RESUMO
Two lipopolysaccharide antigens that differ by the technique of preparation from S. typhi, one named crude is easily extracted, the other one is water-phenol extracted. Both were adsorbed by papain and cysteine to lamb erythrocyte surfaces, fixed then by glutaraldehyde and used in a plate microhemagglutination test (MHA). The MHA test was done with 30 sera from children with S. typhi blood isolates. The same number of control sera were tested for comparison. The crude LPS antigen showed better sensitivity: 73% versus 53% of the water-phenol extracted one despite a high index correlation (r = 0.88). The latest one was evaluated in a prospective study, using it during a six-month period in an emergency room with S. typhi blood isolated sera. The MHA test was compared with the surface fixation test. Both assays showed similar sensitivity and a specificity of 91 and 100%, respectively.
Assuntos
Febre Tifoide/imunologia , Adolescente , Criança , Pré-Escolar , Feminino , Testes de Hemaglutinação/métodos , Humanos , Lipopolissacarídeos/imunologia , Masculino , Salmonella typhi/imunologia , Febre Tifoide/sangueRESUMO
Using a capillary flocculation technique we evaluated serum samples of asymptomatic children for typhoid fever serology. Thirty one (5.16%) of the 600 serum samples tested were positive for a specificity of 95%. To evaluate the sensitivity of the test, serum samples from 36 children with proven typhoid fever and a similar number of control patients were evaluated. The sensitivity of the capillary flocculation test in this group was 100%. The test compared favorably with the Ruiz Castañeda serologic test for typhoid fever.