Introduction and Scope:

Microbiology is a specialized area of biology (Gr. bios=life + logos = to study) they deals with the study of micro-organisms or microbes. Roughly speaking organisms with a diameter of 1mm or less are microorganisms and fit into the broad domain of microbiology. At present there is general argument to include six major groups bacteria, fungi, virus, protozoa algae and helminthes in micro-organism. These micro-organisms may be seen only by magnifying their images with the microscopes. The study of micro-organism employs certain techniques such as sterilization and use of culture media that are required to isolate and growth them.

Microbiology is one of the largest and most complex of the biological sciences such as it deals with many diverse biological discipline. In addition to studying the natural history of microbes. It also deals with aspect of microbes- human and environmental interaction. These interaction include ecology genetic metabolism, infection, disease, chemotherapy, immunology, genetic engineering.

The branches that come under the large and expanding umbrella of microbiology are categorized into pure and applied science, Pure science included.

1. Bacteriology - It in the study of bacteria the smallest, simplest prokaryotic single called organisms

2. Mycology – It is the study of fungi (echlorophyllous, heterotrophic, eukaryotic spore bearing microorganisms with absorptive nutrition and which characteristically have rigid cell wall chitin and cellulose) a group of organisms that include mold, yeasts , mushroom and puff bells.

3. Protozoology- it is the study of protozoans-animals like and mostly single celled eukaryotic organisms.

4. Virology- it is concerned with the study of viruses. (minute non cellular particles that parasite living things) and viral disease.

5. Phycology- it is the study of algae. simple aquatic organisms ranging from single celled forms to large sea weeds.

6. Parasitology: it is study of parasitism and parasite that included pathogenic protozoa, helminthes worms and certain insects.

7. Microbial ecology: it is the study of interrelationship between microbes and environment.

8. Microbial morphology: it is the study of detailed structures of microorganism.

9. Microbial taxonomy: it is concerned with the classification, naming and identification of micro-organism.

10.Microbial physiology: it is the study of metabolism of microbes at the cellular and molecular levels.

11.Microbial genetics and molecular biology: it is the study of genetic materials, structure and function and bio-chemical reaction of microbial cells in metabolism and growth.

The prominent applied branches of microbiology are:

1.Industrial microbiology-It is concerned with the industrial uses of microbes in the production of alcohol beverages, vitamin, amino acids, antibiotics and other drugs.

2. Agricultural microbiology-It is the study of relationship of microbes and crops with a emphasis on the control of plant disease and improvement of yields.

3. Food microbiology-It deals with the interaction of microorganism and food in relation of food bo-processing food spoilage, food born disease and their prevention.

4. Dairy microbiology-It deals with the production of and maintenance in quality control lf dairy produce.

5. Aquatic microbiology-It is the study of micro organism and their activities concerning human and animal health in fresh, estuarine and marine water.

6. Air microbiology-It deals with the role of aerospona in contamination and spoilage of food and

dissemination of plants and animals disease through air.

7. Medical microbiology-It deals with the fundamental principle and technique involved in the study of

pathogenic organism as well as their application in the diagnosis of infectious disease.

8. Exo- microbiology-It deals with the exporation for microbial life in outer space.

9.Immunology- It deals with the immune system (i.e barely defense)that protects against infection and attempts to understand the many phenomenon that are responsible for both required and innate immunity. In addition to study of anti-body, antigen reactions in the laboratory (i.e serology)

10.Epidemiology and public health microbiology: It concern with monitoring control and spread of disease in communities.

11.Biotechnology: It is the scientific manipulation of living organism, especially at the molecular and genetic level to produce useful products.

12.Modern biotechnology: It deals with the construction of microorganism with specific genetics characteristic by the use of recombinant DNA technology for industrial purpose.

Louis Pasture(1822-1895)

The scientific developmemt of microbiology was started after brilliant work of Louis pasteur(1822-1895).Louis pasteur was originally a chemist, affecting the nine industry of france Lillein 1856.In these days people thought that fermentation was a chemical process. Louis Pasture studied the fermentation; he demonstrated that contamination of rod shaped organism was responsible for faculty fermentation of alcohol. Rod shaped organism oxidize alcohol to organic acid. He established that fermentation was the result of microbial activity and different types of organisms were responsible for different type of fermented product. In the

course of his research, Louis Pasture emphasized the importance of sterilization of equipment used for bacteriological investigation. He developed various methods of sterilization such as:

1.Steam sterilization 2.Autoclave 3.Hot air oven and 4. Pasteurization

He introduced cotton wool plugs for the prevention of aerial contamination of culture media and established that the growth of different micro organisms required different types of culture media .Pasteur disproved spontaneous generation (abiogenesis)of micro organism. He demonstrated that pasteur’s flask of infusion, sterilization by autoclaving always remained sterile until tubes were exposed to air .He proved that all forms of life even microbes arose only for their parents.

After his brilliant work on fermentation, pasture started to investigate (1880) pebrine disease of silk industry, anthrax chicken pox, cholera and rabies (hydrophobia).In those days anthrax was a serious disease of sheep in France. One day by mistake he left chicken cholera culture plate on the working bench for several weeks and found that chicken cholera bacillus lost their pathogenic property but remained their ability to protects the birds against subsequent infection on this observation be discovered the process of alterivated cultures of anthrax (42degree C-43degreeC) and prove that inoculation of such cultures in animals induced immunity against anthrax. In 1888 pastures institute was built in paris by public contribution for preparing vaccine and investigating infectious disease. Louis pasture is remembered as a man who laid the foundation of microbiology. Thus he honored as a father of microbiology.

Robert Koch(1843-1910)

Robert Koch contemporary of Louis pasture, a german general practitioner is called father of microbiology. Anthrax and its transmission was a difficult question because of relation between organism and disease was not fully established. To prove that the germ theory of disease i.e, specific organism produce a specific disease, it requires careful studies. It is not always possible to as certain that organism isolated from a disease lesion or pus or blood or stool or urine are the

cause of the observed disease conditions in 1876 .Robert Koch put the germ theory of disease to the rest of experimentation .Koch established the pure culture technique and made it possible to study the etiology of disease.

Robert Koch showed that a spore forming organism called Bacillus anthracis was the cause of anthrax. Anthrax was epidemic in sheep, cattle and other domestic animals and sometimes also occurred in man. koch isolated the anthrax producing organism in pure from the disease animals and growth organism on the culture media in the pure form and produced colonies and those were called living bacillus.

These living bacillus isolated from isolated from the disease animals were inoculated in healthy experimental animals .After sometimes (incubation period), a healthy experimental animal produced typical symptoms of anthrax and died. Anthrax bacilli with some characteristics were reisolated in their blood. This was clear cut demonstration of casual relationship between microorganism and specific disease. On the basis of their experiment, Koch outlined four rules known as loch postulates.

Koch postulates

1. Disease producing micro-organism must be found in infected human body and it is absent in healthy person.

2. Disease producing micro-organism must be isolated in pure culture on artificial media from infected human body.

3. Pure culture of organism, when inoculated in a healthy susceptible host, must produce the same disease.

4. The same organism must be re-isolated from experimentally host body.

Robert Koch discovered the tubercular bacilli, mycobacterium tuberculosis in 1882, march 24 in berlin, Germany . he discovered vibrio cholera in 1883.

Describe in bacteria with diagram

Bacteria are prokaryotic unicellular organisms having various organelles required for its existence . There are many different types of bacteria . The following description applies to generalized bacterial cell.

Cell wall- cell wall is the outermost layer of bacterial cell which differentiates between external and internal environment. It is about 10-5 nm in thickness and rigid like plastic to some extent and porous. It allows passing substance having molecular weigh less than 10,000. The function of cell wall include:

Supporting plasma membrane, maintaining shape of bacteria and taking part in cell division. When the cell wall to ruptured bubbles of protoplasm will come out and this is known as plasmolysis, where as retracting and detaching of plasma membrane is known as plasmolysis. Cell wall is composed of mucopeptide susbstance, acetyl glucosamine acetyl muramic acid molecule and L-glutamic acid L-lysine. Certain lytic agent such as lysozome lyses tha bacteria of many species by dissolving mucopeptide substance and cleaving acetyl glucosamine from acetyl muramic acid penicillin, bacteracin, novobiocin, gentian violet are known to interfere in the synthesis of polypepetide substance. Death of the bacteria cell occurs due to defective synthesis of cell wall and development of cross wall leading to cell lysis.

Function of cell wall

- Provides shape to bacterium.

- Gives rigidity to organism.

- Protects from environment.

- Contain receptor sites of phages site of action of antibody

- Provide attachment to complement.

- Contain components toxic to host

- Site of the action of colicin

Cell membrane:-

Thin is thin elastic membrane of about 5-10 nm in thickness. It consists of glucose and lipo protein, which acts as osmotic barrier. It permits many solutes and solvents into cytoplasm by passive diffusion, active transport system, facilited diffusion group translocation mechanism . it contains many enzymes required for the bacteria to up take nutrient, such as permease ,protease enzymes of respiratory and cytochrome system and kreb cycle.

Plasma membrane allow the release of extracellular toxins, enzymes etc produced in the cytoplasm. It helps to maintain the consistency of cytoplasm by passing necessary substance into the cell.

Cytoplasm

Cytoplasm is semi solid viscous substance composed of various organic and inorganic substance. It also contain many other things. These are:

a. Ribonucleic acid(RNA)

one single cell contain about 10 thousand RNA. These are protein in nature and are of different types namely transfer (tRNA), messanger(mRNA)and Ribosomal(rRNA).

b.Deoxyribonuclei acid(DNA)

These are the genetic materials and give future generation of bacteria. The bacterium does not have nucleus. The nuclear material are present in different form at the centre of the cell.

c.Mesosome

These are convoluted bodies and they act as the principal centres of respiratory enzymes.

d.Inclusion bodies

These bodies store energy yielding substances. When the bacteria utilize these bodies in the form of energy, those bodies disappear .eg-lipid granuls, polysacchariates granuls and volution granules.

e.Lipid granules

These granules are slightly acid fast .These are also sources of carbon required for energy. The chemical nature of these granules is betahydroxyl sutgic acid.These granules can be stained with sudden black dye or oil red –O.

f. Polysaccarides granules

These are sources of energy for Bacteria. These granules can be strained with periodic acid strength(PAS). Glycogen gives red in colour and starch gives blue colour with iodine.

g. Volutin granules

These are also called meta chromatid granules. These granules are polymeta phosphate in nature and bove intense affinity to basic dye. These are also energy rich compound. Bacteria utilized these granules when there is shortage of lutanes.

Fagella (Flagellum=singular, flagella=plural)

These are the locomotary organ of bacteria flagella arises from cytoplasm of bacteria and consist of filament .Look flagellin and myosin .These are highly immunogenic .these are heat and alcohol bile but preserved by 10%formailn. All bacteria do not contain flagella . A complete

expression of flagella can be obtained by growing into liquid medicine such hazana broth ; hard agar many interfere in the production of flagella there expression are phenotypic begin influenced by physical condition . The thickness of is about 15-20 um and length is several times of bacterium body . the distribution of flagella varies as species of bacteria

The flagella can be demonstrated by silver impregriation method such as fontana’s method, leviditi’s method . the bacteria with do not have flagella, are called artichates . Based on flagella, bacteria may be categorized as follows ;

1.Atrichares : without flagella,eg klebsiella spp, shigella spp

2. menotrichates : single flagella at one eg vibrio cholera

3. Amphitrichates : single flagella at both end .

4. Leopholtrichates : Tuft of flagella

Fimbriae or pili (Singular Pilus)

Fimbriae are flamentous, short ,thin ,straight hair like structure , fimbriae of pili of bacteria differ from flagella in that they are thinner, straight , less rigid and more in number us than flagella . Their length varies from 0.1-0.5 um and less than 4-8nm thick fimbriae can be seen only under the electronic microscope . They are unrelated to motility found on motile as well as non- motile cells . They are best developed in freshly isolated strain in liquid culture . They tend to disappear when they are sub culture on solid medium . They are antigenic .

Spore

Bactrial spore may be defined as cryptobiotic (In greek, krytos = hidden, bio = life ) or latent of life of certain.

Function of pill

1 Adhersion

The fimbriace are mainly associated with adhesive properties which help the organism to attach substrate .

2 Antigen

Fimbriae possess antigenic properties .

3 Sex pill

Sex pilli are found only in male bacteria . They help the male cell to attach with female cells in forming hollow conjugation tube through which genetic material are believed to be transferred from donar recipient cells

Difference between and pilli

Character flagella pilli

Size large small

Thickness +++ +

Appearance Straight Never Straight

Origin Cytoplasmic membrane cell wall

Organ of movement + -

Organ of adhesion - +

Conjugation - +

6 Capsules

It lies immediately outer to the cell wall . All bacteria don’t have capsule . This is rich in carbohydrate which is relatively gelatinous . The capsule is partially antigen and is hapten in nature . It has got immunological determinats when the protein in added to the capsule . It becomes completely antigenic . The antigenic character helps to determine immunological specificity of bacteria. The function of capsule is to protect from bacteriostatic and bactericidal substances such as antibiotics or antibodies . The capsule antiphagocytic in nature .

Spore

Bacterial spore may be defined as cryptobiotic ( In Greek, Krytos = hidden bio = life ) of latent of life of certain bacteria and is forms under unfavourable condition . The unfavorable condition include starration ( lack of food ) dessication and adverse PH, temperature and media . However there are some exceptions , certain bacteri always sporulate even under Favourable condition e.g. Bacillius subtilis . This process of spore formation is known as sporulation .On the another hand certain bacteria do not form spore even under unfavourable condition .The spore is known as resting phase of bacteria spare contain dipicolinic acid and calcium .some example of spore forming bacteria :

Clostridium tetani

Bacillus subtilis

B. steriothermophilus

On the basic of shape,bacteria are classiried as under:

Shape of bacteria(Morphagical classipication)

A:Cocci (GK,Kokkos,meaning berry : Cocci are spherical,oval or bean shape (singular coccus):on the basis of cell division ,arrangement of individual organism, and biological properties, cocci are again divided into six types:-

1: Micrococci (singular micrococcus): The cells are arranged singly or irregularity. They are saprophyte and found in water and air:

e.g. Micrococcus agilis

Micrococus roseus

M. Luteus

2:Diplococci(G.K. diplos = double):The cell division in one plane and remains attached in pairs ,e.g:

Neisseria meningitides (mening coccus),Neisseria

Gonorrhoeae(gonococcus)and streptococcus pneumoniae (pneumococcus).

3:Tetra cocci (GK. Tetra=four)

The cell divides in two planes at right angles to one another and form groups of fours. These rarely produce disease in human.

4:Sarcinae(L.sarcio=totie):The cell division in three planes at right angles to one another and resembles packet of 8,16 or more cells. They are generally found in air and pathogenic species have not been encountered.

5. Strepto cocci ( G.k streptos twisted or curved, kokkos=berry) cell divide in one plane only and are arranged in chain of different length e.g strepto coccus pyogens.

6. Staphylococci ( G.k staphyle = cluster of grapes) : the cell divide in three planes with daughter cells tending to remain in close proximity, which resulted in irregular bunches of cells. They are resemble cluster like a bunch of grapes. E.g

Staphylococcus aureus

B. Bacilli ( Bacillus meanings of rods)

The bacilli are straight or slightly curved or rod shaped cylindrical organisms with rounded end (singular bacillus). According to their arrangement they are divided following type

1. Bacillus :- the cells are arranged singly or irregularly e.g e.coli

2. Diplobacilli:- the cells are arranged in pair e.g anthrax bacilli

3. Streptobacilli:- the cells are arranged in chain of different length e.g streptobacillus moniliformis

C spira

Bacteria are spiral or curved shaped. They are subdivided into two types

1. Vibroid (v. Vibrio= to vibrate):- The bacteria are less than one complete twist or comma shaped e.g v. cholera.

2. Spirilla ( l spira coil):- Spirilla or coiled form of bacteria and have one or more complete turn.

D. Spira chactes ( from spir= meaning coil, chactes meaning hair) . they are relatively longer thin and higly flexible organism having several coils (cork screw like). They are motile and without any flagellum but the cells more an undulation or screw like contraction of protoplasm. E.g t. palladium

E. Actinomycetes (actis meaning ray, mykes meaning fungus) these are branching filamentous bacteria, resembling to the radiating rays of the sun when seen in tissues lesions.

F. Mycoplasma These are organism which lacks cell wall and hence do not possess a stable morphology. They are round or oval bodies with interlacing filaments.

Virus

These are extremely small non cellular obligatory intracellular parasite or particles having dna or rna but not both as genome. The study of virus of virus is a called virology. They are kept border line between living and non-living beings.

Living characteristics

1. They can be multiply

2. They possess genetic characteristics

Non- living characteristics

1. They can be crystallized

2. They do not have complete cell organelles.

Classification of virus

1. Based on nucleic acid

A. DNA virus

Examples: adeno virus

Hepes virus

Varicella virus

B. RNA virus

Examples: polio virus

Measles

Rabies virus, rubella virus.

2. Based on host

a. animal virus

b. insect virus

c. bacterial virus

3. Based on symmetry

a. Helical

b. Icosahedral.

c. Complex

Morphology:

Size

It ranges from 20 nm -200 nm

Structure and shape

The virus consist of nucleic acid surrounded by a protein coat ( the capsid). The capsid enclosed nucleic acid is known as nucleocapsid. The capsid is composed of capsomers which forms morphological units.

Icosahedral is a polygon with 12 corner and 20 facet sides. Each facet is in the shape of equilateral triangle.

Properties of virus:

1. They are extremely small measuring 20nm – 200 nm.

2. They are non cellular organisms ( they do not have cellular organelles like cell wall , cell membrane , golgi bodies etc

3. Hey are obligatory intracellular parasite (they must use host machinery for multiplication and growth.

4. They are kept in borderline between non-living and living beings

5. They contains either DNA or RNA as genome but not both. They are reproduce in large number.

6. Viral genome is enclosed by protein coat called capsid.

7. They are virulent in nature.

Some viral disease

Viral Disease

Pox virus Small pox

Herpes Skin lesions

Adeno virus Some throat conjunctivitis

Flavivirus Japenese encephalitis

Corona virus common cold

Retro virus Aids

In Bacterial growth and cultivation

Bactrerial growth is define as increased in the number of bacteria rather than its size

Bactria growth phase :- There are 4 district phases of lag phase ( Phase of adaptation . It is the time taken by bacteria to adjust into now medium . It deepened on physical and chemical condition, PH of the medium in which they are supported to grow, nutrient, age of inoculums and inoculums size In this phase, metabolism rate of bacteria would be very high . Yje size of bacteria would increase rather than It s number . The time of lag phase ranges from 10-20minut and in some this is even 4-6 hrs depending on generation time of Bacteria.

Log phase

This is the phase were maximum multiplication of bacteria would occuring very high rate and in geometric progression . When the bacteria this phase are barsrred into similar new medium . They st\at multiplying immediate without undergoing through log phase. Besides, the organisms have typical morphology and biochemical reaction . In this phase, organisms are the most susceptible to antimicrobial substance

Stationary phase

This is the phase where there is no further multiplication of bacteria in this phase the bacteria growth is spped. The number of organism remain constants. This is due to shortage of food for bacteria accumulation of toxic metabolic product and lowering of pl of medium due to production of acid through the metabolism of carbohydrate .As a result growth is terminated. In this phase total yhe count wozurd of carbohydrate .As a result growth is terminated .this phase can sustain for to several bonus.

Death/Decline phase:

After various period of stationary bacteria cells design to die .This is due divergences between the living and dead bacteria, cassation of growth in the stationary phase and accumulation of toxic metabolic products. In this phase bacteria are prove to digest themselves due to autolytic enzymes and heterolytic enzymes coenzymes product by other bacteria including appearance of hazard shape cells and change in staining reaction ..

Culture of bacteria

Bacteria culture are defined as the active growth of bacteria of bacteria organisms on the artificial nutrients medium in the laboratory for optimum growth of micro organism laboratory provides necessary nutrients material (chemical substance ) and suitable physical environment .Bacteria culture is essential for:

1:Isolation and identification of organism from clinical specimens.

2:Performance of antibiotic sensitivity test.

3:Performance of antigen for serological diagnosis of microbial disease.

4:Ezitimate of various counts of infective disease .

5:To maintain stock culture.

6:Demonstration of their bio-chemical properties.

In the cultivation of micro organism, various types of culture types of culture media are needed according to their nutritional requirement .some organisms grow in general purpose medium and fastidious organisms do not grow in general purpose medium . Different types of microorganisms grow in same vulture medium and produce different types a colony. The knowledge of colony characteristics helps in identification of microorganism performing antibiotic sensitivity test or preparation of antigen. Pure bacterial culture can only one species of microorganisms. Isolation of bacterial species from mixed bacterial population is called pure culture techniques.

Culture media:

Pathogenic bacteria are heterotrophic, they derive their nutrition from the tissue in which they grow but food requirement of pathogenic bacteria are different from one organism to another organism.

1×8=8

4×2=8

2×2=4

Micro organism like all other living organism require basic nutrient for their growth and development. The nutrient preparation (food materials) on or in which organism are grown in the laboratory is called culture medium and the growth itself is called a culture.

Culture media supply nutrient substances that are required for growth and development of microorganisms in vitro culture media are used:-

1. To growth micro-organisms for isolation and identification purpose

2. To study of their biochemical properties.

3. Production of antibiotics and vitamins.

4. To determine antibiotic sensitivity test.

5. To preserve bacterial cultures.

6. Production of different types of fermented food products. Eg alcohol ,wine ,beer.

Types of culture media.

According to their state, culture media are divided into the three type.

1. Liquid media.

2. Semi-solid media.

3. Solid media.

1. Liquid media:

This media in liquid in form. These media are also called broth media. Agar is not used while making media. Example of broth media is nutrient broth. Glucose broth selenite f broth.

2. Semi solid media

These media are semisolid in form 0.5% of agar is used while making semi-solid examples: cary blair transport medium and sim media.

3.solid media solid media are solid inform while making solid mdia 2% agar is used. Examples of solid media is nutrient agar, blood agar, macconkey agar etc.

According to their purpose media are divided into following types:

1. General purpose or basal media:

General purpose or basal medium grows most of the micro-organisms and these medium are commonly used for isolation and identification purposes but fastidious organisms will not grow. In this medium for example nutrient both and nutrient agar.

2. Enriched medium: enriched medium is used for ht growth of fastidious organisms which do not grow on general purpose medium. To make a medium enriched extra nutritional substance is required such as blood, serum , egg and body fluid etc. example of enriched medium is blood agar, chocolate agar etc.

3. Enrichment medium: these medium are always liquid in form. These medium favour the growth of one species of micro-organism than other species which are present in pathological specimen. Example : selenite f broth, alkaline peptone water.

4. Selective medium:- these media select or allow growing one type of organisms and inhibit to other group of organisms. Example : macconkey agar, Lowenstein Jensen medium.

Controls of micro organisms

control fefers to the reduction in numbers and activity of the total microbial flora. The principle reason for controlling microorganisms are :

To prevent transmission of disease and infection.

To prevent contamination by or growth of undesirable.

To prevent deterioration and spoilage of materials by micro-organisms.

Definition of terms

Sterilization

It is the process to make free of an article from the living micro-organisms, bacteria and their spores without destroying its quantity . an abject or substance is sterile or non-sterile, it can never be semi-sterile.

Antiseptic

It is a chemical substance which kills or inhibits the growth of microorganism and is sufficiently non toxic so that it is used for animate substances.

Disinfectant

It is a chemical substance which kills or inhibits the growth of microorgansisms and is sufficiently toxic so that it is used for in animate substances.

Disinfection

It is the process to kills or inhibits the growth of vegetative forms of microorgansisms in the inanimate substance with the use of disinfectants.

Sanitizer

An agent that reduce microbial population to safe level as judge by public health requirements. It is usually chemical agent that kills 99.9% of growing bacteria sanitizers are commonly applied to inanimate objects and are generally employed in daily care of equipments and utensils.

Germicide

An agent that kills the growing forms but not necessarily the resistant spore forms of germs in practice a germicide in almost the same thing as a disinfectant but germicides are commonly used for all kinds of germs for any application.

Anti microbial agent

One that interfers with growth and metabolism of microbes.

Mode of action

Damage to the cell wall or inhibition of cell wall synthesis.

Alternation of the permeability of the cytoplasmic membrane

Alternation of the physical or chemical states of proteins and nucleic acid.

Inhibition of enzyme action.

Inhibition of protein and nucleic acid synthesis.

Principle and methods of sterilization

Priniciple of sterilization

Destruction of organisms by oxidation of cellular constituents.

Destruction of organisms by coagulating the cellular constituents.

Screening of organisms from product.

Killing of organism by brusting.

Killing of organisms by mutation on genetic level.

But sterilization depends on

1. Nature of material to be treated.

2. Types of organisms.

3. Environmental condition.

Methods of sterilization

There are various methods of sterilization. these method are selected based the materials that are to be sterilized.

Physical agents.

1. Heat :- dry/moist

2. Radiation.

3. Filteration

4. Osmotic pressure

Chemical agents

1. Alcohol

2. Aldehyde

3. Dyes- aniline and acridine compounds

4. Halogens

5. Phenols

6. Surface active agents

7. Metallic salt.

Dry heat of sterilization

Dry heat kills microorganism by promoting oxidative destruction of cell constituent.

a. Red heat:- heating till the article becomes red. E.g inoculating loops,inoculating wires, kimura spatula. It is used to sterilize metallic object. Eg needles, forceps.

b. Flaming:- just flaming the sterilizing materials. E.g mouth of test tube , flasks ,glass , slides. The article is passes over flame without allowing it to become red hot.

c. Hot air oven: sterilization at 160◦c for one and half hour. This temperature destroys all bacteria. This temperature is controlled into a box like machine called hot air oven. Eg glass wares, test tubes, petridishes, oils, powders.

Sterilization temperature Holding time

160. c 90 minute

180 c 30 minutes

Sterilizaton control through

1 Brown’s tube with green spot .

2 Spore of non oxygenic of strains of clostridium tetani

3 Thermo copules

In generation : This method is employed fof the destruction of infection materials .

The soiled dressing, heading pathlogical materials like sputum, stoo; and carcasses are reduced to asher by burning .

Moist beat method of strelization .

Moist headt kills the microorganisms by coaguanisms by coagulation and denaluing their enzyme and protein

Sterilization below 100c

Pasteurization :- Exposure of milk into high heat for short period

There are two main methods

(i) Flash method : Exposure of milk at 73c for 15.20 second .

(ii) Holder method : Exposure of milk at 60c for 30minuts

Temperatuer at 100c

1 Jyndallizaton

John tidal discovered this method of sterilization . the vegetative cell of bacteria is killed in 100 but their spore are restant to the boiling temperature at 100c . The culture media are heated at 100c in water or steamed for 30 minutes each on there sucersive days . The idea of this method is that vegetative cell destroyed 100c and remaining spore will germ inate during storage internal and change into vegetative

cell are killed on subsequent heatin . This method is used for sterilization of egg or serum in method because spore will not germinate in water .

2 Boiling at 100c

This is the simplest, easiest method and doesn’t required any special instrument vegetative cells of bacteria ,virus, fungi are killed at boiling temperature but bacterial spores aresistant to this temperature if spore are present in medium of instrument , this medium is in adutate for sterilization purpose . When other methods aren’t available of abducted steriling is not required in that condition instrument such as ,dyring , clothes etc are boiled in water for 30 minutes . Water used for drinking purpose and other liquid food is also sterilization by boiling for 15-30 minute.

3 Temperature anove 100c

Autoclave

The laboratory apparatus designed to use steam under pressure for sterilized heat stable material called an autoclave. Autoclaving provide moist heat at temperature higher than 100c, the boiling point of water under normal atmosphere pressure. The steam is biocidal as it is on the color article of the load it released thermal energy and moisture which together the microbial proteins. It has the advantage of rapid heating, penetrating and moisture in the microbial protein .It has the advantage of rapid heating ,penetrating and moisture in which facilitates the coagulation of proteins.

Time and temperature required for sterilization by steam under in the autoclaves are given below:-

Tempurature( 0c) Pressure above atmosphereic pressure(lb\in^2) sterilization holding

30 mins

115-118c 10lb/IN2

15 min

121-124c 15lb/in^2 3 min

134-138c 30 lb/in^2

Uses

The autoclaves is used to sterilized only thing that is not injures or destroyed by steam and high temperature .This includes most types of olid and liquid media ,solution ,rubber,tubing,stopper discarded culture and contaminated media prior to wasting etc.

Infection

The invasion of the body by pathogenic microorganism is called inflection.

Or

Invasion or the colonization of micro organism inside the body.

Invasiveness

The abitily of nucro-organism to enter a host grow and reproduce within the host and throughout its body .Invasion of the body any of various agents industry:-

1.Bacteria

2.Fungi

3.viruses

4.protozoans

5.worms and its reaction to them or their toxic.

Disease:

Inflection results in any change from a state of health showing of sign and symptoms is known as disease:

Sources of inflection

1.Humans

2.Animals

3.Insects

4.soil and water

5.food

Types

Endogenic

Exogenic

1. Humans-The commonest sources of infection for human are human themselves. The parasite may originate from a patient or a carrier .A carrier is a person who harbor the pathogenic micro organism without suffering from only ill-effect because of it.

2. Animals:-Many pathogens are able to infect both human being and animals. Animals may therefore sources or human inflection .Inflection disease transmitted from animals to human beings called zoo noses.

Zoonotic disease may be bacterial (playuge from rate ) viral (rabies from doges ) protozoal (toxoplasinosis from cats) helmnthic (hydatid disease from dogs)

3 Insects – Blood sucking insects may transmit pathogens to humn being . This disease so caused are called arthropod horde disease . Inscts such as mosquitoes , ticks, mites , flics flas and like that transmit infection are called vectors.

Female Anopheles mosquito cause malaria a Ades acgypti cause dengue virus .

4 Soil and water – some pathologiescan survice in the soil for long period a spoies of tetanus bacilli may remain viable in the soil for several decades and save as the sources of infection . Fungai ( Histoplasin capsulation, no cardia ) and aso parasites such as roundworm and hookworm survice in the soil and cause human infection .

Water may acts as the sourse of infection either due to contravention with pathogenic microorganism (cholera vibrio,infective hepatitis virus ) or due to the presence of aquatic vectors (cyplops in guinea norm infection ).

5 Food – contaminated food may acts as a sources of infection . The presence of pathogens in food may be due to external contamination ( food poisoning by staphylococcus or due to pre – exist ill infection in meal or other animal products (Salmonellas) .

Types of infection. (Infections fall into general categories)

a) Exogenous infection

Exogenous or those that originate outside the body. For example common cold, uncooked eggs, meat or poultry.

b) Endogenous infection

Endogenous infection which occur when the bodys resistance is lowered. For examples any no. of factors-lack , prolonged exposure to extreme cold or moisture and so on can lower the bodys resistance, opening the way for an endogenous infection.

Methods of transmission of infection

a. Contact

b. Vechile

c. Vector

a. Contact

1. Direct transmission: contact with between unhealthy people and susceptible host person to person transmission. No intermediate host is required. This is direct contact includes physical contact with the diseased person.

Kissing and sexual intercourse may also be the reason of direct transmission of infection (disease).

Common cold, influenza causing agent, viral disease , hepatitis b , measles, small pox , anthrax.

2. Indirect transmission: the route of transmission of disease from infected host to susceptible host through intermediate object mostly non living things i.e towel, formit, eating, utensils , thermometer, syringe etc. disease : bacillary, dysentery, typhoids, hiv, hepatitis.

3. Droplet transmission: infection is due to droplet nuclei which travels only a short distance coughing, talking, sneezing etc are the causes of droplet infection . e.g tuberculosis, whopping cough, pneumonia.

b.vechile transmission

intermediate thing is required for the transmission of disease. E.g water borne, air borne, soil borne, food borne.

1. Water borne : the disease spread via water is water borne disease. Due to contamination of water from sewage and other sources and consumption of untreated water.e.g cholera, typoid, dysentery, poliomyelitis.

2. Air borne : air is polluted by droplets, aerosols microorganisms while sneezing, coughing, talking etc from the diseased person. The susceptible host may ctch the disease if exposed to the environment contaminated with various microorganisms .eg common cold, influenza , measles.

Prevention:

- Uses of masks.

- Immediate treatment of the diseases person

3. Soil borne : mainly the parasite disease are transferred like hookworm, roundworm, bacterial disease like tetanus.

Prevention: use of shoes.

4. Food borne : organisms ingested food consumption without trement. The released of toxins by microorganisms causes the food poisoning. Eg c boterlinum, s. typhi, staphylococcal aureus.

b. Vector transmission

Mainly arthropods are involved in the transmission vector borne transmission can be divided into a types.

1. Mechanical transmission

2. Biological transmission

1. Mechanical transmission : it is also known as passive transmission . the multiplication of the microorganisms doesn’t take palce in this case. E.g bacillary dysentery, amoebic dysentery etc.

2. Biological transmission: it is also known as active transmission complex than the other one. Mosquito palys major role in active transmission and multiplication takes place in the vector. Eg malaria, encephalitis, filiarisis

Prevention- use of net , destruction of water puddles.

Disease progession

1. Infection :the organism begins to grow in the host

2. Incubation period : the time between infection and the appearance of disease symptom some disease like influenza have short incubation period.

3. Acute period : the disease is act its height with over symptoms such as fever and chills.

4. Decline period: disease symptoms are subsiding the temperature falls, usually following a period of intense sweating and feeling of well being develop.

5. Convalescent period: the patient regains strength and returns to normal.

Hospital acquired infection:

Hospital associated infection hospital acquired infection hospital infection or nosocomial (nasocomio means hospital) infection is define as infection developing in a patient after admission to the hospital, which was neither present nor in its incubation period when the subject entered the hospital such as infection may manifest during the stay in the hospital or sometimes after the patient is discharged .

Rule of transmission of infection in hospitals.

1 contact spread :- It is the principle route of transmission of hospital acquired infection it may be by direct contact spread from person to person ( staphylococcal and streptococcal ) or by ,in direct spread via contaminated hand or equipment .

2 Air borne spread

Inhalation of droplets, droplets nuclei and dust from bedding floors

3 Oral infections.

4 Parental route

With the of single use disposable needles , syringe and other devices

5 Self infection

Self infection may occur due to transfer into the of staphylococci and streptococci carried by the patient in his nose and over his skin of of coliform bacilli and anaerobes from his bowel during surgery

Prevention

1 The prevention of sterile instruments, dressing surgical gloves , face masks, theater clothing and fluids .

2 Hand washing after any procedure involving nursing cave of close contact with the patient .

3 Rational antibiotics prophylaxis

4 Proper investigation of hospital acquired infection and the treatment of the patient and carrier .

Different hospital infection causative agents .

Urinary tract infection – Escheria coli klebsiella spp, proteus spp

Respiratory tract infection – Haemophilus influenza, streptococcus pneumonia Staphylococcus aurous .

Wound and skin infection – step aurous ,ecoli, proteus

Gastrointerestinal infection – salmonella spp, shigella sonnei

Eye infection - stap ureus, pseudomonas .

Chain of infection

1 Source of infection

2 Reservoir

3 Portal of exit

4 Mode of transmission

5 portal of entry

6 Susceptible host .

Oral microbiology

Oral microbiology is the study of the microorganisms of the oral cavity and the interactions between the oral microorganisms with each other and with the host of particular interest is the role of oral microorganisms in the two major dental diseases. Dental carries and periodontal diseases.

The mouth harbours a diverse, a bundant and complex microbial community. This highly diverse microflora inhabits the various surfaces of the normal mouth. Bacteria accumalte on both the hard and soft oral tissues in biofilms.

Bacterial adhesion is particularly important for oral bacteria.

→ oral bacteria have evolved mechanisms to sense their environment and evade or modify the host. Bacteria occupy the ecological niche provided by both the tooth surface and gingival epithelium. however a highly efficient innate host defence system constantly monitors the bacterial colonization and prevents invasion of local tissues.

A dynamic equilibrium exits between dental plaque bacteria and the innate host defense system.