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Quality Control for Microbiological Culture Media

Quality Control for Microbiological Culture Media. Dr maryam Sotoudeh Tehran heart Center. Categories of Microbiological Media. Media are divided into two main descriptive categories based on the purposes for which the media were designed : . Selective . Non selective (nutritive).

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Quality Control for Microbiological Culture Media

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  1. Quality Control for Microbiological Culture Media Dr maryamSotoudeh Tehran heart Center

  2. Categories of Microbiological Media Media are divided into two main descriptive categories based on the purposes for which the media were designed : Selective Non selective (nutritive)

  3. Categories of Microbiological Media Nonselective media promote the growth of organisms Selective media contain antimicrobial or chemical agents that inhibit the growth of certain microorganisms Some nonselective and selective media also contain components that allow for organism differentiation.

  4. An NCCLS national consensus standard (M22-A3) Commercial media are divided into two additional categories, according to which are determined by quality control performance data collected by CAP(1984, 1988, 2001) • Exempt • Nonexempt

  5. Reasons Given for Lot Failures

  6. Exempt and Nonexempt Categories for Media Included in CAP Surveys (1984, 1988, 2001) (From Jones RN, Krisher K, Bird DS, and the College of American Pathologists Microbiology Resource Committee. Results of the survey of the quality assurance for commercially prepared microbiology media. Arch Path Lab Med. 2003;127(6):661-665

  7. User Quality Control Requirements for Nonexempt Media Only

  8. Visual Inspection Satisfactory UnSatisfactory 1.Cracked/damaged petridish 2. Agar dislodged or loose 3. Hemolysis of blood in medium 4. Color differs from characteristic appearance(possible pH problem) 5. Excessive accumulation of moisture 6. Evidence of freezing or medium desiccated 7. Gross contamination 8. Uneven or under filled plates/agar desiccation 9. Excessive bubbles/rough surface 10. Presence of precipitates 1. Intact petri dish 2. Agar attached to bottom of dish 3. Blood containing medium is opaque 4. Medium is appropriate color 5. Minimal moisture in package 6. Not frozen or desiccated 7. No visible contamination 8. Agar has even depth of at least 3 mm 9. Smooth agar surface 10. No precipitates

  9. Sterility Check • For Sterility checking of a lot : • In batch of 100 or fewer units : 5% of any lot • In larger batch : a maximum of 10 units are tested Baily and scott’s

  10. Sterility Check

  11. Inoculumpreparation for aerobic/anaerobic bacteria: Prepare a suspension of a 24-hour culture in sterile saline to match a 0.5 McFarland standard. (Primary Suspension) (PS). Acceptable performance should generally allow initiation of routine testing within 24-48 h for nonfastidious, more rapidly growing bacteria

  12. Preparation of Suspensions for Quality Control of Nonexempt Media

  13. for Nonselective Media If the 1:100 dilution inoculum proves too dense,use a 1:1000 dilution to produce isolated colonies. • for selective Media Use a 1:100 dilution if isolated colonies are not produced

  14. Minimum requirements for media quality control include at least one organism to document support of growth. Testing additional organisms is recommended to confirm the performance of inhibitory or selective media

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