Bactericidal activity of human sera against Salmonella typhi and Salmonella paratyphi A, B, C.

Objectives: To determine the sensitivity of Salmonella typhi and paratyphi A,B,C, to normal human blood serum; and assess the role of blood groups (ABO system), Complement and Immunoglobulin in the resistance or susceptibility of Salmonella typhi and Salmonella paratyphi A,B,C infections. Design: Cross sectional study. Subjects: Ninety-six apparently healthy males and females volunteers,aged 18-24 years. Main outcome measures: Resistance of Salmonella typhi and Salmonella paratyphi A,B,C infections may be blood group and immune status dependent. Results: Blood group B was most resistant to Salmonella typhi and Salmonella paratyphi A,B,C while blood group O showed least resistance (51.9%) and (22.2%) for Samonella typhi and Salmonella paratyphi A,B,C, There was no difference in resistance pattern when blood was pooled in respect to their group types. Age or sex of the blood donors had no effect on the bactericidal activity of the sera. Conclusion: Blood group is an inportant factor in the susceptibility or resistance of an individual to Salmonella typhi and paratyphi infections. Individuals of blood group O are likely to be more susceptible to infections caused by Salmonella typhi and paratyphi A,B,C.