Liliana Junqueira de P. Donatelli

Frequently asked questions

1-Sterilization Control, how is it done?

Monitoring is nothing more than controlling the quality of the sterilization. It is essential to be done independently of the method chosen. Sterilization failures may occur due to some mistakes by the:

• operator;

• equipment;

• installation;

• multiple faults;

The monitoring purpose is mainly to detect these faults and reduce them as much as possible.

The sterilization monitoring consists in the following stages:

Physical Monitoring

The physical monitoring in autoclaves like the ones manufactured by Cristófoli is made in the dentist’s own office by the operator, it consists in verifying if the autoclave reaches the physical parameters of time/temperature and pressure according to the cycle, model and the instruction manual that accompanies each equipment. If that doesn’t happen the technical assistance must be contacted. In case of doubt, contact our CSD – Customer Service Department through the e-mail: cristofoli@cristofoli.com

Chemical Monitoring

It is done by using chemical indicators.

Class 1*: Passage indicators are frequently found in autoclave tapes, they indicate if a determined package went through the process, however, it does not guarantee the package has been sterilized. These indicators must be used externally, in all packages.

Class 4*: There are some multi-parametric chemical indicators to be used in each package. They show that the steam and heat have penetrated the package but these also do not guarantee that the sterilization was really achieved.

Class 5*: Chemical integrator to be used inside the packages to be sterilized in steam autoclaves under worldly known and accepted parameters. It offers good reliability, however, if the temperature goes above 140°C, the indicator approves the cycle independently the presence of seam, that’s shows its limitations.

Class 6*: Emulators for specific temperature, 121º C or 134º C, specific and predetermined times. The Browne Emulators (5,3 min 134°C), were tested and approved at Cristófoli for the autoclaves Vitale 12/21, Vitale Plus 12/21 and Plena A. They should be used regularly. Providing immediate results, they are practical and easy to use or store.

They are recommended to be used at least on the first sterilization cycle of each work day. They present great reliability and certify that the cycle achieved all the conditions (enough exposure under specific temperature in the presence of steam) so that the sterilization have occurred.

*(according to the ISO 11140).

Biological Monitoring

It is the most reliable monitoring, it is done with technically prepared microorganisms (biological indicators) to demonstrate the sterilization.

2. What is a biological indicator?

They are tests that come in plastic tubes with a steam permeable lid, inside there’s a paper strip impregnated with a known population of spores, separated from growth medium (purple liquid), by a glass ampoule.

The spores used are the Geobacillus stearotermophilus, which are highly resistant to the humid heat and are not pathogenic. They are used as a challenge, once they are eliminated, all other spores and vegetative forms will also be.

3. How to make the biological test in my autoclave?

The test is put inside a package which will be submitted to a sterilization cycle in the autoclave. Hospitals generally do the test in the first cycle in the morning, the package is put in the oldest spot inside the chamber, lowest tray near the drain. For the Cristófoli Autoclaves models Vitale 12 and 21 liters, put the indicator in the front part of the top tray (close to the door), for the Lister (vertical model) in the center of the chamber, these are the coldest spots for these models due to the position of the heating elements.

When the cycle is over, the package must be opened and the indicator retrieved, wait 15 minutes for it to cool down and lose pressure. Squeeze the plastic flask (activation), this will break the glass ampoule inside and will expose the spores to the growth medium. The test indicator sterilized is then put in the incubator (get to know the Cristófoli Min-incubator) along with a “control” indicator that was not sterilized, only activated by breaking the glass ampoule (see use instructions in the indicators box or Mini-incubator instruction manual). the purpose is to test not only the spores viability but also if the incubator is working properly. The expected result is that the “control” test change to from purple to yellow. This color change occurs due to the alteration of the pH of the solution triggered by the microbial activity. The test indicator should not change color at all, it’s expected that the microorganisms have been destroyed during the autoclave sterilization cycle. The final reading of the result is done after 24 to 48 hours of the indicators incubation.

4. How often do I have to use them?

The recommendation of the Brazilian Health Ministry and Sanitary Surveillance Departments is that the biological indicators be used on a weekly basis. Several organizations that deal with hospital infection control recommend their use with all loads containing implantable items. Our recommendations is a weekly biological control and at least one chemical emulator class 6 and one process test in the first cycle on a daily basis.

5. Is autoclave tape the same thing as a biological indicator?

No, autoclave tape is a chemical indicator, (process indicator or class 1), it only shows that the package went through the sterilization process, it does not prove the items are sterile.

6. Are the chemical indicators reliable?

The integrators and the emulators are the most reliable chemical indicators, they use several parameters simultaneously. They are very accurate, indicators class 6 only change colors when 95% of the cycle is according to sterilization standards. Although they do not allow counterproof like the biological indicators, they offer reliability regarding the cycle effectiveness.

7. Why use so many controls?

The ideal would be to use biological indicators for each package, but that would be very expensive. Besides, the results would be available only after 24 hours in average. By using all these types of controls we get to monitor the sterilization process faster and with a lower cost while detecting any flaw that may occur. It doesn’t matter how good or reliable the sterilization equipment may be, it must be monitored and go through routine technical maintenance. One can only know if it is working properly in case it is regularly monitored.

Picture a dental implant surgeon who finds out a flaw in his autoclave after his/her patient starts loosing implants! What would be the cost in a situation like that?

Prevention is the best option to control infections.

For your safety and our quality control, the physical tests are made initially at Cristófoli through the validation of the autoclaves, this is done by specialized engineering companies to assure the equipment reach the time, temperature and pressure, according to its purpose (sterilization). Quality control tests are carried out on the components received, after the autoclave is ready, sterilization cycles with an emulator class 6 are run while the physical parameters are monitored. The emulator used is included in the documentation of each piece of equipment. Besides, each autoclave batch produced is monitored with biological indicators.

In order to facilitate the monitorization in dental offices, Cristófoli has launched a second generation incubator for biological indicators as well as practical 10-unit packs of biological indicators.

In case of doubts or suggestions, please contact us.

Liliana Junqueira de P. Donatelli
Biologist CRBio 18469/01-D
Master in Public Health- UNESP – Botucatu Medicine University
Cristófoli Biosafety Consultant
e-mail- consultoria@cristofoli.com
lilianadonatelli@uol.com.br