Deteksi IGM terhadap Antigen Lipopolisakarida (LPS) O9 Kuman Salmonella Typhi pada Demam Tifoid

Abstract

Background: Typhoid fever is a systemic infectious disease caused by Salmonella typhi. That is still widely found in many developing countries that are mainly located in the tropical and subtropical. Clinical diagnosis of typhoid fever is difficult because there is no typical clinical manifestation, therefore we need laboratory tests. IMBI (Magnetic Binding Inhibition Immunoassay) is one of serological examination or it more popularly known as Tubex TF, a semi-quantitative examination with the principle of detecting the presence of IgM antibodies of O9 lipopolysaccharide antigen in Salmonella typhi. Objective: To assess the sensitivity and specificity of the IgM antigen examination of Salmonella typhi O9 lipopolysaccharide (LPS) with blood culture as the gold standard Methods: The method that was used in this study was diagnostic testing to compare Tubex TF with blood cultures in pediatric and adult patients who were diagnosed with suspected typhoid fever or typhoid fever based on Nelwan criteria in Haji Adam Malik Hospital. Results: The number of subjects are 30 people, with 27 positive Tubex TF (90%) and 12 positive blood cultures (40%). The examination results of Tubex TF towards blood culture showed 100% sensitivity, 16,7% specificity, 44,4% positive predictive value and 100% negative predictive value. Conclusion:The results of Tubex TF serology test showed a good sensitivity and a poor specificity, with a negative predictive value of 100% which indicates that a negative Tubex TF examination can rule out the diagnosis of typhoid fever.

Latar Belakang : Demam tifoid merupakan suatu penyakit infeksi sistemik yang disebabkan oleh Salmonella typhi. Masih dijumpai secara luas diberbagai negara berkembang terutama terletak didaerah tropis dan subtropis. Diagnosa klinis demam tifoid sulit ditegakkan karena manifestasi klinisnya tidak khas, maka diperlukan pemeriksaan laboratorium. Salah satu pemeriksaan serologi adalah pemeriksaan metode IMBI (Immunoassay Magnetic Binding Inhibition), atau lebih populer dengan nama dagang Tubex TF, suatu pemeriksaan semi kuantitatif dengan prinsip mendeteksi adanya antibodi IgM terhadap antigen lipopolisakarida O9 pada kuman Salmonella typhi. Objektif : Menilai sensitivitas dan spesifisitas pemeriksaan IgM terhadap antigen lipopolisakarida (LPS) O9 kuman Salmonella typhi dengan kultur darah sebagai gold standart Metode : Metode yang digunakan dalam penelitian ini adalah uji diagnostik membandingkan Tubex TF dengan kultur darah pada pasien anak dan dewasa yang terdiagnosa suspek demam tifoid atau demam tifoid berdasarkan kriteria Nelwan di RSUP Haji Adam Malik Medan. Hasil : Subjek penelitian berjumlah 30 orang, dengan Tubex TF positif 27 orang (90%) dan kultur darah positif 12 orang (40%). Dari hasil pemeriksaan TF terhadap kultur darah didapatkan sensitivitas 100% dan spesifisistas 16,7% serta nilai prediksi positif 44,4% dan nilai prediksi negatif 100%. Kesimpulan : Dari hasil penelitian didapatkan uji serologi Tubex TF memiliki sensitivitas yang baik dan spesifisitas yg kurang baik, dengan nilai prediksi negatif 100% menunjukan pemeriksaan Tubex TF negatif dapat menyingkirkan diagnosa demam tifoid.