Novel LAMP assay detects antibiotic susceptibility in UTIs

A novel test detected the antibiotic susceptibility of urinary tract infections in less than 30 minutes using digital real-time loop-mediated isothermal amplification, or dLAMP, according to findings recently published in Science Translational Medicine.

“UTIs are among the most common bacterial infections, accounting for [approximately] 8 million primary care visits annually, and are almost always treated with antibiotics,” Rustem F. Ismagilov, PhD, of the division of chemistry and chemical engineering at California Institute of Technology, and colleagues wrote.

Because no rapid antibiotic susceptibility test is currently available for UTIs, these infections are commonly treated with fluoroquinolones, leading to increased antibiotic resistance and limited treatment options, according to the researchers.

“Thus, UTIs are a specific clinical scenario where an inexpensive and rapid [antibiotic susceptibility test] would notably improve patient outcomes and antimicrobial stewardship,” Ismagilov and colleagues wrote.

The researchers diluted urine samples and incubated them for 15 minutes before performing dLAMP analysis, calculating the ratios of concentrations of Escherichia coli bacterial DNA between samples that had been treated with antibiotics and those that had not. Samples with ratios below a preset threshold were considered susceptible. Ismagilov and colleagues validated the platform with 51 different samples with confirmed urinary tract infections.

Researchers compared these results to a commercial digital polymerase chain reaction assay, which required 2 hours. The dLAMP test detected susceptibility comparably to the polymerase chain reaction assay, but required just 6.7 minutes, the researchers reported.

“This [rapid digital antibiotic susceptibility test], if fully developed and validated for additional microorganisms, antibiotics and sample types and transitioned to a Clinical Laboratory Improvement Amendments-waived [point-of-care] device approved by the regulatory bodies, would enable rapid clinical decision-making, improve management of infectious diseases and increase antimicrobial stewardship,” Ismagilov and colleagues wrote. – by Andy Polhamus

Disclosures: Ismagilov is one of several authors listed on a patent for rapid digital antibiotic susceptibility testing, and holds a financial interest and consulting position for SlipChip Corp.