Recognition of virulence parameters in phospholipase A producing Salmonella

KAPOOR, S., D. K. SHARMA, S. SHARMA, M. S. KALRA: Recognition of virulence parameters in phospholipase A producing Salmonella. Vet. arhiv 76, 421-429, 2006. ABSTRACT Thirty-two strains of Salmonella belonging to six serovars were subjected to antimicrobial drug sensitivity, surface hydrophobicity assay, haemolytic activity assay, hydrolytic activity assay and enterotoxigenicity of enzyme phospholipase A. The five strains that produced phospholipase A were resistant to most of the antibiotics. Using various concentrations of ammonium sulphate for salt aggregation test, a high degree of correlation was observed between phospholipase A production and hydrophobicity. The strain S30 (Salmonella Enteritidis) producing the maximum phospholipase A was selected for studying the haemolytic and hydrolytic activities, as well as enterotoxigenicity of phospholipase A fractions. The intracellular fraction of the enzyme phospholipase A showed more haemolytic activity and hydrophobic activity than extracellular enzyme. The intracellular enzyme was non-haemolytic to sheep RBC’s but hemolyzed all other mammalian erythrocytes. Enterotoxigenic studies revealed maximal gut index with crude intracellular phospholipase A fraction (0.61) followed by crude extracellular fraction (0.57). The purified fractions of the enzyme showed mild to moderate gut reaction as compared to crude fractions, which gave moderate to marked reaction. The role of phospholipase A in exhibiting virulence has been discussed.