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 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

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

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 < 2 minutes, M. tuberculosis, fungi, viruses < 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 > Gm –ve bacteria > 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 (<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

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

19. 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

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 2000;28:138-55.

26. 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.

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 2000;28:138-55.

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

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; 28:916-919

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; 28:916-919

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 2000;28:138-55.

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 2000;28:138-55.

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. >3% • 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. ความถี่ในการตรวจสอบ 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. ขั้นตอนการตรวจสอบด้วยสปอร์เทสต์ขั้นตอนการตรวจสอบด้วยสปอร์เทสต์ นำสปอร์เทสต์มาทำการอุ่นเชื้อในเครื่องอุ่นเชื้อที่สามารถควบคุมอุณหภูมิให้มีความเหมาะสมในการเจริญเติบโตได้ดี Steam 56  1oC EtO 37  1 oC

50. การอ่านผลการตรวจสอบ • ตรวจดูการเปลี่ยนแปลงสีของน้ำเลี้ยงเชื้อทุก 8, 12, 24 และ 48ชม • การเปลี่ยนแปลงสีเป็นสีเหลืองแสดงว่าการทำให้ปราศจากเชื้อไม่สมบูรณ์เชื้อโรคถูกฆ่าตายไม่หมด • ไม่มีการเปลี่ยนแปลงสีแสดงว่าการทำให้ปราศจากเชื้อสมบูรณ์เชื้อโรคถูกฆ่าตายหมด