Product Code TM 068
The spectrum of disease caused by Clostridium difficile (a pathogenic Clostridium affecting the bowel) ranges from pseudomembranous colitis (PMC) through antibiotic associated colitis (AAC). It also includes chronic inflammatory bowel diseases, post-operative diarrhoea and non-antibiotic associated diarrhoea. Smith and King first reported the presence of C.difficile in human infections. George et al recommended the use of a fructose-containing medium with egg yolk for the isolation of C.difficile from faecal specimens. The medium was made inhibitory to the accompanying flora by the addition of the selective agents namely, D-cycloserine and cefoxitin. This medium does not contain neutral red indicator, as in the original formulation, as it is recommended for use with sheep or horse blood. Clostridium Difficile Agar Base is used for the primary isolation of C.difficilefrom faecal specimens. The medium composition is designed so as to obtain luxuriant growth of C.difficile. The selective agents D-cycloserine and cefoxitin used in the medium inhibit the growth of majority of Enterobacteriaceae and also Enterococcus faecalis, Staphylococci, gram-negative anaerobic bacilli and Clostridium species other than C. difficile, which may be found abundantly in faecal samples. Addition of 7% v/v horse blood to the base increases the recovery of C. difficile and also increases its colony size.
Spread a part of the faecal sample on the medium to obtain isolated colonies. Incubate the plates anaerobically at 37?C for 18 – 48 hours. C. difficile forms grayish white, irregular, raised and opaque colonies, 4-6 mm in diameter, after 48 hours. Typical gram stain morphology of C. difficile may not be seen in colonies taken from this medium due to the presence of antibiotics. Subculture on Blood Agar to obtain characteristic morphology. C.difficile colonies will not exhibit the typical fluorescence and colour of colony on this medium whereas other Clostridia can give fluorescence. Therefore, for complete identification and confirmation, other tests like gram staining, morphology, biochemicals, specific cytotoxin and clinical observation should be carried out.
for isolation of Clostridiffm diffcille from food and pathological specimens
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