This document discusses sterilization methods for infection control in medical offices. It states that instrument sterilization is an important part of infection control. The main sterilization methods discussed are steam under pressure, dry heat, chemical vapor, and ethylene oxide gas. It provides details on cleaning, packaging, and monitoring instruments to ensure effective sterilization. Biological indicators that test for microbial kill are emphasized as the ultimate criteria for verifying sterilization.

1. STERILIZATION
METHODS

2. INFECTION CONTROL IN THE MEDICAL OFFICE
Infection control has assumed a greater role in medicine
and dentistry than ever before. The Centers for Disease
Control (CDC) has issued guidelines for infection
control in the the medical, surgical, dental, or podiatric
office or clinic. Instrument sterilization is one of the
most important parts of office infection control. The
cardinal rule of infection control is "Do not disinfect
when you can sterilize." The approach is to sterilize all
reusable instruments contaminated with blood, or that
have penetrated tissue or touched bone (universal
sterilization). This is better than to sterilize some
instruments and disinfect others and is the safest
approach to prevent spreading disease to patients.

3. STERILIZATION IS A PROCESS INTENDED TO KILL
ALL MICROORGANISMS AND IS THE HIGHEST
LEVEL OF MICROBIAL KILL THAT CAN BE
ACHIEVED.
A process cannot be called a
sterilization process unless it
has been shown to be capable
of killing high numbers of
bacterial spores, the most
difficult of microorganisms to
kill. The CDC views steam
under pressure, dry
heat, chemical vapor and
ethylene oxide gas as
appropriate sterilization
methods.

4. To assure effective microbial kill with
minimal instrument damage and
protection to the staff performing the
procedures, several steps must be
performed:
presoaking, cleaning, corrosion
control and
lubrication, packaging, sterilization
and sterilization monitoring.

5. PRESOAKING
Usually, material allowed to dry on an instrument is
more difficult to remove. If cleaning is delayed, keep the
instruments wet in a holding solution. This may be a
mild detergent, or an instrument disinfectant or sterilant.
Do not presoak for more than a few hours, as the longer
instruments remain wet, the greater the chances for
corrosion of non-stainless items.Wear heavy utility
gloves when handling contaminated instruments and
mixing chemical solutions. Wear protective eyewear, a
mask and protective clothing to prevent contamination
from splashing of the solutions.

6. CLEANING
The CDC and the Food and Drug Administration (FDA) state that
"Cleaning is the basic first step of all decontamination. You always
need to clean before you disinfect or sterilize." Patient debris and
body fluids must be removed from the instruments before
sterilization. Debris can insulate microorganisms from the sterilizing
agent, preventing direct contact and inactivation.Two approaches to
instrument cleaning are hand-scrubbing and ultrasonic cleaning.
Hand-scrubbing is directly contrary to one of the principles of
infection control (reduce direct contact with contaminated surfaces
as much as possible). Handscrubbing of contaminated instruments
can create spatter and aerosols and increase the chances for an
instrument puncture.When hand-scrubbing, minimize spattering by
scrubbing while the instruments are submerged and then rinse
thoroughly under tap water and dry. Drying is very important for
instruments that will be sterilized in an unsaturated chemical vapor
or in a dry heat sterilizer.

7. ULTRASONIC CLEANING
Ultrasonic cleaning is recommended in place of hand-
scrubbing in order to reduce direct staff contact with
contaminated instruments. Presoaked or other instruments
should be rinsed and then placed in a cleaning basket and
submerged in the cleaning solution. For best results,
follow the directions from the manufacturer of the
ultrasonic cleaner. Place the cover on the cleaner and
clean for 6 to 10 minutes or until no debris is visible on
the instruments.Hold the cleaning basket of instruments
under tap water and rinse thoroughly. Ultrasonic cleaners
cannot be considered sterilizers. Thus, the cleaned
instruments are still contaminated. The cleaning solution
should be drained and discarded at least daily and the
cleaner chamber rinsed and disinfected at the end of the
day.

8. CORROSION CONTROL AND LUBRICATION
Always dry cleaned instruments to be processed
through a dry heat, chemical vapor or ethylene
oxide gas sterilizer or packaged in a paper wrap.
Drying reduces the chances of corrosion and
rupture of the paper wrap. A rust inhibitor can be
applied to non-stainless items to be processed
through the steam autoclave.

9. PACKAGING
Instruments should be pre-packaged before
processing through a sterilizer so they will be
protected from contamination after sterilization.
Use packaging material designed for the method
of sterilization to be used. Avoid thin paper bags
that allow sharp instruments to protrude.
Unwrapping pre packaged instruments at chair
side in front of the patient can help build patient
confidence about the cleanliness of the office.

10. STERILIZATION TIME
Sterilization fails when the sterilizing agent--
steam, hot air, or chemical vapor--does not
contact the processed items for the appropriate
length of time. Sterilization requires varying
degrees of time, depending on the
load, arrangement, packaging material, and
temperature as well as the type of sterilizing
agent. Follow the manufacturer's direction and
define the proper sterilizing time by results of
routine spore-testing.

11. STERILIZATION MONITORING
Sterilization can be monitored by chemical
indicators (color change) but effectiveness
cannot. Chemical indicators are strips, tapes and
markings on bags and pouches that change color
or physical form after exposure to the sterilizing
agent. They immediately indicate that the items
have been processed through the sterilizer and
have been exposed to heat, steam or chemical
vapor. Since chemical indicators do not analyze
for microbial kill, they should be used in
conjunction with, but never as a replacement for
spore-testing, which provides the main guarantee
of sterilization.

12. BIOLOGICAL INDICATORS
Biological indicators are the ultimate criteria for
monitoring sterilization. The CDC states the
proper functioning of sterilization cycles should
be verified by the periodic use (at least weekly)
of biologic indicators (i.e., spore tests). OSHA
recommends following CDC guidelines for
standard sterilization procedures.

13. Proper spore-testing in the medical, surgical, dental, or
podiatric office or clinic involves placing the appropriate
type of biological indicator (spore test) inside a normal
instrument pack, bag, or tray. Biological indicators
operate on the premise that destruction of heat-resistant
spores implies destruction of viruses and bacteria, which
are more easily inactivated. The biological indicator is
included in a sterilization load and subjected to the cycle.
It is then incubated in a nutrient medium and evaluated.It
is the responsibility of each the
medical, surgical, dental, or podiatric office or clinic to
assure their staff and patients that products at point-of-
use are sterile. Appropriate records should be kept to
document sterilization verification.

14. References
(1.) Department of Labor, Occupational Safety and Health
Administration. 29CFR Part 1910.1030, Occupational
exposure to bloodborne pathogens; final rule. Fed Reg
1991,56:64004-182.
(2.) Infection control guidelines. Denver: Office
Sterilization and Asepsis Procedures Research
Foundation; 1992.
(3.) Office Sterilization and Asepsis Procedures Research
Foundation. Infection control guidelines. Denver; 1991.
(4.) Centers for Disease Control. Recommended Infection-
Control Practices. MMWR 1993; 42:1-10.

15. A. METHODS OF STERILIZATION

16. 1. PHYSICAL METHODS
Steam Thermal
Definition -- a self-locking apparatus
for the sterilization of material by
means of steam under pressure.
 Settings for general wrapped
items:
Temp. - 250oF Pressure -
Time -- 30 min Setting -- Fast
Exhaust & Dry

17.  Settings for bottled solutions:
Always vent bottles to avoid bursting!
Temp. - 250oF Pressure - 20 PSI
Time -- 30 min Setting -- Slow Exhaust
 Setting for "Flashing" an unwrapped instrument:
Temp. - 270oF Pressure
Time -- 4-7 Min Setting -- Fast Exhaust
Notes -- The above are general steam autoclave settings.
Different models may operate with varying settings. Always
refer to the appliance literature before operating a new piece
of equipment.
Radiation
 Use on materials that cannot be sterilized by heat or chemicals
 Radiant energy destroys microorganisms
Filtration -- is a method utilizing filters capable of screening out
microorganisms

18. 2. CHEMICAL METHODS

19.  Ethylene Oxide Gas
 Colorless gas at room temperature
 Odor similar to ether
 Very toxic and irritating to skin and mucous membranes
 Microorganism destruction is caused by a chemical
reaction
 Materials sterilized need to be aerated in well ventilated
room or placed in an aerator.
 Length of time required for aeration depends on items
sterilized.
 Effective sterilization is dependent on concentration of
gas, exposure time, temperature, and relative humidity
 Hazardous chemical, use great care

20.  Cold Sterilization
Instruments should be completely dry before soaking to
prevent dilution
Instrument soaking solution - 10-20 minute emersion
only disinfects
Incomplete destruction of spores, unless soak is for 10
hours
Examples: Instrument Germicide (Phenol and Ethyl
alcohol), CidexTM (Glutaraldehyde)
Most require thorough rinsing before using instrument
Contact time required varies with product used

21. B. STERILIZATION SHELF LIFE OF
PACKAGED SUPPLIES

22. 2. TWO (2) PACKAGING METHODS ARE STERILE
FOR UP TO SIX (6) MONTHS:
 MonarchR Instrument Canisters -- Special box system with
single use filters for use in steam autoclaves
 Sterility Maintenance Covers -- Sealable plastic covers to place
over freshly autoclaved and cooled packs to extend shelf life by
diminishing air penetration

23. 1. THE FOLLOWING WRAPPED ITEMS, IF
CAREFULLY MAINTAINED, ARE STERILE
FOR UP TO ONE (1) MONTH:
 Double cloth wrapped instruments
 Double paper wrapped instruments
 Inexpensive peel pouches for gauze sponges
 NalgeneR saline bottles

24. 3. HEAT SEALED PACKAGES COMMERCIALLY
PREPARED IN TUBE OR PEEL POUCH FORM MAY BE
CONSIDERED STERILE FOR UP TO ONE (1) YEAR.
C. Sterility Check List

25. BEFORE ASSUMING A PACK IS STERILE, ALWAYS
EVALUATE THE FOLLOWING BEFORE OPENING THE
PACK:
Expiration or sterilization date
Indicator color change
General condition of wrapper and how it
had been stored
Always check for holes or moisture
damage