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ممكن تساعدوني على اختبار coagulase

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  • ممكن تساعدوني على اختبار coagulase

    السلام عليكم ورحمة الله وبركاته..

    اخواني وخواتي.. كيفكم ان شاء الله بكامل عافيتكم يارب..

    اختبار coagulase ..

    كيفيه تحضير هذا الاختبار بوجود مادة تدعي EDTA وهي مادة تمنع تجلط الدم ويستخدمونها بالمستشفي

    و كم وزن الEDTA الازمه لى اجراء هذا الاختبار؟؟

    الف شكر لكم والله يوفقكم اى مايحبه الله ويرضاء

  • #2
    Coagulase Test

    Slide Coagulase Test
    Coagulase is a thermostable enzyme found primarily in S. aureus and is used to differentiate S. aureus from other commonly isolated staphylococci. Two forms of coagulase exist: one is bound to the cell wall, and one is liberated by the cell as “free coagulase.” Slide coagulase test detects the bound coagulase (clumping factor), which acts directly on the fibrinogen in plasma and causes clumping of bacteria. Slide coagulase test results agree approximately 96% with tube coagulase test results. Coagulase-positive organism forms clumps within 10 s, but coagulasenegative organism remains uniformly suspended.
    Using a sterile pipette, a drop of sterile saline is placed on a glass slide. One to two colonies of the organism is emulsified in the saline and tested for autoagglutination.
    A drop of rabbit plasma is placed on the slide and mixed for few seconds and observed for clumping within 10 s.
    A positive slide coagulase test result is valid only for strains of Staphylococcus spp. that are negative for autoagglutination or stickiness. Coagulase is also present
    in S. intermedius and S. hyicus, but these species are infrequent clinical isolates. Similarly, clomping factor is produced by S. scheiferi and S. lugdunensis and may
    give false-positive reactions (Isenberg, 1992; Koneman et al., 1997)

    Tube Coagulase Test
    Tube coagulase test detects free coagulase (liberated by the cell) that acts on prothrombin to produce a thrombin-like product that then acts as fibrinogen to form a fibrin clot.
    Prepare a heavy suspension of the Staphylococcus colonies in 0.5 mL of water. Place the suspension into a tube containing rabbit plasma and incubate at 35◦C for
    4 h. Examine for the presence of a clot. If negative for a clot, reincubate the tube and reexamine at 24 h. Any degree of clot formation at 4 h or 24 h is considered
    a positive reaction. No clot formation at 24 h is considered negative coagulase
    reaction (Koneman et al., 1997; Forbes et al., 2002; Murray et al., 2003).
    .
    http://www.7ammil.com/data/visitors/...618_p1052h.jpg

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    • #3
      coagulase

      Principles
      Coagulases are enzymes that clot blood plasma by a
      mechanism that is similar to normal clotting. Although
      coagulase activity is not required for pathogenicity,
      this enzyme is a good indicator of the pathogenic potential of S. aureus. Coagulase-producing staphylococci (termed coagulase positive) form a fibrin clot around themselves and avoid attack by the host’s defenses.
      In the coagulase test, coagulasepositive staphylococci will cause the plasma to clot by using coagulase to initiate the clotting cascade. Citrate
      and EDTA are usually added to act as anticoagulants
      and prevent false-positive results. Cultures should be
      considered coagulase negative if they are unclotted
      after 4 hours.

      Coagulase Test
      1. Add 0.5 ml of citrated rabbit plasma to two
      small test tubes. With the wax pencil, label the
      tubes with the respective bacteria, your name,
      and date.
      2. Inoculate one tube with enough S. aureus paste to
      make a cloudy suspension. Inoculate the other
      tube with S. epidermidis. Alternatively, one can
      add about 5 drops of thick 18- to 24-hour broth
      culture to each tube.
      3. Incubate both tubes at 35°C for 1 to 4 hours in a
      water bath. Afterward, examine both tubes for the
      presence or absence of clouding and clots.

      A positive coagulase test is represented by any
      degree of clotting, from a loose clot suspended in
      plasma to a solid clot.
      http://www.7ammil.com/data/visitors/...618_p1052h.jpg

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      • #4
        السلام عليكم و رحمة الله و بركاته

        عندى استفسار بسيط هل من الممكن ان نستخدم human plasma ام ان الاختبار مقتصر على rabbit plasma فقط

        و جزاكم الله خيرا

        " حينمــا يفتخــر الناس بحســن كلامهــم

        ,,,,,,,, افتخــر أنا بحســن الصــمت " .

        MR HIDE

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        • #5
          The plasma used in the coagulase test may be fresh human or rabbit plasma
          obtained with ethylenediamine tetraacetic acid (EDTA). It should be stored in the refrigerator in small amounts (1 ml), and its performance checked with
          cultures of S. aureus and S. epidermidis, run in parallel.
          WHO2003
          http://www.7ammil.com/data/visitors/...618_p1052h.jpg

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          • #6
            وعليكم السلام ورحمة الله وبركاته
            اخي في الله الاختبار يمكن ان يجرى باستخدام بلازما الانسان اذا لم تتوفر بلازما الارنب وعندنا في احد المستشفيات يستخدمون بلازما انسان واظن هذا الشيء في باقي المستشفيات ايضا
            وكما وضحت في الفقرة السابقة الماخوذة من احدى منشورات منظمة الصحة العالمية
            شكرا على المرور الطيب
            http://www.7ammil.com/data/visitors/...618_p1052h.jpg

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            • #7
              life science you have to be a teacher you are so good in giving information in a clear and organized way. thank you

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              • #8
                Everybody
                You Are Welcome
                http://www.7ammil.com/data/visitors/...618_p1052h.jpg

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                • #9
                  there is a question is still

                  which plasma is prefered to use the EDTA or citrated one

                  thanks alot for the information dear

                  " حينمــا يفتخــر الناس بحســن كلامهــم

                  ,,,,,,,, افتخــر أنا بحســن الصــمت " .

                  MR HIDE

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                  • #10
                    oxalated or citrated plasma

                    Difco and BBL recommend to use EDTA plasma because it does not utilizing by some bacteria and eliminate false positive coagulation of plasma by citrate-utilizing bacteria
                    but you can use oxalated or citrated plasma for this test as I did
                    http://www.7ammil.com/data/visitors/...618_p1052h.jpg

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                    • #11
                      thanks alot life science you are so useful

                      " حينمــا يفتخــر الناس بحســن كلامهــم

                      ,,,,,,,, افتخــر أنا بحســن الصــمت " .

                      MR HIDE

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                      • #12
                        ما شاء الله عليك ياlife science كلام جميل وموزون والا الامام

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                        • #13
                          العفو منكم انتم اساتذتي وحافزي للتقدم ان شاء الله
                          ربي يوفق الجميع
                          http://www.7ammil.com/data/visitors/...618_p1052h.jpg

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