Cleaning/decontamination, disinfection, and sterilization

1
Cleaning/decontamination, disinfection, and
sterilization

• Kumthorn Malathum, MD
• Chair, ICC, Ramathibodi Hospital

2
Scope

• Cleaning/decontamination, disinfection, and
  sterilization of medical devices
• Environmental cleaning
• Routine floor, bed rail, etc.
• MDR bacteria
• Respiratory pathogens (virus, mycobacteria)

3
Virulence is not correlated with the ease to be
destroyed!
Certain enveloped (lipophilic) viruses (e.g.,
HSV, HIV, influenza virus, and RSV are
susceptible to alcohols. Hepatitis B virus is an
enveloped virus that is somewhat less susceptible
but is killed by 6070 alcohol hepatitis C
virus also is likely killed by this percentage of
alcohol.
APIC guidelines Am J Infect Control 199624313-42
4
Cleaning

• Removing all foreign material from objects by
  using water and detergents or soaps and washing
  or scrubbing the object
• Must be done before any disinfection or
  sterilization process

5
Disinfection

• A process that eliminates many or all
  microorganisms except spores
• Done with liquid chemicals or by pasteurization
• Proper contact time and dilution of the
  disinfectant must be followed

6
Definitions

• High-level disinfection
• All microorganisms except high numbers of
  bacterial spores
• Intermediate disinfection
• M. tuberculosis, vegetative bacteria, most
  viruses, and most fungi
• Not necessarily kill bacterial spores

7
Sterilization

• A process that completely eliminates or kills all
  microorganisms

8
Classification of device, process, and products
Device Device Process Product
Classification Examples Process Product
Critical Implant, surgical instrument Sterilization Sterilant/disinfectant
Semicritical Flexible endoscope, laryngoscope, endotracheal tube High-level Sterilant/disinfectant
Thermometer, hydrotherapy tank Intermediate-level Hospital disinfectant with tuberculocidal activity
Noncritical Stethoscope, tabletops, bedpans Low-level Sterilant/disinfectant without tuberculocidal activity
9
Chemical disinfection

• Aldehydes glutaraldehyde ortho-phthaldehyde
  (OPA)
• Alcohol
• Biguanides chlorhexidine
• Halogen and halogen releasing agents chlorine,
  iodine
• Quaternary ammonium compound

10
Glutaraldehyde

• High-level disinfectant
• Working solution pH 7.5 to 8.5, 14 to 28 days
• Mode of action cross-linking with proteins,
  inhibit synthesis of DNA, RNA
• 2 vegetative bacteria lt 2 minutes, M.
  tuberculosis, fungi, viruses lt 10 minutes, spore
  of Bacillus Clostridium spp. 3 h
• Use medical equipment
• Toxic respiratory system

11
Glutaraldehyde

• Advantages
• Rapid low-temperature disinfection
• OPA has greater anti-mycobacterial activity, no
  activation required, less noxious, more stable
• Disadvantages
• Irritating
• Absorbed into plastics leads to toxicity (e.g.,
  colitis)

12
Alcohol

• Optimal conc. 60 to 80
• Not HIGH level (spores and hydrophilic virus are
  not destroyed)
• Use oral and rectal thermometers, small surfaces
  (multiple dose medication vials), external
  surface of equipment (stethoscope, ventilators,
  manual ventilation bags)

13
Biguanides

• Chlorhexidine (bisbiguanide)
• Insoluble in water
• Active against Gm ve gt Gm ve bacteria gt yeasts
  molds
• Not sporicidal
• Can be inactivated by nonionic surfactant
  presented in soaps, hand creams, and inorganic
  water contaminants (phosphate, chlorine)

14
Chlorine compound

• Concentration dependent
• 25 ppm mycoplasma and vegetative bacteria (lt1
  ppm) within seconds
• 100 ppm Bacillus subtilis spores within 5
  minutes, fungus lt 1 h
• 1000 ppm M. tuberculosis
• Household bleach 5.25 52,500 ppm

15
Iodophors

• Tincture of iodine
• 7.5 Povidone-iodine (PVP-I), 0.7 available
  iodine
• Bactericidal, fungicidal, tuberculocidal, and
  virucidal
• Short time residual effect

16
Quaternary ammonium compound benzalkonium
chloride

• Associated with many outbreaks including
  non-tuberculous Mycobacterium GNR
• Not recommended for use as skin and tissue
  disinfectant
• Use environmental sanitation of noncritical
  surfaces (floors, furniture, walls)

17
Problems associated with the use of disinfectants

• Ineffective cleaning
• Too low concentration
• Contaminants unlikely to survive in recommended
  use-dilution

18
(No Transcript)
19
The amount of use and costs of antiseptics/disinfe
ctants per bed per year
Danchaivijitr S et al. J Med Assoc Thai 2005 88
(Suppl 10) S133-9
20
Places where antiseptics/disinfectants were
prepared
Danchaivijitr S et al. J Med Assoc Thai 2005 88
(Suppl 10) S133-9
21
Persons who prepared antiseptics/disinfectants
used in wards
Danchaivijitr S et al. J Med Assoc Thai 2005 88
(Suppl 10) S133-9
22
Microbial contamination ()
Danchaivijitr S et al. J Med Assoc Thai 2005 88
(Suppl 10) S133-9
23
Danchaivijitr S et al. J Med Assoc Thai 2005 88
(Suppl 10) S133-9
24
Infection control in flexible endoscopy
Alvarado C et al. Am J Infect Control
200028138-55.
25
(No Transcript)
26
Agents recommended for high-level disinfection of
flexible endoscopes

• Glutaraldehyde preparations
• Peracetic acid
• Orthophalaldehyde

Alvarado C et al. Am J Infect Control
200028138-55.
27
Agents not recommended for disinfection of
flexible endoscopes

• Hypochlorites
• Quaternary ammonium compounds
• Not sporicidal, tuberculocidal, or viricidal
  against hydrophilic viruses
• Phenolics
• Intermediate-level disinfectants

Alvarado C et al. Am J Infect Control
200028138-55.
28
Disinfection of a Probe Used in Ultrasound-Guided
Prostate Biopsy
Rutala WA., et al. Infect Control Hosp Epidemiol
2007 28916-919
29
Main findings

• Disinfection (i.e., a reduction in bacterial load
  of greater than 7 log10 CFU) could be achieved if
  the needle guide was removed from the probe

Rutala WA., et al. Infect Control Hosp Epidemiol
2007 28916-919
30
Main findings

• If the needle guide was left in the probe channel
  during immersion in 2 glutaraldehyde,
  disinfection was not achieved (i.e., the
  reduction was approximately 1 log10 CFU)

Rutala WA., et al. Infect Control Hosp Epidemiol
2007 28916-919
31
Treatment of endoscope after disinfection or
sterilization

• Rinsing
• Sterile water
• Alcohol rinse followed by complete drying
• Only sterile water should be used for endoscopes
  that pass through sterile tissues.

Alvarado C et al. Am J Infect Control
200028138-55.
32
Treatment of endoscope after disinfection or
sterilization

• Drying
• Drying with alcohol and compressed air should be
  done between each patient use when tap water is
  used to rinse the endoscope channels and before
  storage whether tap water or sterile water is
  used.
• Storage

Alvarado C et al. Am J Infect Control
200028138-55.
33
Sterilization

• Heat sterilization
• Dry heat
• Moist heat pressure steam sterilizer (autoclave)
• Chemical
• Ethylene oxide
• Glutaraldehyde

34
Autoclave

• Steam must come into direct contact with the
  surface
• Air must be completely removed
• Downward displacement
• Pre-vaccuum

35
Flash sterilization

• Steam sterilization of patient care items for
  immediate use
• Not for convenience or an alternative to
  purchasing additional instrument sets or to save
  time
• Not recommended for implantable devices

36
Flash sterilization

• Lack of timely biologic indicators to monitor
  performance, absence of protective packaging
  following sterilization, possibility for
  contamination of processed items during
  transportation to operating rooms, and use of
  minimal sterilization cycle parameters (i.e.,
  time, temperature, pressure)

37
Parameters for flash sterilization
38
Ethylene oxide

• Extremely penetrative
• Non-corrosive
• Toxic, irritant, and explosive when mixed with
  air at conc. gt3
• Odorless

39
Quality assurance for sterilization

• Mechanical monitoring
• Exposure time, temperature, and pressure
• Ascertain that the sterilization system function
  within parameters
• Chemical monitoring
• Does not verify sterilization
• Indicate procedural errors and equipment
  malfunction

40
???????????????????
Mechanical monitoring ??????????????????
External chemical indicators ??????????????????????????????????????????????????????????
Internal chemical indicators ??????????????????? ?????????????????????????????????????????
Biological monitoring Daily or at least weekly
AAMI ,AORN ,CDC,CSA
41
Definition of a chemical indicators

• CI System that reveals a change in one or more
  predefined process variables based on a chemical
  or physical change resulting from exposure to a
  process.

42
CI classes

• Class 1 Process Indicators
• Used to show exposure to a process. No
  information about the success or failure of the
  process
• Class 2 Specific Test Indicators (e.g. BDT)
• Class 3 Single variable indicators
• Respond to a single variable in the process e.g.
  temperature

43
CI classes

• Class 4 Multivariable Indicators
• Respond to two or more variables in the process
• Class 5 Integrating Indicators (Chemical
  Biological Indicators)
• Respond in a way which mimics the response of a
  BI if used in the same process

44
CI classes

• Class 6 Emulating Indicators (Cycle
  Verification Indicators -Chemical Chart
  Recorders)
• Respond to all critical variables of the process
  at levels associated with acceptable sterilizing
  conditions e.g. 134 for 5 mins.

45
Quality assurance for sterilization

• Bowie-Dick test
• Performed daily, with pre-vacuum system, in an
  empty chamber
• Detect residual air in the sterilizer chamber

46
Biologic monitoring of steam sterilization

• Biologic indicators demonstrated bacterial growth
  from spore strips on 15 (12) out of 125 cycles
• Chemical indicators revealed a change of color to
  black after all 125 cycles

Kelkar U et al AJIC 2004, 512-513
47
BI changes

• Bacillus subtilis renamed to B. atrophaeus
• Bacillus stearothermophilus renamed to
  Geobacillus stearothermophilus

48
QA for sterilization

• Whenever sterilizers are used, they should be
  routinely tested with biological indicators to
  ensure they are working correctly
• Items that are sterilized should remain sterile
  until the package is torn, wet, or damaged.
  Sterility is a function of intact packaging, not
  time.

49
???????????????????????????????
??????????????????????????????????????????????????
??????????????????????????????????????????????????
?????? Steam 56 ? 1o C EtO 37 ? 1 o C
50
???????????????????

• ?????????????????????????????????????????? 8, 12,
  24 ??? 48??
• ??????????????????????????????????????????????????
  ??????????????????????????????????????
• ??????????????????????????????????????????????????
  ?????????????????????????

51
?????????
?????? ???????????????????????????????????????????
??????????????? 8, 12, 24, 48 ???????
??????????????????????????????????????????????????
?
52
??????????????

• ???????????
• ???????????????? ??????????
• ????????????????????????? Glutaraldehyde
  ????????????????????????????????????/?????????????
  
• ?????????
• ?????
• ???????