Biochemical properties, resistance, antigens and toxins
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Biochemical properties
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All the Listeria species hydrolyse aesculin, Catalase +ve, Oxidase –ve, Indole –ve.
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They produced acid from glucose and rhamnose, but not from xylose and mannitol. Nitrates not reduced.
Resistance
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It is killed by moist heat at 55°C for 40 minutes and is readily susceptible to the lethal effects of disinfectants.
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Under natural conditions, in summer they survive for 1 month and in winter for 3-4 months.
Antigens and toxins
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Based on somatic and flagellar antigens, so far 16 serovars have been identified.
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Of these 16 serovars, all cases of animal and human infections are caused by 3 serotypes. ½ a, ½ b and 4 b.
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Numbers indicate O antigen and alphabet indicate H antigens.
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Last modified: Monday, 4 June 2012, 4:48 AM