1. QUALITY CONTROL IN MEDICAL MICROBIOLOGY Quality control is divided into: @ Internal quality control: performed locally inside lab. @ External quality control: performed between district labs. in same country or worldwide.

2. Discussing quality control programs

3. Areas of Quality Control: @ Specimen collection & transport. @ Culture media. @ Sensitivity techniques @ Stains & reagents. @ Equipment. @ Reporting & recording results.

4. Culture media

5. Control of Sample Collection & Transport: @ Define the correct specimen to collect. @ The best time to collect. @ Aseptic method for collection. @ Best methods of storage and transport @ How to handle specimens in lab., e.g. blood cultures, CSF, urine, swabs, stool, wet slide preparations.

6. Sample Collection

7. Control of Culture media: @ Perform correct pH testing, correct storage, and correct autoclaving. @ Standard control species are used for test performance of media @ No moisture to enter powder media @ Caps are replaced quickly & tightly. @ Store plates at 4 °C in plastic bag. @ Before use, dry surface of plates.

8. Correct autoclaving

9. @ Do not leave unused plates on bench overnight to avoid contamination. @ Slope media & fluid media may be stored at room temp. if screw-capped @ New batches of media are dated and stored separate from old batches. @ Shelf-life of each medium is noted. @ Small batches of media are prepared to avoid waste.

10. Media ready for incubation

11. Trouble-Shooting for Media @ Defective media: * Use good quality media @ Incorrect weighing: * Check and correct the mistake. @ Deteriorated media: *Store media in airtight containers at the appropriate temperature @ Bad water : * Use distilled water for media preparation.

12. Use good quality media

13. @ Undissolved media: * Dissolve powder by mixing & boiling. @ Overheating of media after autoclaving: * Open autoclave when pressure comes down & temperature is below 100°C * Cool media immediately after autoclaving. @ Incorrect pH of medium: * Measure pH when medium cools to room temp. * Pour a sample of medium in a beaker, let agar to solidify around the electrode, and read pH.

14. pH meter

15. Antimicrobial Susceptibility Tests Control cultures : S. aureus ATCC 25923 (miscellaneous) E. coli ATCC 25922 (urine) P. aeruginosa ATCC 27853(Ps.) @ Subcultured weekly & stored in Fridge. @ To detect inhibitors in MH agar, inoculate E.faecalis (ATCC 29212),put co-trimoxazole disc and inhibition zone must be ≥ 20 mm

16. Antimicrobial Susceptibility Te sts

17. Sources of Error in Sensitivity Testing (1) Too small control zones: Due to: @ Use of discs with low potency @ Use of discs after expiry date. @ Use of a too dense inoculum @ Use of too thick medium layer @ Presence of inhibitors MH agar medium

18. Too small zones

19. (2) Too large control zones: Due to: @ Use of discs with high potency. @ Use of a too diluted inoculum @ Use of a too thin medium layer (3) Presence of colonies within inhibition zones: Due to: @ Contamination of culture (large colonies) @ Presence of inhibitors in MH agar (small colonies) detected by co-trimoxazole

20. Too large zones

21. Control of stains & reagents : @ A @ A control smear is stained to check quality of newly-made stains @ Control smears of gram stain is made from a mixed culture of Staph & E.coli @ Control smears are kept in lab. to check Z.N, Leishman, spore stains, etc @ Control smears should be alcohol-fixed

22. Control smears of Gram stain

23. Control of equipment: @ Regular servicing & maintenance @ Check glassware for good condition @ Inspect tube caps and worn liners. @ Regular check of working temp. @ Check water of water-bath, etc @ Use of indicators to check autoclaves, anaerobic jar, etc @ Check distilled water.

24. Regular check of incubator working temp

25. Control of Results: @ Printed forms or computer sheets must be used for reporting results. @ Result must be typed clearly and checked by a senior lab. staff. @ Copies of all results are kept in lab. @ Dates, demographical data, type of specimen & technologist name must be included.

26. Typing laboratory res ults