The use of active melioidosis detect in early diagnosis of melioidosis in Hospital Ampuan Afzan and Hospital Sultanah Nurzahirah

Abstract

INTRODUCTION: Melioidosis is endemic in Malaysia and an important cause of pneumonia and sepsis. Current gold standard for diagnosis is by culture method, but its long procedure will delay the treatment leading to hospital-related mortality. Thus, a good rapid test is needed for early diagnosis to guide the treatment and reduce its mortality burden. Recently, Lateral flow immunoassay (LFI) called Active Melioidosis Detect™(AMD) have been shown to be useful in the early diagnosis of melioidosis especially if tested on body fluids. OBJECTIVES: (1) To measure the sensitivity and specificity of AMD for diagnosis of melioidosis. (2) To study the sensitivity and specificity of early morning urine AMD compared to spot urine AMD in the initial diagnosis of melioidosis. METHOD: This is a prospective cross-sectional study of clinically suspected melioidosis patients in HTAA Kuantan and HSNZ Kuala Terengganu from April until December 2018. Blood and urine samples were taken from patients who fulfilled the selection criteria and tested with AMD. Test results were analysed for sensitivity, specificity, positive predictive value and negative predictive value with culture as the gold standard method of melioidosis diagnosis. RESULTS: A total of eighty-nine patients were included in this study.The mean age of the patients is 52 years old, and 56.3% were male gender. 64% of suspected melioidosis patients have diabetes mellitus. 11 patients have positive blood culture for Bukholderia pseudomallei, 4 of them were tested positive for AMD (blood or urine). 3 of them presented with septic shock (3.4%), however none died. 25 patients with culture negative tested positive AMD.The sensitivity of the AMD was 36.4% ([95% CI 12.4 to 68.4]) and the specificity was 66.7% ( [95% CI 46.0 to 82.8]) in all samples, with positive predictive value of 30.7% and negative predictive value of 72%. Blood samples have lower sensitivity of 9.1% ([95% CI 4.8 to 42.9]) with high specificity of 100% ([95% CI 84.5 to 100]). Urine spot samples have higher sensitivity compared to serum, with 36.4% ([95%CI 12.4 to 68.4]) and specificity of 88.9% ([95% CI 69.7 to 97.1]). Morning urine samples have sensitivity of 33.3% ([95% CI 9.1 to 69.1]) and specificity 66.7% ([95% CI 43.1 to 84.5]). CONCLUSION: From this pilot study, this test requires further evaluation before incorporating its use as point of care assay. Although it has limited sensitivity in serum samples, urine spot is more sensitive than plasma, with high specificity.