Tag Archives: C. diff. PCR technology

New Study Evaluated Rectal Swabs For Clostridium difficile Testing

Clostridium difficile (C. diff) is among one of the top 18-drug-resistant threats to the United States according to the Centers for Disease Control and Prevention, responsible for around 250,000 infections on an annual basis and 14,000 deaths.

When it comes to diagnosis, microbiological testing of stool samples is often used. However, a new study suggests that for simple PCR-based detection of C. diff, dry rectal swabs were an effective substitute for the use of stool samples.

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“With this study, we proved that rectal swabs for the diagnosis of C. diff infection by PCR can replace the actually used stool samples,” study author Nathalie Jazmati, MD, University Hospital of Cologne, told our sister publication MD Magazine. “That will be more convenient for both patients and health care workers. Nevertheless, this was only a small study and our results have to be confirmed in a bigger clinical trial.”

In an effort to examine methods other than the analysis of stool specimens for C. diff confirmation, a research team from Germany examined the way rectal swabs with liquid transport medium and nylon flocked dry swabs performed for the detection of C. diff; they also evaluated the impact of storage temperature on the swabs.

For their study, the researchers collected 60 clinical stool samples that tested positive for C. diff by PCR and used them to simulate rectal swabs. Then, researchers dipped both wet and dry swabs into the stool and tested by PCR 3 times.

The first test took place immediately after the simulation “swab,” then, after 1 month and 3 months storage at -80°C. When the researchers tested the frozen samples, they first thawed them at room temperature for 15 minutes and the liquid swabs were vortexed for 30 seconds.

Testing all of the dry swabs 100% successfully detected C. diff, an equal rate of the stool sample testing; this proved true for all 3 phases of testing, and the researchers learned that no significant differences were found on the samples after they were frozen and thawed.

The detection rate for the other 30 liquid swabs was lower, at 83.2% accuracy. However, the researchers determined the temperature and the freezing and thawing of these samples did not have any significant impact.

The authors added that their results fall in line with other studies that tested PCR from rectal swabs in the detection of C. diff. The idea of using rectal swabs instead of stool samples isn’t new—it dates back to 1987.

Liquid swabs are currently cleared by the US Food and Drug Administration (FDA) for transport and the culture of gastrointestinal pathogens, the study authors continued, but it is not FDA approved for use with any molecular gastrointestinal assays.

In the future, dry swabs would “be appropriate and can probably speed up and facilitate the diagnosis of C. diff infection,” the researchers wrote, but warned, “nevertheless, using single step PCR-based detection of C. diff may lead to overdiagnosis of C. diff infection due to the high sensitivity but lower specificity of PCR.”

That marks a heightened importance for the careful clinical evaluation of the patient: Are they an asymptomatic carrier? Is there another reason for the patient’s diarrhea? Do they truly have a C. diff infection? All important questions to continue to ask.

While liquid swabs cannot substitute for the two-step laboratory diagnosis of C. diff, the researchers believe that their study shows the dry swab is a suitable alternative to stool sample testing.

Roche Launches cobas Liat PCR System With Four Assays — C. diff., Strep A, Influenza A/B and Influenza A/B & RSV

Roche launches cobas Liat PCR System with four assays into CE-markets

  • First 20 minute real-time PCR nucleic acid test to detect Clostridium difficile, which supports time-sensitive diagnoses in hospitals, urgent care settings and physician offices
  • Infections with Clostridium difficile can quickly become life threatening to high-risk patients
  • cobas Liat PCR System also includes tests for strep A, influenza A/B and influenza A/B & RSV

Roche  – April 3, 2017 –  announced the CE-IVD launch of the cobas® Liat® PCR System with four assays including first 20 minute real-time PCR nucleic acid test to detect Clostridium difficile (C. diff). Countries accepting CE mark are the first to receive access to the cobas® Cdiff test, which detects C. diff in stool specimens from symptomatic patients1 and provides rapid and definitive results in under 20 minutes. Timely and accurate diagnosis of this infection is important because it can quickly become life threatening, especially to high-risk patients such as the elderly, immuno-compromised and those undergoing antibiotic treatment.

“Roche is proud to bring the advantages of real-time PCR testing to point-of-care settings with the cobas® Liat® System,” said Roland Diggelmann, CEO of Roche Diagnostics. “The system now includes Europe’s first real-time PCR test for patients suspected of C. diff infection with results in less than 20 minutes. As one of the major causes of healthcare associated infections (HAI), C. diff not only causes significant financial burden on healthcare systems but can also lead to severe complications for the patient if the disease is not caught in time.”

The cobas® Cdiff assay, an automated, in vitro diagnostic, real time PCR test, offers minimal handling steps, a simplified workflow, and access to urgent results. Traditional diagnostic methods may take several hours for results to be delivered to clinicians. The cobas® Cdiff assay’s speed and simplicity make it ideal for STAT and out-of-hours testing, providing results when and where they are needed most.
The benefits of accurate and timely diagnoses for patient care are not unique to HAIs. The cobas® Liat® System brings real-time answers for patients and their caregivers with the assurances of PCR technology in 20 minutes or less for all assays in the portfolio. The expanded menu of assays for use on the cobas® Liat® System includes the respiratory portfolio of cobas® Strep A, cobas® Influenza A/B, cobas® Influenza A/B & RSV. The latest assay, cobas® Cdiff, is the first in the HAI portfolio and will be joined during the second quarter of 2017 by cobas® MRSA/SA for CE marked countries.


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About the cobas Liat System

Utilizing PCR technology, the innovative cobas® Liat® System fully automates the testing process, simplifies workflow and enables healthcare professionals to perform molecular testing in a variety of settings with speed, reliability and minimal training. Definitive results are generated in 20 minutes or less to aid in treatment decisions. The current portfolio of assays include cobas® Cdiff, cobas® Strep A, cobas® Influenza A/B and cobas® Influenza A/B & RSV. Assays for other infectious diseases are in development.

For more information please visit www.cobasliat.com.

The cobas® Liat® System is not commercially available in all markets.

About Roche

Roche is a global pioneer in pharmaceuticals and diagnostics focused on advancing science to improve people’s lives. The combined strengths of pharmaceuticals and diagnostics under one roof have made Roche the leader in personalised healthcare – a strategy that aims to fit the right treatment to each patient in the best way possible.

Roche is the world’s largest biotech company, with truly differentiated medicines in oncology, immunology, infectious diseases, ophthalmology and diseases of the central nervous system. Roche is also the world leader in in vitro diagnostics and tissue-based cancer diagnostics, and a frontrunner in diabetes management.
Founded in 1896, Roche continues to search for better ways to prevent, diagnose and treat diseases and make a sustainable contribution to society. The company also aims for improving patient access to medical innovations by working with all relevant stakeholders. Twenty-nine medicines developed by Roche are included in the World Health Organization Model Lists of Essential Medicines, among them life-saving antibiotics, antimalarials and cancer medicines. Roche has been recognized as the Group Leader in sustainability within the Pharmaceuticals, Biotechnology & Life Sciences Industry eight years in a row by the Dow Jones Sustainability Indices (DJSI).

The Roche Group, headquartered in Basel, Switzerland, is active in over 100 countries and in 2016 employed more than 94,000 people worldwide. In 2016, Roche invested CHF 9.9 billion in R&D and posted sales of CHF 50.6 billion. Genentech, in the United States, is a wholly owned member of the Roche Group. Roche is the majority shareholder in Chugai Pharmaceutical, Japan. For more information, please visit http://www.roche.com


“The C Diff Foundation’s mission is to educate and advocate for Clostridium difficile infection prevention, treatments, support, and environmental safety worldwide.
The C Diff Foundation’s organization is comprised of 100% volunteering members who are dedicated to our mission and adhere to the Foundation’s Code of Ethics
which prohibits the endorsement and promotion of products, services, medications, or clinical studies in progress. 
All website entries, public presentations, and workshops are to raise C. diff. infection awareness in all areas of the C Diff Foundation’s mission statement, including infection prevention, sepsis, healthcare-associated infections, antimicrobial resistance, antibiotic stewardship and provide education on all the above.”