Coagglutination test in the diagnosis of typhoid fever

Staphylococcal coagglutination (CoA) test for the detection of Salmonella typhi O (factor 9) antigen was evaluated as a diagnostic test in typhoid fever. Supernatants from 106 blood cultures with Gram negative bacilli were subjected to CoA test. The sensitivity of the CoA test for the detection of S. typhi O antigen was 88 per cent and the specificity 97 per cent.