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Corynebacterium & Bacillus - Microscopic appearance - Colonial morphology.

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Presentation on theme: "Corynebacterium & Bacillus - Microscopic appearance - Colonial morphology."— Presentation transcript:

1 Corynebacterium & Bacillus - Microscopic appearance - Colonial morphology

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3 Corynebacterium diphtheriae - Nasal, nasopharyngeal and tonsillar diphtheria.

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6 Corynebacterium diphtheriae - Cutaneous diphtheria.

7 Corynebacterium diphtheriae - Throat, nasopharyngeal swabs. - Skin swab.

8 Corynebacterium diphtheriae - Gram positive pleomorphic, long, thin, and curved forms can be seen and also short rods and rods enlarged at one end (clubshaped).

9 Corynebacterium diphtheriae - They often appear in clusters, joined at angles like Chinese letters.

10 - C. diphtheriae often appears beaded due to the presence of dark staining granules in the rods. -These granules, known as volutin or metachromatic granules, are energy-storing inorganic polyphosphate units. In some strains the granules form at the ends of the rods. - The granules are most numerous after the organism has been cultured on a protein-rich medium such as Dorset egg or Loeffler serum. Albert Staining of volutin granules

11 1- Fix the dried smear using alcohol. 2- Cover the smear with the toluidine blue malachite green stain for 3–5 minutes. 3-Wash off the stain with clean water. 4- Tip off all the water.

12 Albert Staining of volutin granules 5- Cover the smear with Albert’s iodine for 1 minute. Wash off with water. 6- Wipe the back of the slide clean, and place it in a draining rack for the smear to air-dry. 7- Examine the smear microscopically to look for bacteria containing metachromatic granules

13 Albert Staining of volutin granules Bacteria cells Pale green Metachromatic granules Green-black

14 Corynebacterium diphtheriae - They often appear in clusters, joined at angles like Chinese letters.

15 Tinsdal medium:- grey-black raised colonies surrounded by a dark brown area.

16 -Brown colour due to formation of H 2 S which result from interaction between cystine and tellurite.

17 C. diphtheriae grows rapidly on these media, producing significant growth in 4–6 hours.

18 Bacillus

19 Bacillus anthracis

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21 - Cutaneous ANTHRAX.

22 Bacillus anthracis - Pulmonary ANTHRAX.

23 Bacillus anthracis - Enteric ANTHRAX. - Meningoencephalitis.

24 B. anthracis is a high risk infectious pathogen, therefore handle specimens and infected material with care, wearing protective gloves and face mask, and following recommended safety procedures.

25 Bacillus anthracis - Fluid aspirated from cutaneous lesions. - Sputum. - Blood for culture. - CSF.

26 large, 5–8 X 1.5 μm, Gram positive, non-motile bacillus, often appearing joined end to end in chains

27 In smear from Specimens:- Bacilli are capsulated. The capsular material often appears irregular and fragmented

28 In smears from aerobic cultures: Bacilli are non-capsulated but contain oval spores (same diameter as the bacilli), giving the organisms a beaded appearance. They occur in chains.

29 Fixation of smears:- B. anthracis is not killed by heat-fixation. Smears should be chemically fixed by immersing the dry smears in a container of potassium permanganate solution for 10–15 minutes.

30 Bacillus anthracis Blood agar:- large grey-white 2-5 mm in diameter irregular with wavy edges colonies (non or slightly haemolytic).

31 Bacillus cereus - Food poisoning. - Opportunistic infections in immunocompromised persons (bacteraemia, pnumonia and wound infection).

32 Bacillus cereus Blood agar:- large grey-white 2-5 mm in diameter irregular with wavy edges haemolytic colonies.

33 B.cereus rapidly liquefies the gelatin along and out from the line of inoculation.


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