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Alcohols tend to be bactericidal and fungicidal, but may also be viricidal for enveloped viruses only. Although alcohols are not sporicidal, they do inhibit the processes of sporulation and germination. Alcohols are volatile and dry quickly, but they may also cause skin irritation because they dehydrate the skin at the site of application. One common clinical use of alcohols is swabbing the skin for degerming before needle injection. Alcohols also are the active ingredients in instant hand sanitizer s, which have gained popularity in recent years. The alcohol in these hand sanitizers works both by denaturing proteins and by disrupting the microbial cell membrane, but will not work effectively in the presence of visible dirt.

Last, alcohols are used to make tincture s with other antiseptics, such as the iodine tinctures discussed previously in this chapter. All in all, alcohols are inexpensive and quite effective for the disinfection of a broad range of vegetative microbes. However, one disadvantage of alcohols is their high volatility, limiting their effectiveness to immediately after application.

a) Ethyl alcohol has 2 C’s and an OH.  B) Isopropyl alcohol has 3 C’s and an OH.
(a) Ethyl alcohol, the intoxicating ingredient found in alcoholic drinks, is also used commonly as a disinfectant. (b) Isopropyl alcohol, also called rubbing alcohol, has a related molecular structure and is another commonly used disinfectant. (credit a photo: modification of work by D Coetzee; credit b photo: modification of work by Craig Spurrier)
  • Name at least three advantages of alcohols as disinfectants.
  • Describe several specific applications of alcohols used in disinfectant products.


Surface-active agents, or surfactants , are a group of chemical compounds that lower the surface tension of water. Surfactants are the major ingredients in soaps and detergents . Soaps are salts of long-chain fatty acids and have both polar and nonpolar regions, allowing them to interact with polar and nonpolar regions in other molecules ( [link] ). They can interact with nonpolar oils and grease to create emulsions in water, loosening and lifting away dirt and microbes from surfaces and skin. Soaps do not kill or inhibit microbial growth and so are not considered antiseptics or disinfectants. However, proper use of soaps mechanically carries away microorganisms, effectively degerming a surface. Some soaps contain added bacteriostatic agents such as triclocarban or cloflucarban , compounds structurally related to triclosan, that introduce antiseptic or disinfectant properties to the soaps.

A chemical structure with a long carbon chain and two oxygens at one end. The end with the oxygens is the hydrophobic head which shuns hydrocarbon-like substances but is attracted to water molecules. Thi sis the anionic portion of the molecule. The long carbon chains are the hydrophilic tail which shuns water but is attracted to oily greasy hydrocarbon-like substances.
Soaps are the salts (sodium salt in the illustration) of fatty acids and have the ability to emulsify lipids, fats, and oils by interacting with water through their hydrophilic heads and with the lipid at their hydrophobic tails.

Soaps, however, often form films that are difficult to rinse away, especially in hard water, which contains high concentrations of calcium and magnesium mineral salts. Detergents contain synthetic surfactant molecules with both polar and nonpolar regions that have strong cleansing activity but are more soluble, even in hard water, and, therefore, leave behind no soapy deposits. Anionic detergents , such as those used for laundry, have a negatively charged anion at one end attached to a long hydrophobic chain, whereas cationic detergents have a positively charged cation instead. Cationic detergents include an important class of disinfectants and antiseptics called the quaternary ammonium salts (quats) , named for the characteristic quaternary nitrogen atom that confers the positive charge ( [link] ). Overall, quats have properties similar to phospholipids, having hydrophilic and hydrophobic ends. As such, quats have the ability to insert into the bacterial phospholipid bilayer and disrupt membrane integrity. The cationic charge of quats appears to confer their antimicrobial properties, which are diminished when neutralized. Quats have several useful properties. They are stable, nontoxic, inexpensive, colorless, odorless, and tasteless. They tend to be bactericidal by disrupting membranes. They are also active against fungi, protozoans, and enveloped viruses, but endospores are unaffected. In clinical settings, they may be used as antiseptics or to disinfect surfaces. Mixtures of quats are also commonly found in household cleaners and disinfectants, including many current formulations of Lysol brand products, which contain benzalkonium chlorides as the active ingredients. Benzalkonium chlorides, along with the quat cetylpyrimidine chloride , are also found in products such as skin antiseptics, oral rinses, and mouthwashes.

Questions & Answers

what is parasite
Abdirizack Reply
designing of aseptic area
Aashish Reply
I don't know
what is rickettsia
what is microbiology
Is the science that works with microorganisms.
richettsa is small microorganisms that cause disease in human like typhus; they are like viruses that can grow only inside living cells, they're transmitted by mites, ticks or lices.
what is plasmid?
plasmid is extra chromosomal body present in bacteria...which have additional genetic functions example... antibiotic resistance genes....etc etc
state the theory of spontaneous generation of micro oranisms and germ theory of disease
what are the advantages of high note numerical aperture
Genius Reply
list if non flagellated pritozoa
Mepung Reply
Can someone that's understanding of the Kreb Cycle please explain & breakdown it down to me in the simplest way without giving me the dictionary version or Google version. Basically in there own words of knowledge....!
please can someone help explain positive and negative feedback in simple term
negative feedback is the arresting of reaction or reverse of the reaction according to the response and postive feed back is the direct response without reversing or arresting a reaction.
pls can someone explained Kinney stone in memorising in shot time
what tyoebif microorganism will be killed by antibiotic trwatmeant
Mary Reply
I don't really don't understand aerobic respiration anaerobic respiration and fermentation. Can someone explain & breakdown this in the simplest way please.
Anaerobic Respiration in which foodstuffs are partially oxidized, with the release of chemical energy, in a process not involving atmospheric oxygen, such as alcoholic fermentation, in which one of the end products is ethanol.
aerobic respiration A type of respiration in which foodstuffs are completely oxidized to carbon dioxide and water, with the release of chemical energy, in a process requiring atmospheric oxygen.
please can someone explain what pseudomonas species and biofilm is?
Fermentation is the growth of cells or microorganisms in bioreactors (fermenters) to synthesize special products. Fermentation in biochemistry refers to the biodegradation of carbon compounds by cells or organisms under anaerobic (lack of oxygen) conditions.
Please under which conditions does pathogens become established in the human tissues and can cause diseases
please the life cycle of plasmodium parasite
who is John Needham
Mary Reply
John Needham is one of the researcher in microbiology. He also experimented when scientists did not believe animals could arise spontaneously ,but did believe microbes could.
okay is he late
by the way what are the list of courses offered by a newly admitted student for microbiology
Needham's experiments with beef gravy and infusions of plants material reinforced this idea.
what drugs are given to a person with Otis nerve problem(ear problem)
Gum Reply
good morning to you all.
Muhammad Reply
Dr.A.K.S.P.G. college Akbarpur Ambedkar Nagar
Shailesh Vishwakarma BSc 1st year
differentiate between eukaryotes en prikaryotes
eukaryotes are organisms with complex cellular structure(presence of nucleus and mitochondrial) like plants and animals whilst prokaryotes are organisms with simple cellular structure (absence of nucleus, mitochondrial) like arthropods.
hello sir
I am Pankaj from bihar
I am study in NDRI karnal in btech in dairy
I am Pankaj from bihar
thanks am studying biomedical sciences in zambia.chikankata
Am a studying Disease Control in Ghana(kintampo)
I'm studying Environmental health in Zimbabwe 🇿🇼
am Joyce mwale studying nursing in Lusaka Zambia
hi pankaj
hi frds iam from India
IAM studying degree (micro biology)
Hi I am microbiologist
Hi friends I'm from Nigeria studying Microbiology
i am biotechnologist from pakistan
hi feds iam from india
hy frnds am from Uganda
am studying nursing/midwifery n kampala
I'm Gum Joseph Kakuu from Ghana,I'm studying RGN in nursing Jirapa.
I'm Hellen from Kenya studying applied biology
I live in india
am studying biotechnology
am maryjoy uwaoma from Nigeria,I am studying microbiology in NSUKKA NIGERIA
Nice meeting You people hear
thanks you.
can someone in there own words in the simplest way breakdown what aerobic respiration anaerobic respiration and fermentation means please and not from the dictionary version...!
what are the cultivation and identification of microorganisms
Algel Reply
ransport media.basic culture media.enriched media..differential media .indetification media
algel th above are some v th basic medias for bacterial growth
factors that can Prone the host to get disease
Linda Reply
what are the factors that prones host to get disease
Not sure about it, can you tell us Linda?
please I want to know the factors that prones host to get disease
please Linda we have internal and external factors. internal factors are within our body cavities.eg mother having TB giving it to her child,and the others. external factors are within our surrounding environment which include our daily activities(bathing, buying food and the others)
I don't understand aerobic respiration anaerobic respiration and fermentation. Can someone that do give me a short & simple breakdown.
pliz kisha ..aerobic respiration is th typ v repiration whre organisms use oxgyen for survival while anaerobic respiration is whre organisms survive without oxgyen at all.these use carbondioxide
Guys pls answer me this question fast... What are the purpose of infection prevention in 50 words..
The purpose of infection and prevention is a scientific approach and practical solution designed to prevent harm cause by infection to Pt and health worker
what is the sequence of kingdom concept?
isha Reply
what is immunity
what are the classification and identification of microorganisms
whats anatomy
and physiology
anatomy is the study of the human structure
physiolog is the study of the human body function
Anatomy and physiology is the study of the human body parts and their functions.
who's the father of Microbiology
The definition you gave is not for the two
leeuwenhoek is the real father of microbiology
anatomy is the study of the structure and relationship between body part while Physiolog is the study of the function of body part
thats real definition
I am sure about Louis pasteur been the real father of microbiology
microbiology father is marcelo
sorry the father is Anthony Van Leeuwenhoek
The father is Marcello Malpighi
Anatomy and physiology is the study of the body structures and how they relate to each other

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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