Thursday, 19 March 2015

Bacterial stains

Bacillus anthrax : it is a gram + bacilli in bamboo stick or box car shape. on staining with polychrome methylene blue it shows MAC FADYEANS reaction which represent capsular material [ AiiMS 04,06,07].

Corynebacterium diptheriae : is a gram positive non motile rod. it contains granules called as Babes Ernst /volutin granules which r more strongly gram + . on staining with loeffers methylene blue granule shows metachromatism( AIIMS 07, PGI 2000). special stains to see granules are ALBERT, NEISSER,PONDER (JIPMER03).

MYCOBACTERIUM TUBERCULOSIS: ZN STAIN is used and it is acid fast. Auramine Rhodamine stain in which organism show reddish yellow fluorescence is used in  fluorescent microscopy( this is more sensitive than ZN staining).

NON LACTOSE FERMENTATER : ie colourless on mac conkey agar ; shigella ( except s. sonnei) . salmonella, proteus.

CHOLERA RED REACTION : it is due to nitrate reduction & sucrose ferfentation in v.cholerae

YERSINEA PESTIS : bipolar safety pin appearance with WAYSON STAIN (AI 2006), GIEMSA,  METHYLENE

T.PALLIDUM: silver impregnation method by using warthin starry silver stain. Fontana method is for staining  films and levaditi for tissue sections.

MYCOPLASMA: Colony is biphasic with “fried egg appearance”. when stained by. dienes method (PGI 95, 99)

CRYPTOCOCCUS NEOFORMANS:  it has polysaccharide capsule which is stained by india ink preparation. This is method of choice for detecting crypto in csf.(AI05,PGI 02)

FUNGAL STAIN: best ( most sensitive) fungal stain is gomori methamine silver stain. Best stain for fungal detection in biopsy sample is PAS ( Aiims 06)

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