Abstract / Summary
GeneCapture is developing a novel, point-of-care, rapid AST technique that, when fully automated, can accomplish AST within 2 hours directly from a raw sample, representing a significant advancement in diagnostic capabilities. For this study, a panel of uropathogen isolates was collected from clinical specimens positive for urinary tract infection from various laboratories in the southern US. A selection of these isolates were then spiked into fresh clean-catch urine samples to produce mock samples covering a variety of antibiotic responses. Testing was performed on 20 strains of Escherichia coli , the cause of over 80% of UTIs, and 6 strains each of Klebsiella pneumoniae and Proteus mirabilis , the next most common causes. Each strain was tested against the susceptible, intermediate and resistant (S-I-R) breakpoints of up to 5 appropriate antibiotics including Amoxicillin-Clavulanate, Cefpodoxime, Ciprofloxacin, Nitrofurantoin and Trimethoprim-Sulfamethoxazole. The new method uses a phenotypic assessment of bacterial growth, comparing responses from bacteria treated with antibiotics at S-I-R breakpoint concentrations to untreated controls as the metric for determining susceptibility. Exposure to the drugs for only 90 minutes gave a Categorical Agreement of 98% to gold standard culture results across the resulting 247 bacteria/antibiotic pairs. Testing on separate days of nine of these strains in triplicate gave a reproducibility of 97%. The sequential steps of this novel AST - sample processing, growth, labeling, and counting - can readily be performed on an automated cartridge that is currently under development. The presented work, which took place in a laboratory setting, demonstrates the efficacy of the assay.
Importance: The rapid identification of pathogenic bacteria and determination of their antibiotic susceptibility directly from a patient sample remains a critical challenge in modern healthcare. Urinary tract infections (UTIs) account for a large proportion of global antibiotic use, and are increasingly resistant to former first-line treatments. Uncomplicated UTI (uUTI) is still generally treated empirically at the point of care, which leads to frequent follow-up visits. GeneCapture’s novel AST method relies on a phenotypic assessment of bacterial growth, as genotypic methods are not well suited for all bacteria. The speed of the assay is gained through using fresh samples, a novel rapid fluorescent in-situ hybridization technique, and accurate growth determination. The ease of use and affordability of the automated system should allow adoption at both clinical and point of care locations to allow more accurate and rapid antibiotic treatment.