Evaluation of Sensitivity and Specificity of ELISA and PBA for IgM Detection to LPS Antigen of Salmonella Typhi

Abstract

The high prevalence of typhoid fever in developing countries, including
Indonesia has prompted the exploration of various serologic tests and antigen detection
method to obtain an early and accurate diagnosis of patients with typhoid fever.
Although typhoid fever is confirmed by culture of Salmonella enterica serotype Typhi,
there is still an urgent need for the rapid, simple serological tests and evaluation of
effective and appropriate diagnostics for typhoid fever. In this study, we evaluated and 

compared the sensitivity and specifity of ELISA and Passive Bacterial Agglutination
(PBA) as an agglutination-based serological test to LPS antigen of Salmonella Typhi
and the effectiveness of local antigen in detecting the production of specific antibody
(IgM) to patient with typhoid fever. We collected serum sample of 50 suspected typhoid
fever from DR. Wahidin Sudirohusodo General Hospital, Daya General Hospital, Gowa
General Hospital and Kassi-Kassi Public Health Center in Makassar, South of Sulawesi.
They were grouped based on sex, duration of fever, and age. Serum antibody titer were
measured by ELISA and PBA. Data were analiyzed satistically by using cross tabulation
and chi-square (CI = 95%). The Result of this study showed that PBA technique has the
level of sensitivity and specifity respectively 100% and 92 %, while ELISA was 84% and
28%. It suggested that PBA has a greater level of sensitivity and specifity than ELISA.
We also showed that LPS antigen that we obtained from local isolate of Salmonella
Typhi, can be used as a standard antigen in diagnosing typhoid fever.