Sterilization & Decontamination in Research and Pharmaceutical

Transcription

1 Sterilization & Decontamination in Research and Pharmaceutical Presented by Daniel Caron Rencontres A3P Canada September 13 & 20, 2007

2 Principles of Steam Sterilization Steam is the ideal sterilant for items that can withstand moisture and high temperatures because it is: nontoxic readily available fairly easy to control

3 Principles of Steam Sterilization Steam is Water in the Vapor State Steam Heats by Condensing and Giving Up Energy 6.8X More Energy Required Boiling from liquid to Vapor at 212F than heating from 70F- 212F By-product is Condensation Remains on product Rolls off

4 Principles of Steam Sterilization Three factors are critical to assure successful steam sterilization: time temperature moisture

5 Principles of Steam Sterilization TIME All organisms do not die at the same time. The number of survivors is usually plotted on a semi-logarithmic scale. A straight line survivor curve usually results.

6 Microbial Death Rate Curve that Illustrates Concept of D-ValueD Number of Survivors 10,000 Log Number of Survivors 4 1, D-Value D-Value is the time to reduce the microbial population by 90% or 1 log Exposure Time (Minutes) -2

7 Principles of Steam Sterilization Temperature The second critical factor in steam sterilization is the temperature of the saturated steam. Increasing temperature dramatically reduces the time needed to achieve sterilization.

8 Time to Achieve Equivalent Microbial Lethality at Different Exposure Temperatures Population 10E6, D value 2 minutes 285 F (140 C) (.13 Minutes ) 270 F (132 C) ( 0.9 Minutes ) 250 F (121 C) 12 Minutes 212 F (100 C) 80 Hours 200 F (93 C) 321 Hours 176 F (80 C) 643 Hours MINUTES HOURS

9 Principles of Steam Sterilization Moisture Steam denatures or coagulates proteins. Dry heat is an oxidation process with different kinetics - it requires much higher temperatures and longer exposure times. B. stearothermophilus spores - killed in minutes at 121 C (250 F) when saturated steam is used more than 6 hours are required to dry heat at 121 C.

10 The following illustration shows the basic components of a typical prevacuum steam sterilizer: Chamber Safety Valve Air Filter Jacket Safety Valve Jacket / Chamber Steam Supply Pressure Regulator PC Jacket Steam Supply Chamber Temperature Sensor Steam Supply Jacket Bleed Valve Jacket Trap Chamber Trap Vacuum System To Waste

11 Principles of Steam Sterilization The Steam Sterilization Cycle A steam sterilization cycle consists of three phases: Heating (pre-conditioning) phase Sterilization (exposure) phase Cool-down (post conditioning) phase

12 The Steam Sterilization Cycle Heating (pre-conditioning) phase - Steam enters the sterilizer chamber and air is removed by either: gravity displacement mechanically (prevacuum)

13 The Steam Sterilization Cycle Sterilization (exposure) phase - Load is exposed to steam at a set temperature (measured and controlled by a temperature sensor in the drain line or product) for a set time.

14 The Steam Sterilization Cycle Cool-down (post-conditioning) phase - Sterilizer chamber is exhausted to atmospheric pressure followed by circulating air through the chamber or by drawing vacuum. Jacket heat may or may not be maintained during the drying phase.

15 Basic Gravity and Prevac Cycles Pre-Vac Gravity

16 Basic Gravity Cycle Applications: Empty glassware Instruments Basic Gravity Cycle Open, empty pans, vats, carboys

17 Basic Liquid Cycle (Modified gravity cycle) Generally used to process Media/Liquids in open containers Water TSB TSA Filled bottles / tubes with loose caps Generally at 121 o C

18 Basic Gravity Cycle Pre-conditioning and Exposure Two Methods of Controlling the Cycle Control by Temperature Probe in Drain Timed Control using Probe in Product F o

19 Basic Gravity Cycle Pre-conditioning and Exposure May use F o load probe in liquid loads if it is available in the sterilizer Advantages produces desired lethality minimal effect on product optimizes the exposure period Can use time at temperature if probes are not available (overkill method)

20 What is F 0 F0 as a Function of Temperature Lethality Curve C C C F 0 Value C C C Fo Calculation *Reference Temperature C Z - Value = 10 C

21 Gravity Cycle Post- conditioning Liquid Cycles are returned to atmospheric pressure slowly to Prevent boil-over Prevent liquid loss Rate of slow exhaust depends on Volume of liquid per flask / tube Total load capacity If there is a jacket cooling process built into the sterilizer

22 Prevac or Pulsing Vac Cycles Generally used to process dry goods articles in open trays porous goods such as textiles open, unfilled glassware/plastic bottles rubber stoppers filter cartridges Disc filters

23 Prevac Cycle Loads Metal articles Porous goods (textiles) Glassware (open) Glassware in pouches Plastics (open) Plastics in pouches Rubber stoppers Filter cartridges Disk filters 2.1.3

24 Prevac Cycle Pre-conditioning Number and depth of vacuums during pre-conditioning can be user selectable based on degree of difficulty to penetrate product with steam Tygon tubing may take several pulses/vacs to penetrate to center of tube Long lengths may require deeper vacuum Large metal items may require several pulses to heat

25 Prevac Cycles Product Constraints Ability of the product to withstand ; vacuums pressure / vacuum rates Peel pouches may burst Covers may be blown off of covered pipe ends May need to control rates if available on sterilizer

26 Prevac Cycle Exposure Phase Timed Based on drain line temperatures Generally at 121 o C but could be at 132 o C Overkill method employed

27 Post-conditioning phase Single deep vacuum, hold Used to dry the load Basic cycle draws a single deep vacuum and holds Hold time varies may be minutes or longer Time depends on material that comprises load packaging level of dryness required

28 Post-conditioning Pulsing Vac Cycle Pulls vacuum with alternating pressurization with air Used for peel pouched items, items with low specific heat (rubber goods) May be unheated or optional heated

29 Gravity Cycles GRAVITY DISPLACEMENT >Provided on both gravity and prevacuum sterilizers >Operates on the downward air displacement air-removal principle. >Used for sterilizing nonporous heat and moisture stable goods at 250 or 270 F (121 or 132 C). Gravity

30 Isothermal Cycles Isothermal ISOTHERMAL CYCLE- Optional cycle >Designed for low temperature sterilization of heat sensitive and heat coagulable materials. >Used for pasteurization, melting agar, inspissation (increase in viscosity by dehydration of highprotein containing media), or fractional sterilization (Tyndallization) >Temperatures are controlled at 78C(172F), 88C (190F), and 104C(219F)

31 Liquid Cycles Liquids LIQUID CYCLE- Modified Gravity Cycle >Provided on both gravity and prevacuum sterilizers >Used for sterilizing liquids, in flasks or test tubes with vented closures, at 250 F (121 C). >Optimal Solution Cooling is on Century Units

32 Prevac Cycles Pre-Vac PREVACUUM >Available only on prevacuum sterilizers >Employs a mechanical air-removal system >For efficient, high-volume processing of porous heat and moisture stable materials, such as fabrics, wrapped hard goods, and container systems at 250 or 270 F (121 C or 132 C).

33 Decontamination Cycles Optional cycle designed to decontaminate all effluents from the sterilizer chamber prior to discharge to drain During purge, pre-steam pulses, and heat-up phases, steam is admitted through the drain port (located on the sterilizer chamber floor). Helps to heat any condensate on the chamber floor to sterilizing temperatures. Potentially contaminated air is pushed upward and discharged through the vent in the top of the chamber. Gaseous exhaust filtered through a 0.2 micron (0.2 micrometer) bacterial retentive filter before exiting to the sterilizer vacuum system, building drain system, and surrounding environment.

34 Decontamination Cycle The temperature is monitored and controlled using a temperature probe located after the bacterial retentive filter housing. The bacterial retentive filter is also sterilized during the exposure phase. After the exposure phase the decontaminated condensate that has accumulated in the drain line and chamber floor is discharged via the drain port located on the chamber floor. All liquid effluents are decontaminated prior to discharge to drain.

35 Standard Steam Flow

36 Decontamination Cycles DECONTAMINATION (EFFLUENT DECONTAMINATION) CYCLE

37 Decontamination Cycles

38 LABORATORY CYCLES Preconditioning Exposure Postconditioning Gravity Purge, Heat up Timed Vacuum Dry Prevac Purge, Prevac Pulses, Heat-up Timed Vacuum Dry Liquids Purge, Heat-up Timed F0 Optional Slow Exhaust Isothermal Purge, Heat-up Timed Slow Exhaust Decontamination Purge, Prevac Pulses, Heat-up Timed Vacuum Dry

39 B Process Cycles >General purpose steam sterilization cycle applicable for all dry goods and porous loads. >Suitable products include filters, equipment parts, instruments, textiles, and rubber goods. >Primarily used for production, clean room supplies and utensils, and production support. >Features a preconditioning air removal phase using vacuum and steam pulses. >Drying can be accomplished by deep vacuum, vacuum pulsing, or fast exhaust.

40 B Process Cycles Continued >General purpose steam sterilization cycle applicable for liquids in open / vented containers e.g., culture media with vented closures. >May be used for microbial decontamination of liquids in vented/open containers or vented red/orange bags. >Utilizes a forced air preconditioning and a user programmable rated slow exhaust. >Steam-to-jacket is turned off during slow exhaust.

41 CA Process Cycles >Designed for liquid products in vented or sealed containers. >Primarily used for production, media preparation, and R&D purposes when liquids are in open containers or cooling time is less critical. >Employs forced air removal during preconditioning. >No circulating water in the sterilizer jacket is used. >Maintains sterile air overpressure during the cooling phase to cool the load and prevent the product from boiling.

42 C Process Cycles >Designed for liquid products in vented or sealed containers. >Primarily used for production, media preparation, and R&D purposes when liquids are in open containers or cooling time is less critical. >Employs forced air removal during preconditioning and indirect cooling by circulating water in the sterilizer jacket. >Maintains sterile air overpressure during the cooling phase to cool the load and prevent the product from boiling.

43 CF Process Cycles >Designed for liquid products (LVPs or SVPs) in vented or sealed containers. >Primarily used for production, media preparation, and R&D purposes when liquids are in open containers or cooling time is less critical. >Employs forced air removal during preconditioning and indirect cooling by circulating water in the sterilizer jacket. >Maintains sterile air overpressure during the cooling phase to cool the load and prevent the product from boiling. >A fan is present in the sterilizer chamber to assist in cooling the product during post conditioning. >The circulated air with fan and jacket cooling process significantly reduces the cycle time by approximately 50% over a jacket cooling process, depending on the application.

44 Steam-Air-Mixture (A/C) >Cycle designed for terminal sterilization of liquids in plastic or glass containers (e.g. pouches, bottles, LVPs, SVPs and blister packs) that must be dry at the end of the cycle. >The cycle employs an over pressurized air/steam mixture to sterilize. >Counter pressure is maintained based on the product temperature through the entire cycle. >Cooling is performed by fan-circulated air, cooled by indirect jacket cooling. >Allows immediate post-cycle product processing (e.g. labeling and packaging).

45 Steam-Air-Mixture (A/C)

46 Superheated Water (RP) >Designed for terminal sterilization of liquids in plastic or glass containers (e.g. pouches, bottles, and blister packs). >Employs an over pressurized water spray to sterilize; No pure steam is required. >Air counter pressure is employed throughout the entire cycle based on the product temperature. >Extremely efficient cooling time.

47 RP Process Cycles

48 G Process Cycles >Designed for terminal sterilization of liquids in glass containers (vials, bottles). >For non-vented containers only. >Employs a purified water spray during cooling only. >Air counter pressure is also employed during the cooling based on the product temperature.

49 GΔT Process Cycles >Designed for terminal sterilization of liquids in glass containers (vials, bottles). >For non-vented containers only. >Employs a temperature controlled purified water spray during cooling only. >Air counter pressure is also employed during the cooling based on the product temperature. >The cooling time, delta and final load temperature are configurable to protect the load from thermal shock.

50 Process Cycles Products to Sterilize Cycle End Support Air Media Precond. Exposure Postcond Cooling Media Open containers, vented flasks, textiles, components, utensils Open / vented containers, sealed bottles Open / vented containers, sealed bottles Open / vented containers, sealed bottles B DRY Steam Steam-to-jacket off; Heat loss by conduction CA DRY Steam X Steam-to-jacket off; Air overpressure C DRY Steam X Air overpressure/ Jacket water CF DRY Steam X Air circ./ Jacket water/ Fan on, during cooling only Sealed glass bottles G WET Steam X Water/jacket water/ Air overpressure Sealed glass fragile bottles GΔT WET Steam X Water temp, controlled / jacket water/ Air circ Sealed glass or Flexible containers E.g. plastic bags, blisters, syringes, containing liquids Sealed glass or Flexible containers; E.g. plastic bags, blisters, etc. A/C DRY Steam X X X Air / Jacket water/ Fan on during entire cycle RP WET Water X X X Water/ Air circ./ Jacket water

51 Cycles for Solutions CYCLE TYPE STERILIZING MEDIA PRE- CONDITIONING LOAD STATUS AT END OF CYCLE SPEED OF COOLING B PROCESS WITH SLOW EXHAUST WITH RATES STEAM FORCED AIR; WITH OR WITHOUT RATES DRY EXTERNALLY AND APPROXIMATELY AT BOILING TEMPERATURE SLOW CA Process STEAM FORCED AIR; WITH OR WITHOUT RATES RELATIVELY DRY EXTERNALLY AND AT COOLING TEMPERATURE SET POINT (VACUUM DRYING MAY BE ADDED AFTER COOLING) SLOWER THAN C PROCESS, BUT FASTER THAN B PROCESS C Process STEAM FORCED AIR; WITH OR WITHOUT RATES RELATIVELY DRY EXTERNALLY AND AT COOLING TEMPERATURE SET POINT (VACUUM DRYING MAY BE ADDED AFTER COOLING) MODERATE CF Process STEAM FORCED AIR; WITH OR WITHOUT RATES DRY EXTERNALLY AND AT COOLING TEMPERATURE SET POINT (VACUUM DRYING MAY BE ADDED AFTER COOLING) MODERATELY FAST (FASTER THAN C PROCESS, BECAUSE OF FAN)

52 Cycles for Solutions Continued CYCLE TYPE STERILIZING MEDIA PRE-CONDITIONING LOAD STATUS AT END OF CYCLE SPEED OF COOLING G STEAM FORCED AIR; WITH OR WITHOUT RATES WET, AND AT COOLING TEMPERATURE SET POINT (VACUUM DRYING MAY BE ADDED AFTER COOLING) MODERATE GΔT STEAM FORCED AIR; WITH OR WITHOUT RATES WET, AND AT COOLING TEMPERATURE SET POINT (VACUUM DRYING MAY BE ADDED AFTER COOLING) MODERATE; MORE CONTROLABLE THAN G PROCESS A/C STEAM (MIXED BY FAN WITH STERILE AIR COUNTER- PRESSURE) AC HEATING (STEAM AND STERILE AIR COUNTER- PRESSURE IN CHAMBER w/ FAN) DRY EXTERNALLY AND AT COOLING TEMPERATURE SET POINT; READY FOR LABELING OR PACKAGING MODERATELY FAST RP STERILE SUPERHEATED WATER (with STERILE AIR COUNTER- PRESSURE) STERILE SUPERHEATED WATER w/ STERILE AIR COUNTER- PRESSURE WET EXTERNALLY AND AT COOLING TEMPERATURE SET POINT MODERATELY FAST

53 Common Problems and Misconceptions About Steam Sterilization

54 Common Problems Possible sources of air in chamber: Air is generally a deterrent to sterilization PACK STERILIZER CHAMBER AIR POCKET AIR Leak (during vacuum) in piping or door gasket Insufficient prevacuum Air entrained in steam STEAM + AIR STEAM + AIR SPORES STERILIZER DRAIN

55 Common Problems Steam Quality Issues Wet Steam Wet steam is undesirable - it has less energy than dry steam and it can cause wet loads STERILIZER CHAMBER PACK Water Droplets The packaging used for sterile products prevents recontamination when dry, but its bacterial retentive properties will be adversely affected by moisture. Wet loads can be considered to be nonsterile. Causes - Wet steam may be caused by excessive pressure drops on the boiler due to high demands. STEAM + Water STERILIZER DRAIN STEAM + Water

56 Misconception Assumption: Everything Can Be Sterilized Facts Closed valves on containers do not permit steam penetration. Open all valves O-rings and seals retard steam penetration. May need to remove o-rings or extend processing times Upright, empty containers are difficult to remove air from with a gravity cycle

57 Test Tubes in Rigid Container Fact: Solid bottom containers retard steam penetration Bottom set of tubes in container Top set of tubes above container

58 Effects of Rigid Bottom Container Temperature F Top Test Tube Rack Bottom Test Tube Rack Time (Minutes)

59 Misconception Assumption: Exposure Time for a Liquid Cycle Means That the Product is at Temperature for that Period Fact: Exposure time must account for product comeup and desired time at temperature

60 Come-up Rates for Two Different Flask Sizes Chamber Drain Media Load 1 Media Load

61 Misconception Assumption: The attainment of C is a significant requirement to sterilize. Fact: The objective of steam sterilization is to deliver lethality. F 0 accumulates at all spore killing temperatures although it is slower at lower temperatures.

62 Misconception Assumption: A steady state temperature distribution range of +/-.5 0 C is necessary for all loads. Fact: Desirable for terminal sterilization in final containers. Not required for sterilization of production equipment. Distributions of 1 0 C to 2 0 C are acceptable

63 Misconception Assumption: Fixed load patterns are required for proper sterilization Fact: It is not as much the location of the items, but the material makeup, wrapping, mass, loading procedures and orientation of the load that define difficult-to-sterilize locations

64 QUESTIONS?

65 MERCI!