The presentation gives detailed account on various methods for Control of growth of Micro-organisms. Physical, chemical methods to control growth of micro-organisms. Evaluation of Disinfectant is also explained.
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
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
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.
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
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
- 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
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
Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
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.
1. Ms. Renu NK Jaisinghani
Assistant Professor
Department of Microbiology
Smt. Chandibai Himathmal Mansukhani College
Mumbai
Control of
Microorganisms
2. Methods of Sterilization
Physical methods:
Heat ( dry heat & moist heat)
U.V. Light
Ionizing Radiation
Filtration
Chemical method: (used for heat sensitive equipments)
Ethylene Oxide
Gluteraldehyde
Phenolics
3. Dry Heat( HOT AIR OVEN)
Kills microorganisms by destroying their oxidative processes.
Has electric element in chamber as source of heat plus a fan to circulate air for even
distribution of heat in chamber. Oven without fan is dangerous. Used for items that are
lacking water such as:
-Metals
-Glassware
-Ointment / Oils/ Waxes /Powder
4. Time Temperature regime for sterilization
Dry Heat( HOT AIR OVEN)
TEMPERATURE
O
C
TIME
140 1.5h
160 1h
180 0.5h
6. Wet Heat (AUTOCLAVING)
Its works under the principle steam under pressure.
Moist heat kills microorganisms by denaturating proteins.
Time and temperature regime 1210
C at 15psi for 20mins
The autoclave is a tough double walled chamber in which air is replaced by pure
saturated steam under pressure.
9. Fractional Sterilization(Tyndallization)
This method involves heating the material at 1oo°C on three successive
days with incubation periods in between. Resistant spores germinate
during the incubation periods; on subsequent exposure to heat, the
vegetative cells will be destroyed.
If spores are present and do not germinate during the incubation periods,
the material will not be sterilized.
Apparatus known as the Steam Arnold is used for this technique;
11. Pasteurization
Milk, cream, and certain alcoholic beverages (beer and wine)
are subjected to a controlled heat treatment (called
pasteurization) which kills microorganisms of certain types but
does not destroy all organisms.
12. Definition:
Heating of foods at temperature of 630
C for 30mins, so
that the spoilage causing bacteria are killed, without
affecting the nutritive properties of the food.
Pasteurization
16. Ionizing radiation
Ionizing radiation is radiation with enough energy so that during an interaction
with an atom, it can remove tightly bound electrons from the orbit of an atom,
causing the atom to become charged or ionized.
Gamma rays and x-rays, which have energies of more than about 10 eV, are
called ionizing radiations because they have enough energy to knock electrons
away from molecules and ionize them.
Mode of Action:
When such radiations pass through cells, they create free hydroxyl radicals, and
some peroxides, which in turn can cause different kinds of intracellular damage.
Moreover, since this damage is produced in a variety of materials, ionizing
radiations are rather nonspecific in their effects.
17. Non-Ionizing Radiation
The ultraviolet portion of the spectrum includes all radiations
from 150 to 3900 A.
Germicidal lamps, which emit ultraviolet radiations, are widely
used to reduce microbial populations. For example, they are
used extensively in hospital operating rooms, in aseptic filling
rooms, in the pharmaceutical industry, where sterile products
are being dispensed into vials or ampules, and in the food and
dairy industries for treatment of contaminated surfaces.
18. Mode of Action: Ultraviolet light is absorbed by many cellular
materials but most significantly by the nucleic acids, where it
does the most damage. The absorption and subsequent reactions
are predominantly in the pyrimidines of the nucleic acid. One
important alteration is the formation of a pyrimidine dimer in
which two adjacent pyrimidines become bonded. Unless dimers
are removed by specific intracellular enzymes, DNA replication
can be inhibited and mutations can result.
Non-Ionizing Radiation
19. Low Temperature
Temperatures below the optimum for growth depress the rate of metabolism,
and if the temperature is sufficiently low, growth and metabolism cease.
Low temperatures are useful for preservation of cultures, since
microorganisms have a unique capacity for surviving extreme cold.
Agar-slant cultures of some bacteria, yeasts, and molds are customarily
stored for long periods of time at refrigeration temperatures of about 4 to 7°
C. Many bacteria and viruses can be maintained in a deep-freeze unit at
temperatures from —20 to - 70°C.
20. Liquid nitrogen, at a temperature of -196°C is used for preserving
cultures of many viruses and microorganisms, as well as stocks of
mammalian tissue cells used in animal virology and many other types of
research.
In all these procedures, the initial freezing kills a fraction of the
population, but the survivors may remain viable for long periods. From
these facts it is immediately apparent that low temperatures, however
extreme, cannot be depended upon for disinfection or sterilization.
Microorganisms maintained at freezing or subfreezing temperatures may
be considered dormant;
Low Temperature
21. they perform no detectable metabolic activity. This static condition is the
basis of successful application of low temperatures for the preservation
of Foods. Thus from a practical standpoint, high temperatures may be
considered as Microbicidal and low temperatures (freezing or lower) as
Microbistatic.
Low Temperature
22. Desiccation
Desiccation:
The process by which a substance is dried out and the moisture removed.
Desiccation of the microbial cell causes a cessation of metabolic activity, followed by a
decline in the total viable population. In general, the time of survival of
microorganisms after desiccation varies, depending on the following factors:
1The kind of microorganism
2 The material in or on which the organisms are dried
3 The completeness of the drying process
4 The physical conditions to which the dried organisms are exposed, e.g., light,
temperature, and humidity
23. Desiccation
The tubercle bacillus (Mycobacterium tuberculosis) dried in sputum remains viable
for even longer periods of time. Dried spores of microorganisms are known to remain
viable indefinitely.
24. Osmotic pressure
Osmotic pressure: The pressure built up within the cell as a result of the water
intake.
Plasmolysis: is the process in which cells lose water in a hypertonic solution.
Plamoptysis: Passage of water from a low solute concentration(hypotonic) into the
cell, is termed plamoptysis.
25. Filtration
May be done under either negative or positive pressure.
Example ; membrane filter made of cellulose acetate. Generally removes
most bacteria but viruses and some small bacteria e.g. Chlamydia &
Mycoplasma may pass through. Thus filtration does not technically
sterilize items but is adequate for circumstances under which is used.
Main use: for heat labile substances e.g. sera, antibiotics.
29. Properties of an ideal disinfectant or
antiseptic
It should
✔Have wide spectrum of activity
✔ Act in the presence of organic matter
✔Have high penetrating power
✔Be stable and effective in acidic and alkaline conditions
✔Not be corrosive
✔Not be toxic and irritant
✔Be safe, easy to use and cost effective
✔Have long shelf life
30. Factors affecting the effectiveness of
antimicrobial agents
✔Population Size
✔Population Composition
✔Concentration or Intensity of Antimicrobial agent
✔Temperature
✔Duration of exposure
✔Local environment
31.
32. Terminology
Thermal death time[TDT]
Thermal death time is how long it takes to kill a specific
bacterium at a specific temperature.
Thermal death point[TDP]
The thermal death point (TDP) of a microorganism is the lowest
temperature at which all microbes are killed in a 10-minute
exposure.
33. Terminology
Decimal reduction time[D-value]
Decimal reduction time (D-value) is the interval of time required, under a
defined set of conditions, to provide a one decimal logarithm (1-log10
) or 90%
reduction in the initial viable bacterial population.
35. Major group of Antimicrobial Agents
▪Phenol and phenolic compounds
▪Alcohols
▪Halogens
▪Heavy metals and their compounds
▪Dyes
▪Detergents
▪Quaternary ammonium compounds
▪Aldehydes
▪Gaseous agents
36.
37.
38. Phenol and phenolic compounds
Joseph Lister, a surgeon, to reduce infection of surgical incisions and
surgical wounds used phenolics back in 1880.
Phenol has the additional distinction of being the standard
against which other disinfectants of a similar chemical structure
are compared to determine their antimicrobial activity. The
procedure used is called the phenol-coefficient technique.
39. Phenol and phenolic compounds
A 5% aqueous solution of phenol rapidly kills the vegetative
cells of microorganisms; spores are much more resistant. Many
derivatives of phenol are prepared and evaluated for their
antimicrobial activity.
Hexylresorcinol, a derivative of phenol, is marketed in a
solution of glycerin and water. It is a strong surface-tension
reductant.
Phenol and detergent together are more effective then only pure
phenol.Hence, in most of the cases it is used in combination.
40. Mode of Action of Phenolics
Phenolic compounds act by disruption of cells,
precipitation of cell protein, inactivation of
enzymes, and leakage of amino acids from the
cells.
41. Alcohols
Ethyl alcohol in concentrations between 50 and 90%, is effective
against vegetative or non-spore forming cells. For practical application a 70%
concentration of alcohol is generally used.
Alcohol is effective in reducing the microbial flora of skin and for the disinfection of
clinical oral thermometers.
Isopropyl Alcohol, Ethyl alcohol are commonly used.
Other alcohols methyl alcohol, propyl alcohol are toxic in nature.
42. Mode of Action of Alcohols
Alcohols are protein denaturants.
Alcohols are also solvents for lipids, and hence they may
damage lipid complexes in the cell membrane. They are
also dehydrating agents. This may account for the
relative ineffectiveness of absolute alcohol on "dry"
cells; it is possible that very high concentrations remove
so much water from the cell that the alcohol is unable to
penetrate
43. Halogens
A. Iodine
A bluish-black crystalline element having a metallic
Luster. It is only slightly soluble in water but readily
soluble in alcohol and aqueous solutions of potassium or
sodium iodide. The element is traditionally used as a
germicidal agent in a form referred to as tincture of
iodine.
44. Iodine
2% iodine plus 2% sodium iodide diluted in alcohol, 7% iodine
plus 5% potassium iodide in 63% alcohol, and 5% iodine and
10% potassium iodide in aqueous solution. Iodine is also used
in the form of substances known as iodophors.
45. Iodophors are mixtures of iodine with surface-active
agents which act as carriers and solubilizers for the
iodine. One of these agents is polyvinyl pyrrolidone
(PVP); the complex can be expressed as PVP-I. Iodine is
released slowly from this complex. Iodophors possess
the germicidal characteristics of iodine and have the
additional advantages of non staining and low irritant
properties.
Iodine
46. Mode of Action of Iodine
Iodine is an oxidizing agent.
Oxidizing agents can irreversibly oxidize and thus inactivate essential metabolic
compounds such as proteins with sulfhydryl groups.
47. Chlorine and Chlorine Compounds
Compressed gas in liquid form is almost universally employed for
the purification of municipal water supplies.
One class of compounds in this category is the hypocholrite.
Calcium hypochlorite, Ca(OCl)2
(also known as chlorinated lime),
and sodium hypochlorite, NaOCl, are popular compounds.
The chloramines represent another category of chlorine
compounds used as
disinfectants, sanitizing agents, or antiseptics.
48. Chlorine and Chlorine Compounds
Medical students were required to wash their hands and soak them in a hypochlorite
solution before examining patients.
Chlorine compounds are very widely used to control microorganisms. Major
applications are in water treatment, in the food industry, for domestic uses, and
in medicine.
Products containing calcium hypochlorite are used for sanitizing dairy equipment
and eating utensils in restaurants. Solutions of sodium hypochlorite of a
1% concentration are used for personal hygiene and as a household disinfectant;
higher concentrations of 5 to 12% are also employed as household bleaches and
disinfectants and for use as sanitizing agents in dairy and food-processing
establishments.
49. Chlorine and Chlorine Compounds
Mode of Action
Cl2
+ H2
O— HCl+ HClO (hypochlorous acid)
50. Heavy Metals and Their
Compounds
Mode of Action
Heavy metals and their compounds act antimicrobially by combining with cellular
proteins and inactivating them. For example, in the case of mercuric chloride the
inhibition is directed at enzymes which contain the sulfhydrvl grouping.
51.
52. High concentrations of salts of heavy metals like mercury, copper, and silver
coagulate cytoplasmic proteins, resulting in damage or death to the cell. Salts
of heavy metals are also precipitants, and in high concentrations such salts
could cause the death of a cell.
Heavy Metals and Their
Compounds
53. Dyes
Two classes of dye compounds which have antimicrobial properties are of
special interest to microbiologists. These are triphenylmethane and acridine
dyes.
Triphenylmethane Dyes
Included in this category are malachite green, brilliant green, and crystal violet.
As a rule Gram-positive organisms are more susceptible to lower concentrations
of these compounds than are Gram-negative ones.
54. Crystal violet will inhibit Gram-positive cocci at a dilution of 1:200,000 to 1:300,000;
10 times this concentration is required to inhibit Escherichia coli. Staphylococcus
aureus is inhibited by malachite green at a concentration of 1:1,000,000; a
concentration of about 1:30,000 is required to inhibit E. coli
Dyes
55. Mode of Action of Triphenylmethane
Dyes
The mode of action of triphenylmethane dyes is uncertain, but
there is speculation that they exert their inhibitory effect by
interfering with cellular oxidation processes.
56. Acridine Dyes
Examples of dyes derived from acridine are acriflavine and tryptoflavine.
These compounds exhibit selective inhibition against bacteria, particularly
staphylococci and gonococci. Gonococci are inhibited by tryptoflavine in dilutions
of 1:10,000,000 to 1:50,000,000. They possess little, if any, antifungal
activity. Presently, they have less application than before the advent of antibiotics
and other chemotherapeutic agents. They are used to some extent for the
treatment of burns and wounds and for ophthalmic application and bladder
irrigation.
57. Synthetic Detergents
Surface-tension depressants, or wetting agents, employed primarily for cleansing
surfaces are called detergents.
Example : Soap, Cetylpyridinium chloride, Sodium Lauryl Sulphate.
Chemically, detergents are classified as
Anionic
Cationic
61. Synthetic Detergents
Soaps reduce surface tension and thereby increase the
wetting power of the water in which they are dissolved.
Soapy water has the ability to emulsify and disperse oils
and dirt. The microorganisms become enmeshed in the
soap lather and are removed by the rinse water. Various
chemicals have been incorporated into soaps to enhance
their germicidal activity.
62. Quaternary Ammonium Compounds
Most compounds of the germicidal cationic-detergent class
are quaternary ammonium salts.
The bactericidal power of the quaternaries is exceptionally
high against Gram positive bacteria, and they are also quite
active against Gram-negative organisms.
Bactericidal concentrations range in1:1000 to1:20,000
Examples : Cetrimide, Ceepryn, Zephirol
63.
64. Application
They are used as skin disinfectants, as a preservative in ophthalmic
solutions, and in cosmetic preparations.
Quaternaries are widely used for control of microorganisms on floors. walls,
and other surfaces in hospitals, nursing homes, and other public places.
They are used to sanitize food and beverage utensils in restaurants as well
as surfaces and certain equipment in food-processing plants.
Other applications are to be found in the dairy, egg, and fishing industries to
control microbial growth on surfaces of equipment and the environment in
general.
65. Mode of Action
Denaturation of proteins, interference with glycolysis, and
membrane damage.
The site of the damage to the cell is the cytoplasmic membrane;
the quaternaries alter the vital permeability features of this cell
structure.
66. Aldehydes
Formaldehyde and Glutaraldehyde are most commonly used microbicidal
compounds.
Formaldehyde
It is a gas that is stable only in high concentrations and at elevated temperatures.
Formaldehyde in solution is useful for sterilization of certain instruments.
Formaldehyde in gaseous form can be used for disinfection and sterilization of
enclosed areas. Formalin and paraformaldehyde are two principal sources of
formaldehyde when it is used for gaseous disinfection.
67. Mode of Action of Formaldehyde
Formaldehyde is an extremely reactive chemical. It combines
readily with vital organic nitrogen compounds such as proteins
and nucleic acids. It is likely that interaction of formaldehyde
with these cellular substances accounts for its antimicrobial
action.
68. Glutraldehyde
A 2% solution of this chemical agent exhibits a wide spectrum of antimicrobial
activity. It is effective against vegetative bacteria, fungi, bacterial and fungal
spores; and viruses. It is used in the medical field for sterilizing urological
instruments, lensed instruments, respiratory therapy equipment, and other special
equipment.
69. Gaseous Sterilising agents
Certain kinds of medical devices that need to be available in a sterile
condition are made of materials that are damaged by heat. Examples are
plastic syringes, blood transfusion apparatus, and catheterization
equipment. The same is true for routinely used laboratory ware, such as
plastic pipettes. Petri dishes, and other equipment, that is packaged and
sterilized ready for use.
70. Ethylene Oxide
Ethylene Oxide is highly flammable. Hence it is mixed with CO2
or feron
The carbon dioxide–ethylene oxide or Freon–ethylene oxide mixtures are non
flammable, and there is no alteration of the microbicidal activity of the ethylene
oxide. The carbon dioxide and the Freon merely serve as inert diluents which prevent
flammability.
Ethylene oxide is a unique and powerful sterilizing agent. Its use for sterilizing
heat- or moisture-sensitive materials in hospitals, industry, and laboratories has
become universal.
71. An outstanding and desirable feature of ethylene oxide is its
power to penetrate. It will pass through and sterilize large
packages of materials, bundles of cloth, and even certain
plastics.
The commercially available apparatus for this purpose is
essentially an autoclave modified to allow the chamber to be
filled with the gas under controlled conditions. The
concentration of ethylene oxide, as well as the temperature and
humidity, are critical factors which together determine the time
required to achieve sterilization.
Ethylene Oxide
72. Practical Application
Ethylene oxide has been established as an effective sterilizing agent for
heat- and moisture-sensitive materials. Effective usage requires careful
control of three parameters: ethylene oxide concentration, temperature,
and moisture. It works at low temperature.
It has been used in the space program by both the Americans and the
Russians for decontaminating spacecraft components.
73. Mode of Action of EtO
Ethylene oxide alkylates DNA molecules and thereby inactivates
microorganisms.
https://youtu.be/wNlKflMx8xM
74. β-Propiolactone
This compound is a colorless liquid at room temperature with a high boiling
point (155°C).
It is not flammable like ethylene oxide but is a vesicant and lachrymator and
consequently must be handled with care. It lacks the penetrating power of
ethylene oxide but is considerably more active against micro-organisms; it is
sporicidal, fungicidal, and virucidal.
75. β-propiolactone is very effective in destroying microorganisms on surfaces.
Low power of penetration coupled with its alleged carcinogenic properties has
restricted its use as a practical sterilizing agent.
β-Propiolactone
80. Tube-Dilution and Agar-Plate Technique
A. Suspension Test
A sample of the bacterial culture is suspended into the disinfectant
solution.
After exposure it is verified by subculture whether this inoculum is killed
or not.
A loopful of bacterial suspension brought into contact with the
disinfectant
A loopful of this mixture cultured for surviving organisms.
Results expressed as ‘growth’ or ‘no growth’.
81.
82. Tube-Dilution and Agar-Plate Technique
B. Minimum Inhibitory Concentration
The chemical agent is incorporated into an agar medium or broth, inoculated with
the test organism, incubated, and then observed for (a) decrease in the amount of
growth or (b)complete absence of growth.
83.
84. Tube-Dilution and Agar-Plate Technique
c. Agar Plate method
A plate of agar medium is inoculated with the test organism, and the chemical
agent is placed on this medium. Following incubation, the plate is observed for
a zone of inhibition (no growth) around the chemical agent. This is particularly
suitable for semisolid preparations. It may also be used for liquid solutions, in
which case the solution is first impregnated in absorbent paper or confined by a
hollow cylinder placed on the agar surface.
85.
86. Phenol coefficient
Phenol coefficient of a disinfectant is calculated by dividing the dilution of test
disinfectant by the dilution of phenol that disinfects under predetermined conditions.
Rideal Walker method: – Organism: Salmonella typhi suspension.
– Temp: 20°C
– Subcultures are performed from both the test and phenol at intervals of 2.5, 5, 7.5
and 10 minutes.The plates are incubated for 48-72 hours at 37°C.
– Growth or no growth
87. Phenol coefficient
Rideal Walker phenol coefficient =
That dilution of disinfectant which disinfects the
suspension in a given time_____________________
Dilution of phenol which disinfects the suspension in
same time.
88.
89.
90. The greatest dilution of the disinfectant killing the test organism
in 10 min but not in 5 min is divided by the greatest dilution of
phenol showing the same result.