تويت
Corynebacterium diphtheriae: bacteria gram positive bacilli Non Acid Fast or None Spore
Characteristics
Habitat
Transmission
Pathogenesis
Diseases
Laboratory Identification
Diagnosis
in order to accurately identify C. diphtheriae, a Gram stain is performed to show gram-positive, highly pleomorphic organisms with no particular arrangement. Special stains like Alberts’s stain and Ponder’s stain are used to demonstrate the metachromatic (metachromacity is the phenomenon by which different parts of an organism can get stained in two or more different colours just by applying a single dye) granules formed in the polar regions. The granules are called as polar granules, Babes Ernst Granules, Volutin, etc.). An enrichment medium, such as Löeffler’s serum, is used to preferentially grow C. diptheriae
source :http://laboratory-testing.org/Characteristics
- Gr+ Ve Polymorphic bacilli (club-shaped) .
- cells appear in chineses-letter arrangement .
- non capsulate , non sporing , non motile .
- Facultative anaerobes .
- Ferment carbohydrate .
- Most grow well in lipid free media .
Habitat
- Nasopharynx & occasionally skin of human
Transmission
- droplets spread
- direct contact
Pathogenesis
- Diphtheria exotoxin = block protein synthesis
- Unknown Virulance Factors.
Diseases
- diphtheria
- localized inflammation of the throat
- infecting organisms do not invade but rather elaborate an exotoxin that spreads through blood
- pharynx , larynx , & nose are main sites
- pseudo – membrane is formed & may lead to respiratory obstruction
- mainly affecting infants over 1 year old children & young adults
- Endocarditis
Laboratory Identification
- [*=left]Specific media for C.diphtheria :-
- 1- cysteine tellurite agar
- 2- serum tellurite agar .
- back colonies on blood tellurito agar
- Use loeffler medium to recover C.diphtheria .
- detection toxin by Elek test .
- teelurite inhibit growth of most upper respiratory bacteria and gram negative rods .
Diagnosis
in order to accurately identify C. diphtheriae, a Gram stain is performed to show gram-positive, highly pleomorphic organisms with no particular arrangement. Special stains like Alberts’s stain and Ponder’s stain are used to demonstrate the metachromatic (metachromacity is the phenomenon by which different parts of an organism can get stained in two or more different colours just by applying a single dye) granules formed in the polar regions. The granules are called as polar granules, Babes Ernst Granules, Volutin, etc.). An enrichment medium, such as Löeffler’s serum, is used to preferentially grow C. diptheriae
في كلمه غلط .. بالموضوع تتشفر تلقائي بسبب الحمايه الي هي e t c وهذا معروف انه مجلد في root في الليونكس , الافضل انه لاينمع الكلمات صاحب الموقع لان ماله دخل مره بالامور هذي ,,الحمايه في المنتدى , انا مستعـد أثبت له هذه النظريه , مابي أغير الموضوع , بالتوفيق ,