Evaluation of the Lodestar DX: a comparison with traditional culture for the detection of bacteriuria in the workup of urinary tract infection

Abstract

Background: The Lodestar DX is a point-of-care test (POCT) using loop-mediated isothermal amplification (LAMP) to detect common uropathogens. Novel POCTs may provide an adjunct in the diagnostic work up of urinary tract infection (UTI).

Objectives: To evaluate the performance of the Lodestar DX in the identification of bacteriuria.

Methods: We compared the Lodestar DX against urine culture results from August to November 2024 at the Eastern Pathology Alliance in non-pregnant adults.

Results: 379 urine samples were tested on the Lodestar DX. 344 (90%) of these passed both internal controls. Summary Lodestar DX performance was sensitivity 85.6% (95% CI 69.2%-94.6%), specificity 92.0% (95% CI 88.1%-94.9%), positive predictive value 64.1% (95% CI 48.7%-77.2%), negative predictive value 97.0% (95% CI 94.0%-98.6%) and overall accuracy 91.2% (95% CI 87.5%-94.0%).In cultures positive for their respective organisms, the sensitivity was 87.9% (n = 66, 95% CI 77.5%-94.6%) for Escherichia coli, 80% (n = 20, 95% CI 56.3%-94.3%) for Enterococcus, 27.3% (n = 11, 95% CI 6.0%-61%) for Staphylococcus aureus, 92.3% (n = 13, 95% CI 64.0%-99.8%) for Staphylococcus saprophyticus, 93.8% (n = 16, 95% CI 69.8%-99.8%) for Proteus mirabilis, 84.2% (n = 19, 95% CI 60.4%-96.6%) for Pseudomonas aeruginosa and 100% sensitivity (n = 2, 95% CI 15.8%-100%) for Klebsiella pneumoniae.

Conclusions: In summary, the Lodestar DX had good performance for the detection of uropathogens apart from S. aureus. Further comparison with other POCTs would be beneficial.

Figure 1.

Flowchart of urine processing and Lodestar DX testing.

Figure 2.

Process for review of inoculum plates and assignment of interpretation.

Figure 3.

Urine WBC count plotted against Lodestar DX control result.

Figure 4.

Issued laboratory reports for urine samples passing Lodestar DX controls.