Novel haemolysins of <i>Salmonella enterica </i>spp. <i>enterica </i>serovar Gallinarum

Abstract

Haemolysins of <i>Salmonella </i>are important due to their probable role in pathogenesis of systemic salmonellosis and use in sub-serovar level typing. The present study was undertaken to determine haemolytic potential of <i>Salmonella </i>Gallinarum strains through phenotypic and genotypic methods. Amplification of haemolysin gene (<i>cly</i>A)<i> </i>and cytolysin gene (<i>sly</i>A)<i> </i>was

attempted in order to determine their role in haemolysin production. Study on 94 strains of <i>S</i>. Gallinarum revealed the production of two types of haemolysis <i>viz., </i>beneath the colony haemolysis (BCH) or contact haemolysis and clear zone haemolysis (CZH). Haemolysis was observed on blood agar prepared with blood of cattle, buffalo, sheep, goat, horse, rabbit,

guinea pig, fowl, and human blood group A, B, AB and O. Although, haemolysis was also observed on blood agar prepared with whole blood, clarity of zone was more evident on blood agar made from washed erythrocytes. Clear zone haemolysis was best observed on blood agar prepared with washed erythrocytes of goat and a total of 12% (11 of 94) <i>S</i>. Gallinarum strains under study produced CZH on it. The <i>cly</i>A<i> </i>gene could not be detected in any of the 94 strains under study, while <i>sly</i>A<i> </i>gene could be amplified uniformly irrespective of haemolytic potential (CZH) and haemolytic pattern (BCH) of the strains. The study suggested that the two types of haemolysis (CZH and BCH) observed among <i>S</i>. Gallinarum strains may not be due to either <i>slyA </i>or <i>clyA </i>gene products and thus there may be some other gene responsible for haemolytic trait in Gallinarum serovar. Different haemolytic patterns of strains under study indicated multiplicity of haemolysins in <i>S</i>. Gallinarum