Detection of Pseudomonas pseudomallei Antigen in Urine for the Diagnosis of Melioidosis

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  • Faculty of Tropical Medicine, Mahidol University, Department of Clinical Sciences, London School of Hygiene and Tropical Medicine, Laboratory of Hospital Infection, Central Public Health Laboratory, Division of Medicine, Sappasitprasong Hospital, Nuffield Department of Clinical Medicine, John Radcliffe Hospital, Oxford University, Bangkok, Thailand

An enzyme-linked immunosorbent assay using a fluorescein isothiocyanate (FITC)-anti-FITC amplification system, has been developed to detect Pseudomonas pseudomallei antigen in urine. The assay was evaluated in 135 patients with acute melioidosis, 194 hospitalized patients with other disorders, and 40 healthy controls. Antigen was detected in the urine of 123 (91%) patients with melioidosis. Urinary antigen was found in 85 (96%) of 89 patients with septicemic melioidosis, all six patients with P. pseudomallei urinary tract infection, and 32 (80%) of 40 patients with other localized infections. Antigen was not detected in the urine of 40 healthy individuals, but the urine of 16 (8%) of 194 hospitalized patients with diagnoses other than melioidosis gave a positive results. Of the false-positive results, 13 of 16 were associated with bacteriuria ≥ 104 colony-forming units/ml. At a cutoff titer of 1:10, the sensitivity and specificity of the test were 81% and 96%, respectively. Enzyme immunoassay detection of urinary antigen is a valuable and rapid laboratory test for the early diagnosis of acute melioidosis.