The Nagler test

موضوع: The Nagler test الخميس أغسطس 28, 2008 7:01 pm

....السلام عليكم ورحمة الله وبركاته....

……The Nagler test……

The Nagler test: is principally used for the differentiation of Clostridium perfringens from other
members of the genus Clostridium by neutralisation of lecithinase C by a specific antitoxin.

يستخدم هذا الفحص في التفريق بين Clostridium perfringens عن باقي spps الأخرى ,معتمدا على قدرة هذه البكتيريا في إنتاج مادةlecithinase C ...

§ Clostridium baratii, Clostridium absonum,
Clostridium bifermentans, Clostridium sordelli and
Clostridium novyi also produces lecithinase.

§ Clostridium baratii and Clostridium absonum
may produce a partial cross reaction with the antitoxin
, if a heavy inoculum of the organism is used.

§ C. Sordelli and C. bifermentans are also closely
related to C. perfringens alpha toxin (leathinase) and can produce a partial cross-reaction.

Principle of the test:
Bacterial lecithinase breaks down
lecithin(a normal component of egg yolk) to insoluble
diglycerides, resulting in an opaque halo surrounding
the colony when grown on egg yolk agar.

تنتج البكتيريا مادة lecithinase والتي تكسر مادة lecithin
الموجودة في الوسط (وهي مكون طبيعي في صفار البيض)فتحوله إلى
Insolublediglycerides مما ينتج عنه منطقة شفافة (بيضاء) (opaque) تحيط بالبكتيريا .

Although the test is mainly used for the
differentiation of the Clostridium species, the demonstration
of lecithinase production is useful for the division of
the genus Bacillus.

Procedures and results:
1. Inoculate half the egg yolk agar plate with 60μL
antitoxin. Spread with a ‘hockey stick’spreader or 10 μL
loop and allow to absorb and dry.
2. Mark which side of the plate has been inoculated with
the antitoxin.
3. Streak the test organism in a straight line from the
antitoxin free half across to the antitoxin side
of the plate.
4. Inoculate the control organisms in the same manner
on the same plate.
5. Incubate anaerobically at 35-37°C for 24-28h.
6. Examine the plate for an opalscent halo around the
inoculum and inhibition by antitoxin.

Positive result:
Disappearance or marked reduction of the opacity on the
Antitoxin half of the plate (denoting neutralisation of the lecithinase).

Negative result:
No disappearance of the opacity on the antitoxin half
of the plate.

.....المصادر:
http://www.hardydiagnostics.com/catalog2/hugo/EggYolkAgar.htm
http://www.answers.com/topic/nagler-s-reaction
http://www3.interscience.wiley.com/cgi-bin/fulltext/120047071/PDFSTART?CRETRY=1&SRETRY=0
http://images.google.com/imgres?imgurl=
http://content.answers.com/main/content/wp/en/thumb/6/63/240px-Clostridium_perfringens_01.png&imgrefurl=http://www.answers.com/topic/clostridium-
perfringens&h=167&w=240&sz=53&hl=ar&start=6&tbnid=KRsOkomGtVwaUM:&tbnh=77&tbnw=110&prev=
/images%3Fq%3DNagler%2Breaction%26gbv%3D2%26hl%3Dar%26sa%3DG
http://images.google.com/imgres?imgurl=
http://teaching.path.cam.ac.uk/Microbiology/BI_Bacteriology/CL_Clostridia/M_BI_CL_27.jpg&imgrefurl=
http://teaching.path.cam.ac.uk/partIB_pract/P19/&h=
709&w=701&sz=264&hl=ar&start=1&tbnid=2-4fUBYKe6SoEM:&tbnh=140&tbnw=138&prev=
/images%3Fq%3DNagler%2Breaction%26gbv%3D2%26hl%3Dar%26sa%3DG.

تحياتي

موضوع: رد: The Nagler test الجمعة أغسطس 29, 2008 10:24 pm

بارك الله فيكي. الفحص مهم كثير و أعتقد انه فكرة جيدة ان نولي موضوع الفحوصات المستخدمة للتفريق بين الأنواع المختلفة من البكتيريا اهتماما خاصاً في هذا المنتدى. للاسف سأكون مشغولاً جداً في الفترة القادمة و لا أدري ان كنت سأستطيع المشاركة في مثل هذا الموضوع و لكني أشجع جدا الفكرة

مع التحية

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موضوع: رد: The Nagler test السبت أغسطس 30, 2008 8:40 pm

وفيك بارك الله ....
وشكرا دكتور لمرورك....