotoxicity.
g. Genetic factors: Primaquine, Pamaquine, Chloroquine,
Isoniazid, Sulfonamides, chloramphenicol, fluoroquinolones
and aspirin, cause hemolysis in G-6PD deficiency.
16. 16
II. Microorganism-related factors:
a. Clinical diagnosis directs choice of antimicrobials:
Usually the microorganism and its sensitivity to a
particular antimicrobial is always constant.
b. A good clinical judgement can be made: The
clinical features, type of microorganism,
sensitivity along with experience should help in
the selection of antimicrobial.
c. Bacteriological examination: If its difficult to
identify the microorganism or its sensitivity,
antimicrobial selected based on culture/sensitivity
testing. Empirical treatment with broad spectrum
antimicrobial can be started.
17. 17
III. Drug-related factors:
When antimicrobials are used to treat an infection preferred choice is
based on specific properties of drug:
(a) Spectrum of activity: a narrow-spectrum drug which
selectively kills organism preferred, due to high efficacy than
broad spectrum antimicrobial and do not disturb normal microbial
flora. Empirical treatment uses a broad spectrum drug that covers
all pathogens.
(b) Type of activity: infections in patients with normal immune
system respond well with cidal/static drugs.
bacteriCidal bacterioStatic
1. Acute infections respond well
with Cidal drugs.(↓ number of
bacteria at site of infection).
2. Cidal drug exhibit post-
antibiotic effect and no need to
maintain drug levels above MIC.
1.Takes time to resolve with static
drugs (prevents bacterial
multiplication).
2. Static drug level should be
maintained above MIC levels to
prevent bacterial multiplication and
chances of relapse.
18. 18
(c). Sensitivity of organism: depends on MIC and post antibiotic effect.
(d). Relative toxicity: A less toxic antimicrobial is preferred. (ex). A beta
lactam selected over an aminoglycoside.
(e). PK profile: antimicrobial activity depends on drug conc at site of
infection for adequate time period which depends on PK profile of drug.
1. Conc dependent inhibition: inhibitory effect depends on ratio of peak
conc to MIC. (Ex) amino glycosides and fluroquinolones. Single dose
has better effect.
2. Time-dependent inhibition: inhibitory effect depends on length of
time conc remains above MIC. Ex. Beta lactams, macrolides, etc.
Division of daily dose has better effect.
Drugs which penetrate better and attains high conc at site of infection
usually is highly efficacious. Ex fluoroquinolones. Penicillins and
aminoglycosides poor CSF penetration unless meninges inflammed.
19. 19
(f). Route of administration: for some antimicrobials like
aminoglycosides, penicillin G, carbenicillin, cephalosporins,
vancomycin it is usually preferable to give injection form. In serious
infections like meningitis, cellulitis, septicaemias parenteral
anitibiotic may be given. For less serious oral antibiotic given.
(g). Clinical efficacy: results of clinical trials also give an idea of efficacy
of antibiotic. Dosage regimens, duration of treatment info are also
available.
(h). Cost: Treatment depends on cost.
Antimicrobial Combinations: Objectives
1. To achieve synergism
2. To reduce severity of adverse effects
3. To prevent emergence of resistance
4. To broaden spectrum of antimicrobial action
20. 20
1. To achieve synergy (supra-additive): synergism
cause lowering of MIC. If MIC of each drug reduced to
25% or less then the pair considered synergistic.
Ex. Sulfamethoxazole+ trimethoprim (co-
trimoxazole) due to sequential block of folate
metabolism. Combination yields cidal whereas
individual drugs have static effect.
beta lactamase inhibitor clavulanic acid /sulbactam
+amoxicillin/ampicillin in H.inflenzae, N.gonorrheae
infections producing Beta lactamase enzymes.
penicillin/ampicillin+streptomycin/gentamycin or
vancomycin+gentamycin for enterococcal,
subacute bacterial endocarditis. Combo of
bactericidal drugs produce faster cure and reduces
chances of relapse.
21. 21
Failure of antimicrobial therapy
Success of antimicrobial therapy measured by clinical improvement /
eradication of infecting organism.
Causes of failure:
1. Improper selection of drug, dose, route of administration,
duration of treatment.
2. Treatment started too late.
3. Failure to take necessary adjuvant measures. Ex. Drainage of
abscesses, empyema, removal of stones, foreign bodies,
infected gall bladder, adjustment of urinary pH in UTI,
control of diabetes etc.
4. Poor host defence- Immuno compromised states like
leukaemias, neutropenia, HIV and TB.
5. Infecting organism present behind barriers such as behind
heart valves (SABE), inside eye ball, brain etc.
6. Presence of dormant/altered organisms giving rise to
relapses.
23. 23
1. Inhibit cell wall synthesis (CWSI): Beta lactams (Penicillins,
Cephalosporins) Vancomycin.
2. Inhibit protein synthesis (PSI): Tetracycline, Chloramphenicol,
Erythromycin, Clindamycin, Linezolid.
Misreading of mRNA code and affect permeability: Strepto, Genta.
3. Inhibit DNA gyrase: Ciprofloxacin
4. Interfere with intermediary metabolism: Sulphonamides, PAS,
Trimethoprim, Pyrimethamine, Ethambutol
Classification of antimicrobials based on mechanism of action
24. 1.CWSI
Beta-lactam inhibit cell wall synthesis by:
(1) binding of the drug to specific enzymes (penicillin-
binding proteins[PBPs]) located in the bacterial
cytoplasmic membrane.
(2) inhibition of the transpeptidation reaction that cross-
links the linear peptidoglycan chain constituents of the cell
wall.
(3) activation of autolytic enzymes that cause lesions in
the bacterial cell wall cause bactericidal effects.
24
27. Drugs Mechanism of action
Tetracycline (BS) Binds reversibly to the 30S subunit of the bacterial
ribosome, blocking access of the amino acyl-tRNA to the
mRNA-ribosome complex at the acceptor site.
Aminoglycosides
(BCD)
Bind to the 30S ribosomal subunit and interfere with
protein synthesis in at least 3 ways: (1) block formation of
the initiation complex; (2) cause misreading of the code
on the mRNA template; and (3) inhibit translocation.
Chloramphenicol
(BS)
Binds to the bacterial 50S ribosomal subunit and inhibits
protein synthesis at the peptidyl transferase reaction
Macrolides (BS) Bind irreversibly to a site on the 50S subunit of the
bacterial ribosome, thus inhibiting the translocation steps
of protein synthesis.
Clindamycin (BS) Same as macrolides.
Linezolid (BS) Binds to a site on the bacterial 23S ribosomal RNA of the
50S subunit and prevents the formation of a functional
70S initiation complex. 27
28. 3. Inhibitors of DNA gyrase
MOA: Fluoroquinolones (Ciprofloxacin) interfere with bacterial
DNA synthesis by inhibiting topoisomerase II (DNA gyrase) in
gram-negative organisms, and topoisomerase IV, in gram-
positive organisms.
Block the relaxation of supercoiled DNA catalyzed by
topoisomerase II (DNA gyrase), required for normal
transcription and duplication.
Inhibition of topoisomerase IV by fluoroquinolones
interferes with the separation of replicated chromosomal
DNA during cell division leading to BCD effects.
28
29. 4. Interfere with intermediary metabolism
Enzymes requiring folate-derived cofactors are essential for
the synthesis of purines and pyrimidines (precursors of
RNA and DNA) and other compounds necessary for
cellular growth and replication.
In the absence of folate, cells cannot grow or divide. To
synthesize the critical folate derivative, tetrahydrofolic acid,
humans must obtain preformed folate in the form of folic
acid as a vitamin from the diet.
In contrast, bacteria must synthesize folate de novo.
29
30. Sulfonamides (sulfa drugs) are antimicrobials that inhibit
this de novo synthesis of folate.
Trimethoprim prevents microorganisms from converting
dihydrofolic acid to tetrahydrofolic acid, with minimal effect
on a human cell's ability to make this conversion.
Thus, both sulphonamides (sulphamethoxazole) and
trimethoprim (COMBO COTRIMOXAZOLE IS
SYNERGISTIC COMBO; BCD) interfere with the ability of
an infecting bacterium to divide.
30