Sterilization means the use of a physical or chemical
procedure to destroy all microbial life including
resistant bacterial endospores.
It causes denaturation of
proteins, nucleic acids and
components of cellular
The importance of sterilization :
- reduction of number of deaths
- improvement of surgical
- reduction of epidemic diseases
- improvement of health conditions
Sterility assurance level (SAL) is the probability of a
single unit being non-sterile after it has been
subjected to sterilization:
for tools operating on internal tissue (surgical
tools, implantable devices);
for tools operating on external tissue.
N = number of microorganisms
N0 = initial number of microorganisms
T = time
D = decay constant
8. Sterilization: physical methods
Gamma Radiation (usually Cobalt-60 or caesium-137)
Commonly used in biomedical device sterilization, it
does not produce radioactivity on the objects.
Very efficient but
9. Sterilization: physical methods
UV sterilization (wl = 230-280 nm, typically 254 nm)
Mainly used to sterilize water, air fluxes and surfaces.
Cheap and fast
system, but no
and not usable with
12. Formaldehyde is used to preserve
anatomic specimens and to
prepare viral vaccines.
Sterilization: chemical methods
Glutaraldehyde and Formaldehyde: separately and in
solution. Method expensive and of low durability and
taking long time (>20h).
Glutaraldehyde is used for medical
devices such as endoscopes;
objects sterilized by it can not be
13. Sterilization: chemical methods
Hydrogen Peroxide is a strong oxidant.
It is used for heat
disinfecting soft contact
lenses and endoscopes.
Peracetic acid shows a rapid
action against all microorganisms (t < 30min).
It is used for surgical and dental instruments.
16. Sterilization: regulations &
National regulation agencies
International regulation agencies for regulatory
harmonization in a specific area
International regulation agencies for global
WHO, Harmonization Task Force (GHTF) , International Medical
Devices Regulatory Forum (IMDRF)
17. Sterilization: regulations &
Goals: creating occasions to exchange information
about regulatory on medicine and biomedical fields to
reach a harmonization system.
In their sites there are sections with documentation
www.amrh.org & www.pahwp.org
22. Sterilization: regulations &
Typical ISO standard rule structure:
I. Definition of application field
II. Definition of technical terms used in the
III. Regulatory references
IV. Technical regulations
V. Technical tables and appendixes