Urine-based amplified DNA probe test for STDs
October 1, 2000; p. 631 A-632 A
Copyright 2000 American Chemical Society
_Analytical Chemistry_ Magazine, News and Features Section
MEETING NEWS
News from the 52nd Annual Meeting of the American Association for Clinical Chemistry
Sandra Katzman reports from San Francisco, CA.
Screening for STDs
The first FDA-approved system for simultaneous amplification and detection of sexually transmitted diseases (STDs) is currently being used in limited situations, California county health officials told the annual meeting of clinical chemists in July. The system, called the BDProbeTec ET, is commercially available from Becton, Dickinson and Company, and it incorporates a urine-based amplified DNA probe assay. Because it is noninvasive, it eliminates the pain, expense, and lengthy analysis time characteristic of traditional probes, which have been used since the 1980s. In addition, it uses amplified molecular technology, which is 20-50% more sensitive than nonamplified methods.
The BDProbeTec ET uses a closed reagent system and a proprietary amplification technology, Strand Displacement Amplification (SDA)--a technique that uses a restriction enzyme and a polymerase. One advantage of SDA is that it allows real-time amplification and detection without thermocycling.
Jeffrey D. Klausner of the San Francisco Department of Public Health commended the use of the test in nightclubs, and Dennis V. Ferrero of San Joaquin County Public Health Services described an 18-month success story, in which the probe was used to screen youths for STDs. "Screening prevents costly health implications with its high-sensitivity, noninvasive amplified DNA tests. The solely urine-based test is 20 to 40 times faster than traditional nonamplified systems," Klausner says. Also, the technology has led to better acceptance of testing from the overwhelmingly nonsymptomatic affected population. Last year is the first time there has been a documented decrease in Chlamydia trachomatis among young women in his jurisdiction, Klausner adds.
The test has "revolutionized the approach to treatment of STDs," Klausner says. It gets around the "justifiable suspicion of STD testing," which results from the painful scraping for cell samples. The new test takes less time than the method for obtaining the analyte, a fact that produced some misleading but eye-catching advertising copy. "Your boyfriend takes 43 seconds. The test is even quicker," was interpreted scurrilously rather than scatologically.
"The technology has been improved to a point where testing is easy to provide in most laboratories," Ferrero tells Analytical Chemistry. "San Joaquin County is considering the possibility of do-it-yourself tests." Concerned with reaching youth, Ferrero is grateful to have urine testing administered in Teen Friendly Mobile Clinics with teen peer counselors. "164 children identified with STDs would not have been detected with traditional methods," Ferrero says. "This testing technology is standard for throughput." Similar screening programs are in effect in Los Angeles, Seattle, Denver, and Baltimore. Over 200 laboratories worldwide use the BDProbeTecET system, which is capable of performing tests not yet available in the United States, for organisms such _Mycobacterium tuberculosis, Mycobacterium avium, and Mycobacterium kansasii_.
"The nucleic acid amplification tests for GC [gonococcus or _Neisseria gonorrhoeae_, which causes gonorrhea] and chlamydia are the most sensitive and state-of-the-art tests available in the world. This technology will allow public health to make a significant dent in worldwide STDs," Ferrero tells Analytical Chemistry. The cost is $10-15 per test and $0.9-9 for one-dose or multiple-dose antibiotic treatments. "Our department has been evaluating chlamydia and GC tests for about 18 years," says Ferrero. "BDProbeTec is the latest U.S. FDA-approved test for this purpose." Klausner and Ferrero anticipate that, like measles and smallpox, chlamydia and gonorrhea may virtually disappear as a result of the new probe.
Illustration: Gonococci invading primary human urethral epithelial cells.
--Sandra Katzman