i-STAT Technology May Improve Detection of Burkholderia pseudomallei

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The i-STAT assay detected capsule from blood samples for 32% of those with melioidosis whose blood cultures were negative in both cohorts.
The i-STAT assay detected capsule from blood samples for 32% of those with melioidosis whose blood cultures were negative in both cohorts.

The i-STAT technology may detect the capsule of the bacteria Burkholderia pseudomallei and the purified anticapsular polysaccharide antibody in a superior fashion compared with the lateral flow immunoassay currently in use, according to findings published in Clinical Infectious Diseases.

Melioidosis is a life-threatening disease caused by the gram-negative bacterium B pseudomallei, and although early and accurate diagnosis is critical, a lack of clear clinical signs and symptoms often results in misdiagnosis. The i-STAT is a portable blood analyzer that has multiple-analysis capabilities and is a hand-held, easy to use device that produces laboratory-quality results in minutes. A prototype melioidosis assay cartridge was developed for the i-STAT device using the anti-B pseudomallei purified anticapsular polysaccharide antibody. The assay was evaluated on 414 clinical specimens obtained from patients in Australia and Cambodia. 

 

Results showed that the i-STAT assay accurately differentiated blood cultures from Australian participants who were positive for melioidosis from samples of those who were hospitalized with other types of infections (area under the curve, 0.91; 95% CI, 0.817-1.0). An assay cutoff with 76% sensitivity and 94% specificity was developed and the i-STAT technology correctly classified 88% (n=74) of the Australian patients but only 46% (6/13) of those from Cambodia whose blood cultures were positive for melioidosis. However, the assay did detect the bacterial capsule from blood samples for 32% of those whose blood cultures were negative for melioidosis in both cohorts, including those in Cambodia who were previously undiagnosed with melioidosis. The assay also showed high sensitivity and specificity for urine, pus, and sputum. 

“We encourage pursuit of appropriately sensitive point of care platforms to realize the true diagnostic potential of this and other biomarker and receptor pairs for melioidosis and indeed for other bacterial pathogens that are causing severe sepsis in many parts of the world where health resources are limited,” the researchers concluded.

Reference

Schully KL, Young CC, Mayo M, et al. Next generation diagnostics for melioidosis: evaluation of a prototype i-STAT cartridge to detect burkholderia pseudomallei biomarkers [published online October 31, 2018]. Clin Infect Dis. doi: 10.1093/cid/ciy929

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