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A) A diagram of cetylpyridinum – a ring with 5 carbons and a nitrogen. The nitrogen is attached to a long carbon chain. Chemical structure of Benzalkonium – a six carbon ring. One carbon is attached to a carbon that is attached to a nitrogen which is attached to a long carbon chain. B) An image of surfactant molecules entering a membrane and breaking the membrane apart.
(a) Two common quats are benzylalkonium chloride and cetylpyrimidine chloride. Note the hydrophobic nonpolar carbon chain at one end and the nitrogen-containing cationic component at the other end. (b) Quats are able to infiltrate the phospholipid plasma membranes of bacterial cells and disrupt their integrity, leading to death of the cell.
  • Why are soaps not considered disinfectants?

Handwashing the right way

Handwashing is critical for public health and should be emphasized in a clinical setting. For the general public, the CDC recommends handwashing before, during, and after food handling; before eating; before and after interacting with someone who is ill; before and after treating a wound; after using the toilet or changing diapers; after coughing, sneezing, or blowing the nose; after handling garbage; and after interacting with an animal, its feed, or its waste. [link] illustrates the five steps of proper handwashing recommended by the CDC.

Handwashing is even more important for health-care workers, who should wash their hands thoroughly between every patient contact, after the removal of gloves, after contact with bodily fluids and potentially infectious fomites, and before and after assisting a surgeon with invasive procedures. Even with the use of proper surgical attire, including gloves, scrubbing for surgery is more involved than routine handwashing. The goal of surgical scrubbing is to reduce the normal microbiota on the skin’s surface to prevent the introduction of these microbes into a patient’s surgical wounds.

There is no single widely accepted protocol for surgical scrubbing. Protocols for length of time spent scrubbing may depend on the antimicrobial used; health-care workers should always check the manufacturer’s recommendations. According to the Association of Surgical Technologists (AST), surgical scrubs may be performed with or without the use of brushes ( [link] ).

a) CDC handwashing recommendations for the general public. 1 – wet your hands with clean, running water (warm or cold). Turn off the tap and apply soap. 2 – Lather your hands by rubbing them together with the soap. Be sure to lather the backs of your hands, between your fingers and under your nails. 3 – Scrub your hands for at least 20 seconds. Need a timer? Hum the “Happy birthday” song from beginning to end twice. 4 – Rinse your hands well under clean, running water. 5 – Dry your hands using a clean towel or air-dry them. B) A photo of a person washing their hands.
(a) The CDC recommends five steps as part of typical handwashing for the general public. (b) Surgical scrubbing is more extensive, requiring scrubbing starting from the fingertips, extending to the hands and forearms, and then up beyond the elbows, as shown here. (credit a: modification of work by World Health Organization)


Bisbiguanides were first synthesized in the 20th century and are cationic (positively charged) molecules known for their antiseptic properties ( [link] ). One important bisbiguanide antiseptic is chlorhexidine . It has broad-spectrum activity against yeasts, gram-positive bacteria, and gram-negative bacteria, with the exception of Pseudomonas aeruginosa , which may develop resistance on repeated exposure. L. Thomas et al. “Development of Resistance to Chlorhexidine Diacetate in Pseudomonas aeruginosa and the Effect of a ‘Residual’ Concentration.” Journal of Hospital Infection 46 no. 4 (2000):297–303. Chlorhexidine disrupts cell membranes and is bacteriostatic at lower concentrations or bactericidal at higher concentrations, in which it actually causes the cells’ cytoplasmic contents to congeal. It also has activity against enveloped viruses. However, chlorhexidine is poorly effective against Mycobacterium tuberculosis and nonenveloped viruses, and it is not sporicidal. Chlorhexidine is typically used in the clinical setting as a surgical scrub and for other handwashing needs for medical personnel, as well as for topical antisepsis for patients before surgery or needle injection. It is more persistent than iodophors, providing long-lasting antimicrobial activity. Chlorhexidine solutions may also be used as oral rinses after oral procedures or to treat gingivitis. Another bisbiguanide, alexidine , is gaining popularity as a surgical scrub and an oral rinse because it acts faster than chlorhexidine.

Questions & Answers

what is mutation
Cynthia Reply
alteration in genetic makeup
Hi, I'm new here. I'm Bello Abdul Hakeem from Nigeria.
welcome on board
Thanks brother I'm an undergraduate. I hope to study for MBBS.
pls guys help me out
what is limitation of plate
limitation of plate load test . there are some that should be considered while performing load test which are given below, this test is usually performed on relatively similar plate ,usually 1 or 2 square foot area the reason is that the plate of greater are the economically not feasible
Mechanism of bacterial pathogenicity
rashida Reply
write a short note on Algea
najaatu Reply
green minutes plants organisms that are produced in turf.
Algae is a kind of a photosynthetic organism, which is usually grown in the moist areas. These are usually the simple plants that grow near to the water bodies. It contains a kind of chlorophyll pigments that act as a primary coloring agent.
they are eukaryotic and most lived in fresh water. they are photosynthetic that's, they contain chlorophyll and store starch in discrete chloroplast.
are bacteria important to man
just Reply
yes, depending on the type of bacteria .eg the normal florals, the latic acid batteries etc are important to man
I mean latic acid bacterial
I don't understand this topic
Jane Reply
what topic is that
sahi kon hai bhosri ke
saurabh Reply
define metabolism of carbohydrates with example
Thavasi Reply
what is sterilization a
the process of keep equipment free from bacteria
is it only bacteria?
no undesirable fungi and contamination also.
what is streak plate method
what is the biofilm
metabolism is the sum of all the biochemical reaction required for energy generation and use of that energy to synthesize cell materials from small molecules in environment.
what are granulocytes
Shawnitta Reply
granulocytes are type of WBCs which contains granules in the cytoplasm
what is mutation
it is the interchange of genes from their normal sequence
is an heritable change of the base-pair sequence of genetic material
suitable example for prokaryotes
Suvetha Reply
one of the possible early sources of energy was
uv radiation and lighting
e coli is the example of prokaryotes
archaea too
which is the specific virus causing typhoid
Jeremiah Reply
it's caused by a virulent bacteria called Salmonella Typhi
write the life cycle of HIV
Firomsa Reply
describe the internal and external structure of prokaryotic cell in terms of there appearance and functions
Lenia Reply
compare and contrast similar structures found in prokaryotic and eukaryotic cells
control of microorganisms
what is sterilization
how can a doctor treat a person affected by endospore forming bacteria in his/her wound?
Mambo Reply
define disinfectant
the process of killing
the process of killing microorganisms

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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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