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Concernant la présentation orale.

La durée est parfaite (5:31 mins)

Attention Ă  la prononciation de certains mots comme "find", "yeast", "finally", "know", "swabs", "due to", "disturbing", et certains mots "transparents" comme "antimicrobial", "privatisation", "different", "compare",…

Il y a quelques erreurs comme "there is never colonies" =} "there are/were no colonies", ou "Not bacteria" =} "No bacteria "

N'oublie pas de bien prononcer le morphème –ed : "too concentrated"

et la phrase "the dye was permit the agar which means that the antibacterial gel…." est mal dite

"we carry out…." =} "we carried" out…"…car c'est une action au passĂ©, donc il faut utiliser le prĂ©tĂ©rit.

Il faut bien prononcer les "s" à la 3ème personne du singulier et après chaque mot au pluriel, exemple "colonies et 1970s**

C'est bien présenté et ton texte est bien écrit.

The antibacterial gel:


The history of antibacterial gel:

Walter Koller and Manfred Rotter published the first works measuring antimicrobial efficacy in the 1970s.
In 1976, William Griffith, at the Friborg hospital in Switzerland, formulated the hydro-alcoholic solution.
In 1995, Didier Pittet popularized the formulation and responded to privatization.
Since 1979, several studies have evaluated hand hygiene practices.From 2001, hydro-alcoholic solutions were promoted to fight against nosocomial diseases. As of 2009, various health prevention organizations recommend the use of hydroalcoholic solution as barrier behaviors in the prevention of the spread of germs during pandemic influenza crises.

The formula for the hydro-alcoholic solution chosen by the World Health Organization was developed by Didier Pittet. It is very easy to make your own hydro-alcoholic solution: all the components (alcohol, hydrogen peroxide, glycerin, water) are available over the counter in supermarkets. Hygiene and safety conditions must nevertheless be respected (clean containers, handling with gloves, safe storage).In 2020, the French government uses the formulation in a decree and gives a manufacturing procedure and storage advice.

More nowadays, with the current epidemic of Covid-19 the antibacterial gel is more and more in demand, that production to strongly increase.

Hydroalcoholic solutions are disinfectant solutions for the skin. They are used to ensure hand hygiene. They act by direct and mechanical contact (in friction) and are used without water.
The hydro-alcoholic solutions have bactericidal, virucidal and fungicidal properties, without cleaning effect. They should be applied to dry, unsullied hands.

The practice of hand hygiene by hydro-alcoholic friction has become a recommended procedure, this procedure is faster, more effective and better tolerated than washing with water and antiseptic soap. It improves users' compliance and enables them to comply with recommendations relating to good hygiene practices.

Background and problematic:

Hydro-alcoholic solutions have different properties without a cleaning effect. They should be applied to hands.
We know that numerous bacteria are present on the skin and mucous membranes of healthy subjects, they constitute the resident commensal flora. These actively participate in maintaining health.
Commensal bacteria are divided into 4 main flora (cutaneous, respiratory, genital and digestive).
The skin flora is variable in quality and quantity.
- The resident flora consists of potentially pathogenic Gram + germs, in significant quantities in the samples and present in the hair follicle.
-The transient flora is more varied and may include potentially pathogenic germs, coming from the digestive tract:
Enterobacteriaceae, Staphylococcus aureus….

We asked ourselves how the sensitivity of certain microorganisms to antibacterial gel is different?

To answer the problem, we carried out four manipulations. First of all, we have achieved cell viability to find out if the antibacterial gel is effective on yeasts. Then we used the antibiogram technique to compare the antibacterial gel with other product and conclude on the most effective product. Then we carried out a protocol on hand washing to determine the bacteria present on it and to compare the effectiveness of the gel to that of the soap. Finally we have MICs to know the minimum inhibitory quantity and to compare the gel to a disinfectant, we also did a CMB to finalize this manipulation.

One of the four manipulations:

I will present the protocol for the antibiogram.

 The principle of the antibiogram is to cultivate bacteria, and to apply a disc containing a product, in order to see what effects it plays on the targeted bacteria.
The goal of the antibiogram is to find a product that will be effective against a given infection.

To carry out this protocol we took 3 MH agars or we put using a swab of the bacterial suspension on the agars (suspension of E.coli, Candida Albican and S. aureus), then we put 5 risks sterile on each agar or we put antibacterial gel in different quantities (0.05mL-0.025mL-0.015mL-0.01mL), we also made a control disc or we put nothing on it. The suspension being too concentrated we had to redo the protocol in another test session.

At the next test session we diluted the bacterial suspensions to 1 / 10th and we chose to deposit on its three agar 5 sterile disc or we deposited 0.015mL of alcohol, antibacterial gel, disinfectant, bleach and sterile water, we also drop an Ampicillin disc. We also deposited on three other agars a disc containing 0.015 ml of an old gel and 5 disc of antibiotic (chloramphenol, rifampicin, streptomycin, oxolinic and amoxycylline).
We also wanted to be sure that the gel fit well in the chosen agar so we placed on a agar 2 sterile discs with 0.020 ml of gel mix either with red dye or with blue dye.

The results obtained for the 4 manipulations:

Cell viability: On the control, the cells are all alive because we did not put an antibacterial gel, on the test we observe 1111 dead cells and 0 living cells
So we can calculate the viability:
viability = number of living cells / total number of cells = 0/1111 = 0%
The cell viability is 0% so this means that no cell has resisted the antibacterial gel and therefore that the antibacterial gel is very effective against yeasts. We can therefore conclude that the antibacterial gel used is fungicidal.

Antibiogram: For the first test that we observe on our agars does not require any inhibition circle around the discs arranged on the agars. It can therefore be assumed that the gel is ineffective or that the bacteria are too concentrated. Due to the lack of dilution of the bacteria, we can conclude that the test did not work because the bacteria were too concentrated.
For the second test, we observe that the dye has permeated the agar, which means that the antibacterial gel works well with HD agar.


We observe that the antibacterial gel is effective with E.coli and S. aureus but that it does not work with C.albicans. We can observe that we had only the Oxolynic which is effective against yeasts. For S. aureus we observe that the most effective remains the antibacterial gel but that amoxycylline also remains as effective. And for E.coli we can say that alcohol and bleach are more effective than antibacterial gel but E.coli is still sensitive to antibacterial gel. We also observe that the old gel is not effective.

We can therefore affirm that this antibacterial gel is not effective with yeasts but it is indeed bactericidal and the bacterium S. aureus is more sensitive to the gel than the bacterium E.coli.

Hand washing: To begin with, we made control plates or we observed only one colony on the Drigalski, few colony on the Chapman and numerous colony on the Sabouraud and the PCA.
We observe on Drigalski agars that there is never a colony except one on agar where we put our unwashed hand we can say that there is no gram - on the commensal skin flora and that gel and soap destroy all the gram - present on our hands.
The agars where we put our hands washed 30 seconds with antibacterial gel contain no colonies which means that the gel is effective when we wash our hands for 30 seconds while the agars where we washed our hands with gel antibacterial for 1 minute contains about ten colonies on all agars except on the Drigalski where there is none which means that it is more effective to clean your hands by gel friction for 30 seconds, the rubbing hands longer could bring bacteria back to your hands.

On agars where we have washed our hands with soap for 30 seconds we observe colonies in average quantity which are always more numerous than when we wash our hands with gel, the gel is therefore more effective. On the agars where we washed our hands for 1 minute with soap there is no longer a colony on the Sabouraud and on Chapman we observe a small amount of colony and on the PCA we observe a very large amount colony, which means that washing your hands for 30 seconds with soap is less effective than washing them for 1 minute.

We can conclude that the antibacterial gel is more effective than soap regardless of the washing time.

MIC: To start, we did a CMI with the antibacterial gel or we observed that all the tubes were cloudy and that the result was therefore not usable. Subsequently, we redid this MIC but with a different witness (with gel and without bacteria), we then noticed that this witness was cloudy, so we concluded that it was the gel that disturbed the environment.


So we have to carry out CMB to be able to know which tube the bacteria are still alive. We have therefore seen that for E. coli there is no bacteria from tube 1 to tube 2 which means that the minimum inhibitory concentration for E. coli is 0.25 mg / ml, for S. aureus it there is no bacteria on tube 1 which means that the minimum inhibitory concentration for S. aureus is 0.5 mg / ml and for C. albicans we observe that the last tube without colony is tube 2 which means that the minimum inhibitory concentration for C.albicans is 0.25 mg / ml.

I can therefore conclude from this manipulation that the gel is as effective with gram - (E.coli), as with yeast and gram + (S. aureus).


With all my results I can therefore say that according to the different bacteria the antibacterial gel will not act in the same way, knowing that the gel is used on the hands, it was therefore designed to eliminate the bacteria contained on the hands and on the commensal flor. But on the hands, we have very little gram - which explains why the gel is less effective on the gram - (E. coli) than on the gram + (S. aureus) and the yeast (C.albicans) as we can see it in our previous experience.

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