Biochemical properties, resistance, antigens and toxins

BIOCHEMICAL PROPERTIES, RESISTANCE, ANTIGENS AND TOXINS

Biochemical properties

  • All the Listeria species hydrolyse aesculin, Catalase +ve, Oxidase –ve, Indole –ve.
  • They produced acid from glucose and rhamnose, but not from xylose and mannitol. Nitrates not reduced.

Resistance

  • It is killed by moist heat at 55°C for 40 minutes and is readily susceptible to the lethal effects of disinfectants.
  • Under natural conditions, in summer they survive for 1 month and in winter for 3-4 months.

Antigens and toxins

  • Based on somatic and flagellar antigens, so far 16 serovars have been identified.
  • Of these 16 serovars, all cases of animal and human infections are caused by 3 serotypes. ½ a, ½ b and 4 b.
  • Numbers indicate O antigen and alphabet indicate H antigens.
Last modified: Monday, 4 June 2012, 4:48 AM