Cleaning/decontamination, disinfection, and sterilization Kumthorn Malathum, MD Chair, ICC, Ramathibodi Hospital

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

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 60%–70% alcohol; hepatitis C virus also is likely killed by this percentage of alcohol. APIC guidelines Am J Infect Control 1996:24;313-42

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

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

Definitions High-level disinfection Intermediate 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

Sterilization A process that completely eliminates or kills all microorganisms

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

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

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 < 2 minutes, M. tuberculosis, fungi, viruses < 10 minutes, spore of Bacillus & Clostridium spp. 3 h Use: medical equipment Toxic: respiratory system

Glutaraldehyde Advantages Disadvantages 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)

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)

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

Chlorine compound Concentration dependent: 25 ppm: mycoplasma and vegetative bacteria (<1 ppm) within seconds 100 ppm: Bacillus subtilis spores within 5 minutes, fungus < 1 h 1000 ppm: M. tuberculosis Household bleach 5.25% = 52,500 ppm

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

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)

Problems associated with the use of disinfectants Ineffective cleaning Too low concentration Contaminants unlikely to survive in recommended use-dilution

The amount of use and costs of antiseptics/disinfectants per bed per year Danchaivijitr S et al. J Med Assoc Thai 2005; 88 (Suppl 10): S133-9

Places where antiseptics/disinfectants were prepared Danchaivijitr S et al. J Med Assoc Thai 2005; 88 (Suppl 10): S133-9

Persons who prepared antiseptics/disinfectants used in wards Danchaivijitr S et al. J Med Assoc Thai 2005; 88 (Suppl 10): S133-9

Microbial contamination (%) Danchaivijitr S et al. J Med Assoc Thai 2005; 88 (Suppl 10): S133-9

Danchaivijitr S et al. J Med Assoc Thai 2005; 88 (Suppl 10): S133-9

Infection control in flexible endoscopy Alvarado C et al. Am J Infect Control 2000;28:138-55.

Agents recommended for high-level disinfection of flexible endoscopes Glutaraldehyde preparations Peracetic acid Orthophalaldehyde Alvarado C et al. Am J Infect Control 2000;28:138-55.

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 2000;28:138-55.

Disinfection of a Probe Used in Ultrasound-Guided Prostate Biopsy Rutala WA., et al. Infect Control Hosp Epidemiol 2007; 28:916-919

Rutala WA., et al. Infect Control Hosp Epidemiol 2007; 28:916-919 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; 28:916-919

Rutala WA., et al. Infect Control Hosp Epidemiol 2007; 28:916-919 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; 28:916-919

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 2000;28:138-55.

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 2000;28:138-55.

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

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

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

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)

Parameters for flash sterilization

Ethylene oxide Extremely penetrative Non-corrosive Toxic, irritant, and explosive when mixed with air at conc. >3% Odorless

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

ความถี่ในการตรวจสอบ Mechanical monitoring ทุกครั้งที่ทำการอบ External chemical indicators ทุกห่อยกเว้นถ้าสามารถมองเห็นตัวบ่งชี้ทางเคมีภายในได้ชัดเจน Internal chemical indicators ทุกห่อถ้าปฏิบัติได้ ควรใส่ในห่อขนาดใหญ่และห่อเครื่องมือผ่าตัด Biological monitoring Daily or at least weekly AAMI ,AORN ,CDC,CSA

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.

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

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

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.

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

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

BI – changes Bacillus subtilis renamed to B. atrophaeus Bacillus stearothermophilus renamed to Geobacillus stearothermophilus

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.

ขั้นตอนการตรวจสอบด้วยสปอร์เทสต์ นำสปอร์เทสต์มาทำการอุ่นเชื้อในเครื่องอุ่นเชื้อที่สามารถควบคุมอุณหภูมิให้มีความเหมาะสมในการเจริญเติบโตได้ดี Steam 56  1o C EtO 37  1 o C

การอ่านผลการตรวจสอบ ตรวจดูการเปลี่ยนแปลงสีของน้ำเลี้ยงเชื้อทุก 8, 12, 24 และ 48ชม การเปลี่ยนแปลงสีเป็นสีเหลืองแสดงว่าการทำให้ปราศจากเชื้อไม่สมบูรณ์เชื้อโรคถูกฆ่าตายไม่หมด ไม่มีการเปลี่ยนแปลงสีแสดงว่าการทำให้ปราศจากเชื้อสมบูรณ์เชื้อโรคถูกฆ่าตายหมด

การอ่านผล Successful Sterilization Process Failed Sterilization Process อ่านผล จากการเปลี่ยนแปลงสีของน้ำเลี้ยงเชื้อภายหลังการอุ่นเชื้อที่ 8, 12, 24, 48 ชั่วโมง ถ้ามีการเปลี่ยนแปลงสีเป็นเหลืองให้ทำการอ่านผลได้เลย

ปัญหาที่พบบ่อย แช่ก่อนล้าง แช่ของที่ควรนึ่ง หรืออบแก๊ส การระบายอากาศในห้องที่ใช้ Glutaraldehyde ระบบการตรวจสอบการทำงานของเครื่องนึ่ง/เครื่องอบแก๊ส โครงสร้าง บุคคล สถานที่