Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New diagnostic test can detect chlamydia trachomatis in less than 20 minutes

12.12.2013
Assay offers potential for high sensitivity testing at point-of-care settings, say researchers in The Journal of Molecular Diagnostics

Researchers have developed a new assay for rapid and sensitive detection of Chlamydia trachomatis, the most common sexually transmitted infection (STI) in humans. This procedure takes less than 20 minutes and can be easily performed at the point of care (POC) during the patient's visit, reports The Journal of Molecular Diagnostics.

C. trachomatis affects 5% to 10% of the population and is particularly common in young adults under 25 years. It is a major public health concern due to its prevalence and potential severe long-term consequences. One of the main reasons it is so prevalent is that in the majority of cases (75% of women and 50% of men) there are minimal to no symptoms, and it therefore often goes undiagnosed.

Infection is associated with non-gonococcal urethritis in men and several inflammatory reproductive tract syndromes in women such as inflammation of the uterine cervix and pelvic inflammatory disease. Untreated, the infection increases the risk of ectopic pregnancy and is one of the leading causes of female infertility worldwide.

The assay uses recombinase polymerase amplification (RPA), a nucleic acid amplification technique (NAAT), to detect C. trachomatis directly from urine samples. Because the assay's novel approach does not require the purification of total DNA from the urine sample, the need for specialized equipment is eliminated. The procedure is significantly less laborious, less time-consuming, and consequently less expensive. It is relatively simple to perform and could therefore be applied in numerous POC settings.

"The assay enables highly specific C. trachomatis detection with sensitivity levels significantly improved compared to currently available C. trachomatis POC assays," says Ülo Langel, PhD, Professor of Molecular Biotechnology, University of Tartu, Estonia, and Professor of Neurochemistry, Stockholm University, Sweden.

Existing polymerase chain reaction (PCR)-based techniques for testing C. trachomatis are widely applied but are only suitable for use in hospitals with trained staff and expensive machinery. Studies have shown that up to 50% of patients never return to get the diagnostic result or required treatment.

Although several rapid-diagnosis POC tests have already been developed, none offer a comparable sensitivity to hospital-based techniques. Recent independent studies have shown that currently available POC tests have a sensitivity of just 10% to 40%. Initial analysis of the new assay's performance indicated a specificity of 100% and a sensitivity of 83%, evidence of its potential reliability.

"The alarmingly poor performance of the available POC tests for C. trachomatis has limited their wider use, and there is a clear requirement for more sensitive and cost-effective diagnostic platforms. Hence, the need for an applicable on-site test that offers reasonably sensitive detection," concludes Prof. Langel.

TECHNICAL DETAILS OF THE STUDY

Recombinase polymerase amplification (RPA) is a nucleic acid amplification technique (NAAT) – a laboratory technique that involves the in vitro synthesis of many copies of DNA or RNA from one original template. These techniques have revolutionized diagnostic technology. Current technologies that allow the detection of amplification in real time are fast becoming diagnostic industry standards.

C. trachomatis cells contain plasmids (small DNA molecules that are separate from chromosomal DNA) that have a number of coding sequences. For identification and amplification by RPA, researchers selected a gene fragment within a gene (CDS2) that was conserved across sexually transmitted C. trachomatis strains. The assay does not require the purification of total DNA from the urine sample. Heating the sample for five minutes at 90°C is enough to release a sufficient amount of the amplification target to determine whether the pathogen is present. Urine contains polymerase chain reaction (PCR) inhibitors, but up to 5 μl of urine can be added without affecting sensitivity of the RPA, whereas the addition of 10 μl affects amplification efficiency significantly.

The C. trachomatis assay developed here was able to detect at least 50 copies of the CDS2 target. C. trachomatis harbors, on average, between four and ten copies of the plasmid per elementary body depending on the strain and development stage. The lowest detectable amount of the C. trachomatis RPA assay can therefore be translated to 5 to 12 pathogens per reaction and is in the same range as other nucleic acid amplification-based techniques.

The assay was tested on urine samples from 70 patients (51 females and 19 males) attending a sexual health clinic in Estonia. The samples were tested in parallel using RPA and Roche Cobas Amplicor C. trachomatis assays.

Fifty-eight samples tested negative in both assays. As no false negatives were detected, the clinical specificity of the C. trachomatis RPA assay can be estimated at 100%.

Twelve of the samples tested as positive using the Roche assay. Of these, 10 tested positive and two tested negative in the RPA reaction. Based on these results, the clinical sensitivity of the RPA assay can be estimated at 83%.

Of the 12 patients who tested positive, three complained of symptoms. The other nine patients were asymptomatic. Of the 58 C. trachomatis-negative patients, 15 (26%) complained of symptoms that could be associated with C. trachomatis infection. One of these tested positive for N. gonorrhoeae and M. genitalium. Others were diagnosed with bladder inflammation (two patients), bacterial vaginosis (five patients), yeast infection (four patients), or abdominal pain of non-gynecological origins (three patients).

Eileen Leahy | EurekAlert!
Further information:
http://www.elsevier.com

More articles from Health and Medicine:

nachricht Satellites, airport visibility readings shed light on troops' exposure to air pollution
09.12.2016 | Veterans Affairs Research Communications

nachricht Oxygen can wake up dormant bacteria for antibiotic attacks
08.12.2016 | Penn State

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>