Microbiology lab QC

this lecture describes the various procedures and maintenance steps that should be taken to insure that all lab equipment are working well in a controlled manner for the guarantee of accuracy of microbiological test results.

1. Quality Assurance & Quality Control in Microlabs Dr Mostafa Mahmoud Ahmed, Ph D Consultant Microbiologist, GDHA , Riyadh, KSA . Associate Prof. of Microbiology & Immunology. Faculty of Medicine – Ain Shams University

2. The standardized definition of quality refers to all those features of a product (or service) which are required by the customer. “Quality management“ means what the organization does to ensure that its products or services satisfy the customer's quality requirements and comply with any regulations applicable to those products or services. Definition of Quality & Quality Management

3. How do you ensure quality in laboratory? •By controlling all the factors that influence generation of reliable results

4. Quality Assurance (QA) The sum total of all activities that are performed to ensure quality of the product Regarding the clinical lab: QA is the sum total of all activities that are undertaken to ensure generation, and utilization, of reliable and accurate results/data

5. Objectives of quality in lab Support provision of high quality health-care – Reduce morbidity – Reduce mortality – Reduce economic loss Ensure credibility of lab Generate confidence in lab results

6. Consequences of poor quality Inappropriate action – Over-investigation – Over-treatment – Mistreatment Inappropriate inaction – Lack of investigation – No treatment Delayed action Loss of credibility of laboratory Legal actions.

7. Factors influencing quality Within Laboratory Outside Laboratory

8. Factors affecting quality (Analytical) Proficiency of personnel Reagents stability, integrity and efficiency Equipment reliability Specificity & sensitivity of selected test Procedural reliability using standard operating procedures Use of appropriate controls Documentation Assessment

9. Maintenance and Quality Control of Laboratory Equipment

10. Factors affecting the optimal utilization/ performance of equipment: Proper installation Calibration Validation Regular maintenance (including the preventive ones) Training of operators

11. Pre-purchase QC considerations for instruments/equipment Purchase instruments/equipment from reputed manufacturers, with long standing, and who in turn practice Quality Standards and GMP . Specifications should fit the intended purpose, with comparative cost-effectiveness-compatible with availability of reagents on long term basis. Specifications should conform to local conditions (power supply, humidity and other climatic factors). Maintenance service ( through AMC or other channels ) should be preferably local, prompt, and cost-effective Should not be a very complex instrument -technical safety and moderate running cost. Operating Manual -containing also the instructions for maintenance and “trouble shooting” list-should be provided.

12. The Equipment File Form 1. Unit identification: Name of the Unit ___________________________________ Manufacturer ____________________________________ Serial No.____________________________________ Model No.____________________________________ Hosp./Lab No.____________________________________ Location____________________________________ 2. Warranty information: Date of Purchase____________________________________ Date Received____________________________________ Manufacturer’s Warranty # Covers a) ______________ From _______ To ________ b) _________________ From _______ To________ c) _________________ From _______ To ________ For Service, call _____________________________________ Address_____________________________________ Telephone #_____________________________________ Other Warranties Name _____________________________________ Address_____________________________________ Telephone #_____________________________________ Covers a) ________________ From ________ To ________ b) ________________ From ________ To ________

13. The Equipment File Form (Contd.) 3. Service Contracts: Name --------------------------------------------------------------------------Address_____________________________________ Telephone #__________________________________ Covers a) ________________ From ________ To ________ b) ________________ From ________ To ________ c) ________________ From ________ To ________ 4. Performance Monitoring: Frequency Nature of Maintenance _____________ ___________________________________ ----------------------- ----------------------------------------------------------- ----------------------- ----------------------------------------------------------- 5- other files to be included: User’s manual Incident reports Training and privileged persons for this equipment

14. Microscopes (bright field) Action required After use Daily Weekly Annually Clean oil immersion & objective lens paper * Remove slides * Cover microscope with dust cover * Adjust optic system * Clean optic system & microscope *- Overhaul microscope *

15. Centrifuges Before using, ensure that -the heads are symmetrically loaded ; the tube caps are sealed tubes are in safety centrifuge cups ; swinging buckets are symmetrically arranged. Check the centrifuge, after each run, for cleanliness and accidents. Centrifuge is calibrated with a tachometer or strobe light annually/ semiannually, depending upon frequency of its usage.

16. Centrifuges checklist Action required Quarterly Semiannually Annually Check with tachometer/strobe * Or * Check timer * Check brushes & internal parts * Check balance of rotors & trunnions * Recertify *

17. Freezers, Incubators & Refrigerators A Temperature log sheet should be placed on each piece of equipment, and the temp. be recorded first thing in the morning. A temperature variation of ± 1 C is acceptable for most pieces of equipment If 37 C is desired, then set the instrument at 36 C .

18. Freezers, Incubators & Refrigerators checklist Function Daily Monthly Quarterly Semi-annually Check temperature * Check pilot lights * Check doo-seal * Defrost, clean or both * Recalibrate thermometer * Check level *

19. Incubators Calibration-corrected temperature recorded twice daily for days in use, readings separated by at least 4 hours . Refrigerator Temperature recorded for days in use, at least once per day.

20. Water Baths - Should be filled with only distilled water (to prevent accumulation of salts on the walls) - Temperature variation of ±1 C is acceptable Function Daily Monthly Semi-annually Record temperature * Check water level * Replace water * Clean bath * Recalibrate thermometer *

21. Autoclaves Should be checked each Friday with commercially available spore strips. This will enable incubation of the strips over the week end, with final report by Monday. Whenever materials are being autoclaved in autoclave bags, do not tie the bags tightly, to permit the steam to permeate into all parts within the bag.

22. Autoclave Function Each load Weekly Monthly Semi-annually Record temperature & pressure * Sensitive indicator tape * Spore strip * Clean autoclave * Check doo gasket * Recalibrate and check temp and pressure & timer *

23. ELISA READER Special precaution: Keep the top of the Reader clear; to avoid over heating, the cooling fan inlet must not be blocked or covered Place the Reader on a flat surface, free of dust, solvents, acidic vapours , vibration and direct sunlight Reader should be away from freezers, so that cold wet objects will not be placed on it inadvertently

24. QC procedure and routine maintenance Frequency Activity Daily Clean plate carrier, top of instrument and display window Every 3 months Clean air filters (if applicable) Clean and lubricate plate support guide bar Every 6 months Check-Linearity; Repeatability; Diode; Accuracy; and Mechanical alignment

25. Hot Air Oven Used for drying glass ware To sterilize metal and some high temperature-stable glass objects General precautions: – Place on a level bench top – Not near autoclaves, direct sun light or areas exposed to heat – At least 5 cm (2”) space all-round the oven, to facilitate air-circulation. – No explosives, combustibles or flammables in oven – Do not heat food, oily reagents in oven – Do not sterilize liquids in hot-air-oven – Do not stack glass ware; may lead to breakage – Do not sterilize powders, oily substances and standard glass ware by dry heat Routine QC: 1. Record oven temperature each time it is used 2. Semi-annually, clean up the interior parts 3. Calibrate the gauge or Hg-bulb thermometer once every 6 months, using a standard thermometer.

26. Biological Safety Cabinets Whenever the cabinet is in use, nothing should be placed on the grid panels , as this could disrupt the air-flow pattern Air velocity across the opening of the cabinet should be at least 75 linear ft./min. (The National Sanitation Foundation ( NSF ) Standards. For Class-II, cabinets) ; cabinet should be set at 90 –100 lft ./min., across the opening of the cabinet UV lamp to be replaced when the output is 70% or less of its initial rated output (= 253.7 nm)

27. Biological Safety Cabinets checks Action Required Daily Bi-monthly Monthly Semi-annually Check air pressure gauge * Check air-flow pattern (with a smoke stick) * Disinfect the cabinet * Check air velocity (across front) * Clean UV Lamp (with alcohol gauze) * Check UV lamp output * Recertify cabinet *

28. pH Meter Action Required Each use Daily Set temperature compensation (if not automatic) * Standardize against certified buffer * Check electrode * Ensure that electrode is immersed in neutral buffer * Meter standardized each use period with pH 7.0 and either 4.0 or 10.0 buffers, with date and buffers recorded in log book. Commercial buffer solutions dated when received and opened and discarded by expiration date.

29. Pipettes Of various kind –to deliver milliliter to micro liter volumes, manual or automated, repeater, adjustable volume, single or multichannel models. Basically, it is either air-displacement mechanism or those which use a plunger mechanism; in general, the positive displacement pipettes (plunger type) are considered more accurate for small volumes. Volumetric measurement using pipettes is potential source of error in a microbiology laboratory. A small error in pipetting can cause a large error in the final result. Pipettes are used for a number of important purposes –to dilute sera, set up quantitative cultures, to prepare inocula for antimicrobial susceptibility tests, to add ingredients to media/reagents or specimen during test procedures etc. It is therefore very important that the accuracy and precision of the pipettes is maintained at all times .

30. Pipettes maintenance Calibration methods for pipettes: Gravimetric, spectrophotometric , and colorimetric methods are the most convenient and commonly used. Method Basis Limitation Gravimetric 1 ml of water = 1 g Volume. Dispensed must (adjusted for temperature & pressure) Volume dispensed must be > 0.002 ml Spectrophotometric Absorbance of K2Cr2O7 used to create calibration curve Volume dispensed must be > 0.01 ml Colorimetric (for quantitative loops) Absorbance of Evans blue dye used to create calibration curve Loop volume between 0.01-0.001 ml

31. Calibration of pipettes: special precautions Use the same tip for all deliveries during the calibration procedure, whether the pipette is used for repetitive dispensing of several aliquots of same liquid OR for transferring single aliquots of different liquids. ‘ Prerinsing ’ is precoating of the inside of the tip with the liquid being dispensed. Aspirate an aliquot of the liquid into the tip, and then dispense it back into the original container or discard it. Prerinsing improves the uniformity and precision by providing identical contact surface for all aliquots. Temp. of pipettes to be calibrated, room air, test liquid (water) and other equipment should be identical (±0.5 C ) Use water with no visible air bubbles; air bubbles alter measured volumes. Complete weighing step quickly. Use a lid on the weighing vessel to decrease evaporation. This will obviate the need for an evaporation factor in the calculations.

32. Analytical Balances Action needed Each use Daily Quarterly Annually Use weighing papers/boats * Clean pan & base of balance * * Ensure balance level * Adjust zero point * Lubricate when necessary * Calibrate with standard weights * Recertify balance *

33. Balance Calibrated monthly using American Society for Testing and Materials (ASTM) type 1,2 or 3 weights (minimum of 3 traceable weights which bracket laboratory weighing needs.) Non-reference weights calibrated every six months with reference weights. Annual service contract established, records available of most recent calibration and correction values on file and used. Reference weights recertified if damaged or corroded.

34. Methods of Validating Sterilization Processes Process Physical Methods Chemical Methods Biological Methods Dry Heat Temperature Recording Charts Colour Change Indicators* Bacillus subtilis ** ( ATCC # 9372) Moist Heat Temperature Recording Charts Colour Change Indicators* Bacillus stearothermophilus ** ( ATCC #7953) * “OK Indicator Strips” = what is the manufacturer? “Self Adhesive Autoclave Tape” = Manufacturer ?? “Self Adhesive Dry heat Label” = manufacturer ?? “Temperature” Indicators- for steam and dry sterilization **As spore strips and Prospore ampoules (10 5 -10 6 spores /strip or ampoule)

35. Biological Sterilization Indicators Sterilization Method Biological Indicator Steam Bacillus stearothermophilus Dry Heat Bacillus subtilis var. niger Ethylene Oxide Bacillus subtilis var. globigii Ionizing Radiation Bacillus pumilus Filtration Pseudomonas diminuta Heat resistant spores of B. stearothermophilus are dried on paper treated with nutrient medium and chemicals. After sterilization, the strips are incubated for germination and growth. A colour change indicates whether they have or have not been activated.

36. Quality Control of glassware All chipped, damaged or etched glassware should be discarded to prevent accidents. Sterilized glassware must be checked for sterility on a regular basis, and then stored for not >3 weeks prior to use. Sterilized glassware as well as clean glassware should be covered with aluminum foil. All glassware should be free of detergent.

37. Glassware/ Plasticware Graduated cylinders and precalibrated containers used to measure sample volumes accurate with a tolerance of 2.5% or less. Glassware inhibitory residue test performed on initial use of washing compound and whenever different detergent used. Batches of dry glassware spot-checked for pH reaction. Sterility of each lot of sample containers confirmed by adding sterile non-selective broth to at least one container, incubating at 35 o C for 24 hours and checking for growth. Sample bottles hold at least 120 ml and have dechlorinating agent.

38. Thermometers Glass and electronic thermometers calibrated annually, dial thermometers quarterly, at the temperature used, against reference National Institute of Standards and Technology ( NIST ) thermometer. Calibration factor marked on thermometer and calibration date and factor recorded. Thermometers discarded if off more than 1 o C from reference thermometer. N.B. NIST stops supporting mercury thermometers starting from 1-3-2011

39. UV Lamp If used to sanitize, tested quarterly with meter or by agar spread plate method. •UV lamp for fluorogenicmethods should be 6 watt.

40. Reagent-Grade Water Quality of reagent water should be tested for: Conductivity Heavy metals Chlorine residual Heterotrophic plate count bacteria Bacteriological quality of reagent water

41. Dilution/ Rinse Water Each batch of dilution/rinse water checked for sterility by adding 50ml of water to 50ml of double-strength non-selective broth. Incubate for 24 hours at 35oC and check for growth.

42. Laboratory Media Preparation Records Should Include : Date of preparation Type of medium Lot number Sterilization time and temperature Final pH Technician’s initials Each new batch of laboratory prepared medium checked before use with positive and negative culture controls and results recorded.

43. Thank You