NEW YORK (Reuters Health) - A new method employing electrochemical DNA biosensors rapidly and accurately identifies bacterial pathogens in urine, researchers in California report.
"We believe that we are taking medicine out of the era of Louis Pasteur, when identifying bacteria requires waiting for them to grow, into the era of molecular medicine," Dr. David A. Haake from the David Geffen School of Medicine at UCLA told Reuters Health. "In effect, we are translating nucleic acid sequences into electrical signals, much as Alexander Graham Bell translated sound into electrical signals."
Dr. Haake and colleagues evaluated the ability of a panel of oligonucleotide capture and detector probe pairs to detect and identify common uropathogens.
The "UTI chip" produced accurate results in pilot experiments with clinical urine specimens representing a broad range of uropathogen species and concentrations across a broad range of urine specimen parameters related to the host inflammatory response, the authors report in the February issue of the Journal of Clinical Microbiology.
This approach yielded an overall sensitivity for detection of uropathogens in clinical urine specimens of 93% (54 out of 58 pathogens in blinded clinical urine specimens), the results indicate, and an estimated specificity of 83%.
The sensitivity of the probe for detection of gram-negative bacteria in clinical urine specimens was 100% (48/48), the researchers note. When species-specific probes were used, only one specimen containing Klebsiella pneumoniae was a false-negative using the Klebsiella and Enterobacter probe.
"The culture- and PCR-independent molecular identification was achieved in 45 minutes," the investigators write. "The ability of the sensor to provide genotypic identification of uropathogens and to rapidly differentiate between bacterial pathogens is clearly superior to current clinical microbiology approaches, which are limited by the growth rates of bacteria and typically require at least 48 hours from sample collection to reporting."
"Identification of bacteria using an electrochemical sensor is a replacement technology for the standard clinical microbiology procedures, which currently cost around $200 per test," Dr. Haake explained. "The most expensive component of the current approach is the cost of a microbiology technologist's time to process the specimen. By contrast, the electrochemical sensor would be fully automated all the way from specimen input to data output."
"The sensor method we are using is very different from another molecular approach, PCR," Dr. Haake added. "The sensor has several key advantages over PCR, one of which is that no target amplification is required. Because PCR requires polymerase enzymes to amplify the target, and the polymerase enzymes are very sensitive to inhibitors in clinical specimens, the nucleic acids in the specimens have to be purified before the amplification step. Our paper...shows that the sensor works very well on crude bacterial lysates from clinical urine specimens."
No comments:
Post a Comment