Etiket Arşivleri: disinfectants

Antiseptics and Disinfectants


  • Sterlization

  • Freeing of an article, surface or medium by removing or killing all micro-organisms including vegetative form of bacteria, spores, viruses, fungii

  • Disinfection

  • Destruction or inhibition of growth of all pathogenic organisms (bacteria, viruses, fungii) on non living surfaces

  • If spores are also killed process is Sterlization

  • Antiseptics

  • These are chemical substances

which inhibit the growth or kill micro-organisms on  living surfaces such as skin & mucous membrane.

  • Properties of good antiseptic/ disinfectant


2.Non  staining &  good odour

3.Active against all pathogens

4.Active in presence of pus, blood & exudates

5.Rapid acting

6.Non irritating to tissues / non corrosive

7.Non absorbable

8.Non sensitizing/

  • Mechanisms of action of antiseptic and disinfectants

  • Oxidation of bacterial protoplasm

–Potassium permagnate, H202, Halogens

  • Co-agulation (denaturation) of bacterial proteins & disrupt cell membrane

–Phenols, chlorhexidine, alcohols, aldehydes

  • Detergent like action ↑ permeability of bacterial cell membrane

–Cetrimide, soaps

  • Classification

  • Phenol derivatives:

–phenol, cresol, hexachlorophene, chlorohexylenol (dettol)

  • Oxidizing agents:

–Hydrogen peroxide.

  • Halogens:

–Iodine,  chlorine,  chlorophores.

  • Biguanides:


  • Quaternary ammonium:


  • Phenol

  • Earliest used, reference standard

  • Protoplasmic poison,

–injures tissues & cells at high conc causes skin burn

  • MOA:

–denaturating bacterial protiens.

  • USES :

–To disinfect urine, faeces, pus, burns.

  • Extremely irritating, corrosive

  • CRESOL (Lysol)

  • Methyl Derivative of phenol, less damaging to tissues than phenol.

  • 3-10 times more active

  • used for disinfection of utensils, excreta & for washing hands.

  • Chloroxylenol (Dettol)

  • Phenol derivative

  • Does not co-agulate proteins,

  • Non corrosive,Non irritating to skin

  • Commercial 4.8 % solution used for surgical antisepsis

  • Skin cream and soap: 0.8%

  • Mouth wash 1%

  • Hexachlorophene

  • Commonly incorporated in soap

  • Effectively only against Gm+ve

  • Slow but persistant action

  • >2% preparations banned

  • Oxidizing agents

  • Potassium permagnate:

– Purple crystals, highly water soluble, liberates oxygen which oxidizes bacterial protoplasm.

–Used for gargling, irrigating wounds, urethra (condy`s lotion diluted solution of 1:4000  to 1:10,000 )

–High conc cause burns

–It is also used to disinfect water in ponds.

–Stomach wash in alkaloidal poisoning

  • Oxidizing agents

Hydrogen Peroxide

–liberates nascent  oxygen which oxidizes necrotic matter & bacteria.

–Helps in loosening  &  removing  slough,  ear wax etc.

Benzoyl Peroxide

–Widely used drug for acne.

–liberates O2 in presence of water which kills bacteria, specially anaerobes

  • Halogens

  • Iodine,

  • Iodophores,

  • Chlorine,

  • Chlorophores

  • Iodine

  • Rapidly acting broad spectrum (bacteria, fungi,virus)

  • Acts by iodinating and oxidizing microbial protoplasm.

  • Used for cuts, degerming skin before surgery.

  • Adverse effect: cause burns & blisters

  • Iodophores

  • Known as povidine iodine.

  • Non toxic, non staining prolonged action.

  • Used on boils, furunculosis, burns, ulcers, tinea, surgical srub, disinfecting surgical instruments, non specific vaginitis.

  • Chlorine

  • potent germicide. Kills pathogens in 30 sec. used to disinfect urban water supplies.

  • 0.1 to 0.25 ppm

  • Cholorophores

(1)  Chlorinated lime (bleaching powder)

–obtained by action of chlorine on lime.

–used to disinfect drinking water

(2)  Sodium hypochlorite

– Powerful  disinfectant used in dairies for milk  cans.

–Too Irritant to be used as antiseptic.

–Root canal therapy in dentisry

  • Biguanides

Chlorhexidine: (Savlon)

– Acts by disrupting bacterial cell membrane & denaturation of bacterial proteins

– Non irritant ,more active against gram +ve     bacteria.

–Used in for surgical scrub, neonatal bath, mouth wash &  general skin antiseptic.

–Most widely used antiseptic in dentisry 0.12-0.2% oral rinse or 0.5 -1 % tooth paste

  • Quarternary ammonium antiseptics


  • Detergents: Cidal to bacteria, fungi & viruses.

  • Act by altering permeability of cell membrane

  • Efficiently remove dirt and grease

  • Widely used as antiseptics & disinfectants for

surgical   instruments, gloves etc

  • Combined with chlorhexidine (savlon)

  • Soaps

  • Anionic detergents

  • Weak antiseptics with cleansing action

  • Washing with soap and warm water one of the most effective methods of preventing disease transmission

  • Affect only Gm+ bacteria

  • Alcohols

  • Ethanol

–Antiseptic, cleansing agent at 40-90% conc.

–Act by precipating bacterial proteins

– Irritant, should not be applied on mucous membrane, ulcers, open wounds.

  • Aldehydes (Formaldehyde)

  • Used for fumigation.

  • 37 % aqueous solution called as formalin.

  • Protoplasmic poison , denaturates protiens.

  • Used for preserving dead tissues.

  • Use as antiseptic  restricted due to bad odour & irritation

  • Glutaraldehyde is a better sterlizing agent

  • Acids

Boric acid

  • weak antiseptic , bacteriostatic.

  • used for mouth wash, irrigation eyes, glossitis.

  • Adverse effect: vomiting ,abdominal pain on systemic absorption.

  • Metallic salts


  • Silver sulphadiazine is active against pseudomonas seen in burns patient.

  • Silver nitrate highly active against gonococci


  • Mild antiseptic, used as eye wash, ear drops.

  • Dyes

Gentian violet:

– Active against bacteria (gram + ve), fungi

–Used on chronic ulcers, furunculosis, bed sores, ring worms.


–Active against  gram +ve bacteria & gonocci

–suitable for chronic ulcers & wounds

–Do not retard healing, non irritant

  • Ectoparasiticides

  • These are drugs used to kill parasites that live on body surfaces

lice → cause pediculosis (hair infection)

mites → cause scabies(skin infection)

  • Drugs used are







  • Permethrin

  • Broad spectrum causes neurological paralysis in insects.

  • 100 % cure rate nearly

  • Single application needed in most  cases.

  • Few patients experience itching ,burning.

  • first drug of choice for scabies & pediculosis.

Scabies:    apply  all over the body except face & head . Wash  after 8- 12 hrs.

 Head louse:    massage about 30 g in to scalp  and wash  after  10 min.

  • Lindane

  • Broad spectrum insecticide which kills lice and mites by penetrating their chitinous cover

  • Properties similar to permethrin.

  • Cure rate low & resistance seen.

  • Disadvantage: being lipid soluble CNS toxicity like vertigo , convulsions seen.

  • Application similar to permithrin.

  • combination with benzyl benzoate is more effective.

  • Benzyl benzoate

  • Oily liquid with aromatic smell.

  • Cure rate 76 – 100% ; second application required after 24 hrs.

  • Toxicity is low. Application similar to permethrin.

  • Use has declined due to skin irritation.

  • Contra indicated in children because of neurological symptoms & skin irritation.

  • combination with lindane highly effective.

  • Crotamiton

  • low cure rates

  • Better results if applied for 5 days in children

  • Less irritation and toxicity

  • May be preferred in children as second choice

  • Ivermectin

  • Anti helminthic drug which has been recently found effective against scabies & pediculosis.

  • A single 0.2 mg /kg ( 12mg in adults) has 91- 100 %  cure rate.

  • Contra indicated in children < 5yrs , preganant & lactating women.

Evaluating the Effectiveness of Antibiotics, Antiseptics, and Disinfectants

Antiseptics, disinfectants, and antibiotics can be referred to as chemical anti-microbial agents, in contrast to physical antimicrobial agents such as heat and radiation. Microbiologists usually distinguish between antiseptics and disinfectants in the following way. Antiseptics are preparations of chemicals that are meant to be applied to the skin or other living tissue. Examples are chemical preparations designed to treat wounds or infected throats. Alcohol, probably the most widely used antiseptic, denatures proteins, extracts lipids, and dehydrates cells, all of which probably contribute to the effectiveness of alcohol as an antiseptic. Iodine is another excellent antiseptic, though its effects on microbes are not understood. Heavy metals are also used in antiseptic preparations; for example, laws require that silver nitrate be applied to the eyes of newborn humans, especially to prevent the transmission of gonococci from mother to infant.

‎Laboratory‎ > The Techniques of Pure Cultures


     Recognition of media which used  for cultivaring microorganisms and their preparation and sterilization. Learning of to colony selection techniques with pure culture techniques and inoculation of the cultures to different media by transferring techniques.


      The Techniques of Pure Cultures  

     Bacterial growth on/in a medium is called a culture. Microbiology laboratories work with pure cultures. A pure culture is when there is onlyone microorganism growing in/on the medium. The transferring of a bacterium from a stock culture to either a solid or liquid medium is called inoculation. Inoculating a bacterium on/in a sterile medium ensures the purity of a culture. Properly transferring a bacterium without contamination is called an aseptic transfer. Many steps are taken to ensure that neither the bacterium nor the medium is contaminated. Aseptic Techniques are the precautionary measures taken to prevent contamination of pure cultures and sterile laboratory equipment. Treat all organisms as potential pathogens. Many of the organisms can be opportunistic in their abilities to cause infection. Microorganisms in the lab atmosphere may come to rest on the desktop between classes and overnight, so disinfect lab top thoroughly before and after each lab period. This is accomplished by spraying the lab top down with a commercial disinfectant or a 10% bleach solution and allowing this to stand for a minute. You may then wipe down the bench with the paper towel.

Disinfection is the destruction or removal of infectious or harmful microorganisms from nonliving objects by physical or chemical methods. Heating process developed by Pasteur to disinfect beer and wines is called Pasteurization. It is still used to eliminate microorganisms from milk and beer. Not all microbes are destroyed by pasteurization. Chemicals used to disinfect objects are called disinfectants. When this treatment is directed at a living tissue, it is called antisepsis and the chemical is called antiseptic. An antiseptic is a solution used to disinfect the skin or other living tissues. Disinfectants are strong chemical substances and are more destructive to living tissues than antiseptics. An antiseptic is a solution used to disinfect the skin or other living tissues. Disinfectants are strong chemical substances and are more destructive to living tissues than antiseptics.


·       Nutrient Agar

·       Nutrient broth

·       Autoclave

·       Beaker

·       Balon Tube

·       Distilled Water

·       Bunson Burner

·       Stirring magnet

·       Cotton

·       Rope

·       Flask

·       Test Tubes

·       Aliminium foil

·       Electrical heater

·       Sterile pipettes

·       Sterile petri dishes

·       Escherichia coli in Nutrient broth

·       Sterile Nutrient agar slant,plate and deep

·       Needle

·       İnoculation loop

·       Alcohol

·       Dilution tubes


     Preparation of Nutrient broth: 3.2g of Nutrient broth media was taken and was placed in the beaker.A magnetic stirrer was added.After 400ml of distilled water was added in the beaker.İngredients was mixed.This mixture was distibuted into test tubes about 5-6ml for each tubes.Next, mouth of tubes were closed by

Results and Calculations


İn this experiment we learned to prepare different media according to a certain microorganisms and a certain purposes. These media are anaerobic, synthetic, transport, enriched, selective, differential and microbiological assay media. For example; in anaerobic media; oxygen is removed from media with reducing agent, in synthetic media; their chemicals and concentration is known and identified, in transport media; microorganism is transferred from place to other place temporarily, in enriched media; number of scarce microorganisms are increased, but during this process growth of other microorganisms are not prevented, in selective media; growth of a special microorganisms is supplied and growth of other microorganisms are prevented, in differential media; appearance and size of microorganisms are determined with indicator, in microbiological assay media; concentration of some substances are measured. These media are prepared from nutrient broth and nutrient agar that broth represents liquid media and agar represents solid media.

Some media are slant media shape some media also are vertical shape. Slant media provide a large surface area so slant media is convenient for aerobic organisms, in vertical (deep) media, microorganism is cultivated toward the penetration of media and Petri plate also supplies a large surface area and because of this it supplies growth of microorganisms in a short time.

Finally; sterilization of media and equipment were learned during experiment. Moreover, required criteria one by one was told us. For sterilization, applied processes are classified as physical and chemical methods. Physical methods are heat, wet sterilization, tyndallization dry heat sterilization, radiation, freezing and bacteriological filtration. Chemical methods are salt, phenol and phenol derivatives, halogens, and alcohols. Chemical and physical methods and their effects on the microorganisms and equipment were learned and examined.

In this experiment, transfer of E. coli tried to learn with a certain transfer techniques, that these techniques are Broth to Broth, Broth to Slant, and Broth to Deep Transfer. Certain results were obtained from these transfers. For example; the formation of microorganisms were observed at broth to broth transfer and there was turbidity, at broth to slant transfer propagation of microorganisms were observed on the slant surface, at broth to deep transfer there were the formation of microorganisms but they were decreasing from above to deep, at slant to broth and at plate to broth transfers turbidity was observed and there were the formation of microorganisms. Meanwhile; petri plates were also examined against the formation of microorganisms, and at finger press; microorganisms were observed, another petri plate had been exposed to cough that a few microorganism was observed, and finally; at another petri plate finding a hair there was no the formation of microorganisms.

In here; we understood that nutrient agar slant and deep media are more suitable for preservation of microorganisms in a long time. In addition; when the microorganisms live they produce toxic materials and these toxic materials spread out fast in broth media. However; slant and deep media slow down the expansion of toxic materials. Because of this some microorganisms are preserved in the slant and deep media in order to protect a long time.

As a result, we say that we learned transfer techniques and, inoculum and incubation of microorganisms. In addition; we learned that when the transfers of microorganisms are transferred sterilization of media, environment and using apparatus must be taken care sufficiently, and must be rendered sterile.

Laboratory‎ > ‎Anticeptics and Disinfectants


Antimicrobial chemicals have killing effect on microorganisms. Anticeptics have killing effect on living organisms, whereas disinfectants are used to sterilize instruments.In this experiment we have examined the elimination effects of anticeptics (zeption, formaldehyde and ethyl alcohol) on the growth of Staphylacoccus aureus and E.coli bacterias.


‘Antimicrobial agents’ are pesticides that control unwanted microbes on inanimate objects, in water, and on selected foods under certain circumstances. These pesticides are almost always chemicals, and they act by killing or inactivating microbes that are pests. Antimicrobial pesticides include the disinfectants used in swimming pools, drinking water supplies, and in hospitals to control microbes that can cause disease.

“Antimicrobial agents” means:

1.     Disinfectants intended to destroy or irreversibly inactivate infectious or other undesirable bacteria, pathogenic fungi, or viruses on surfaces or inanimate objects;

2.     Sanitizers intended to reduce the number of living bacteria or viable virus particles on inanimate surfaces, in water, or in air;

3.     Bacteriostats intended to inhibit the growth of bacteria in the presence of moisture;

4.     Sterilizers intended to destroy viruses and all living bacteria, fungi, and their spores, oninanimate surfaces; or

5.     Fungicides and fungistats intended to inhibit the growth of, or destroy fungi (including yeasts) pathogenic to man or other animals on inanimate surfaces;

6.     Commodity preservatives and protectants intended to inhibit the growth of, or destroy bacteria in or on raw materials (such as adhesives or plastics) used in manufacturing, or manufactured products (such as fuel, textiles, lubricants, and paints); or

7.     General use algicides labeled for use in:

i. Swimming pools, hot tubs, whirlpools, spas, ornamental ponds, fountains, fish tanks, and waterbeds;
ii. Water, wastewater and sewerage treatment plants, but only where there is a controlled inlet and outlet; and

iii. Industrial, commercial, and manufacturing processes.

ALCOHOLS – Ethyl or isopropyl at a concentration of 50-70% are used for some surfaces where a rapid evaporation of the chemical and leaving no residue may be important, such as on laboratory equipment, etc. Alcohols are low in sporocidal activity and must remain wet on the surface for several minutes to achieve any reasonable disinfection.

ALDEHYDES – Formaldehyde or more usually glutaraldehyde are used as instrument and catheter disinfectants. The glutaraldehyde is the basic chemical for various trademarks, such as Cidex, or Sonacide and newer ones such as Sporocidin or Glutacide or Totacide, etc. These are used for disinfectants or sterilization of instruments and catheters but not for environmental surfaces. They may also be used for pipettes and clinical thermometers, etc.

– The term detergent refers to a removal of soil or dirt and various types of detergents are available. The anionic detergent such as soap and sodium lauryl sulfate and its close chemical relative which are the ingredients in the various dish and laundry detergents have very low level in antimicrobial activity and work by the removal of dirt and microorganisms and rinsing them down the drain.

AGENTS – Ethylene oxide as a gaseous agent may best be used as a sterilant, but has been used in liquids for antimicrobial action. The use of formaldehyde as a liquid at the 8% level in alcohol (for many hours) may have sterilizing capability as well as 20% 0 aqueous formalin and formaldehyde with low temperature steam (75 C).


·E.coli and S.aureus cultures

·Nutrient agar


·0,5%  Zeption (1)

·5% formaldehyde

·70% ethyl alcohol


·Petri was divided into 3 parts and numbers were given to each part as 1 ,2 and 3.

·0,2 ml of E.coli was inoculated on Nutrient agar by spread plate technique

·E.coli was spreaded on plate

·Then sterile small spherical shaped filter paper was immersed 0,5 % zeption solution and the put on the number 1 on the plate

·Another filter paper was immersed in 5% formaldehyde and put on number 2 on plate

·The last fitler paper was immersed into 70% ethyl alcohol and then put on number 3 on plate

·The plate was incubated at 37°C for 24 hours

·The effectiveness of anticeptics was compared after incubation

Indication of effectiveness of anticeptics

No growth = +++

Poor growth = ++

Excellent growth = 0 (none)


1 = ++

2= +++



In this experiment we have examined the effectiveness of anticeptics.We have seen that the effectiveness of anticeptics are 2>1>3.It means that the effectiveness of formaldehyde on the growth of E.coli is greater than that of zeption and ethly alcohol.These anticeptics are low level anticeptics so they dont have a strong killing effect on microorganisms.In food industry,anticeptics and disinfectants can be used to sterilize the equipments and for the elimination of microorganisms.There are some physical disinfection methods used in industries such as 


Pasteurization for wine and dairies for milk (62+ C for 30 minutes) has been adapted for disinfecting laboratory and health care facilities heat labile instruments that might be damaged by some temperatures. This consists, essentially, of a washing process to remove 99+% of the organic matter and organisms followed by immersing into water at 60 C-65 C for at least 30 minutes.


Ultra-violet lights as it is used in laboratories and health care facilities may reduce the number of organisms to low level in the air and on surfaces but it is not a sterilizing process. It must be well engineered and installed very carefully to prevent burning of skin and eyes.


The filtration in the laboratory of fluids that are heat labile such as antibiotics, vitamins and other growth factors may be carried out with very fine pore membrane filters below 0.45 microns in diameter. These fluids should be checked for sterility by subculture before use.The HEPA filtration reduces the number of organisms but does not achieve real sterilization.