Factsheet: Viable but non-culturable bacteria


what are vbnc bacteria?

What are VBNC bacteria?

The viable but non-culturable (VBNC) state is a unique strategy with which bacteria respond to unfavorable environmental conditions. In the VBNC state bacteria have a low metabolic activity and often do not grow or divide. Nevertheless, they are viable and in some cases, they can still be infectious.

Why are VBNC bacteria a problem?

As some of the VBNC bacteria can still be infectious and cause disease, they are considered a threat to humans and animals. Importantly, the standard method for detection of many bacteria in food and drinks, is based on cultivating bacteria in culture media. Because VBNC bacteria usually do not show growth on agar plates or in liquid culture media, they are not detected by the standard method.

Examples of pathogens that can enter the VBNC state

• Legionella pneumophila
• Listeria monocytogenes
• Pseudomonas aeruginosa
• Salmonella typhi
• Salmonella typhimurium
• Streptococcus faecalis

How can VBNC bacteria be detected?

The combination of immunomagnetic separation of target cells and detection by flow cytometry via fluorescent antibodies is fast and reliable.
rqmicro successfully adapts this technology, and is thereby able to provide solid results for VBNC while keeping the cell integrity intact.

Check out this page to find out more about rqmicro’s solution on VBNC detection.


Viable but Nonculturable Bacteria: Food Safety and Public Health Perspective

Increase of Legionellosis cases in Europe – Infographics July 2017


The number of cases of the potentially fatal Legionnaires’ disease seems to be rising in Europe according to the July 2017 Legionnaires’ disease surveillance and outbreak report. It concludes that there is a lack of rapid and reliable control measures for water systems to prevent outbreaks.

Infographics - Legionnaires' disease in Europe rqmicro July 2017

Preventing outbreaks with efficient monitoring

One highly efficient means of preventing Legionellosis outbreaks is the regular and close monitoring of water systems, which is of particular importance for facilities like hospitals with transplant programs or elderly homes (Tablan O.C., 2003). The accredited standard method for Legionella detection, ISO 1173, is based on cultivating Legionella on plates, which can lead to variable results and takes up to 14 days. One reason for this is that a non-negligible portion of Legionella present in a sample do not grow on agar and is thus not detected by the standard method – the viable but non-culturable fraction of cells. Additionally, competing flora often overgrows agar plates and thereby prevents growth of Legionella. Therefore, the accuracy and reliability of the data acquired with the standard method is neither satisfactory nor sufficient for the evaluation of water systems.

The rqmicro method provides highly precise and fast solutions:

  • Separation, concentration and purification of target cells from any matrix in 1 -2 hours instead of 14 days – Rapid testing method provides immediate process feedback
  • Getting rid of 95% of the competing flora – Delivery of ready-to-use samples for cultivation on agar plates, flow cytometry, PCR, microscopy, etc.
  • Detection of viable but non-culturable bacteria – Minimizing the risk of not only Legionnaires’ disease but also Pontiac fever
  • Automatization & easy implementation – Limited training required

rqmicro’s vision is that consumers worldwide benefit from water and food which is free from microbiological contamination. A crucial step towards realizing that vision is to detect pathogens in a quick and accurate way. Our CellStream instrument and the test kit for Legionella pneumophila SG 1 represent an important step towards the realization of this vision.




Beauté, J. o. (2017, July). LEGIONNAIRES’ DISEASE IN EUROPE, 2011 TO 2015. Retrieved from Eurosurveillance: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=22829

Tablan O.C., Anderson L.J., Besser R.  (2003). Guidlines For Preventing Health-Care–Associated Pneumonia. Retrieved from Legionella.org: http://legionella.org/guidelines-for-preventing-health-care-associated-pneumonia-2003/

United States Department of Labor. (2016). Legionnaires’ Disease eTool: Disease Recognition. Retrieved from United States Department of Labor – OSHA: https://www.osha.gov/dts/osta/otm/legionnaires/disease_rec.html

World Health Organization. (2016, June). Legionellosis. Retrieved from World Health Organization: http://www.who.int/mediacentre/factsheets/fs285/en/


Award at the Swiss Diagnostics Start Up Day 2017

Swissbiolabs organized a start-up challenge on 29th of June to award and support promising innovative ideas in diagnostics. We were very happy to participate at this great event and to get recognition in diagnostics with the second-place certificate.

rqmicro second place on swiss diagnostics start-up

CellStream & Legionella pneumophila SG1 Test Kit Video

In this video, Anna from the lab team will show you how easy it is to separate and quantify Legionella from tap water samples using our CellStream and Legionella pneumophila SG1 test kit.

rqmicro – CellStream & Legionella pneumophila SG1 Test Kit Application

New article about rqmicro’s technology by Laborpraxis.de

Take a look at this interesting article about rqmicro’s groundbreaking technology and its essential role in the field of Legionella detection (in German).

Quantify Legionella at record speed 

rqmicro featured in Laborpraxis.de

Check out this short article of our Lab-on-a-Chip Technology by laborpraxis.de (German)

Link: Legionellen aus Wasserproben isolieren

Download PDF: rqmicro Laborpraxis.de

Investor Summit 2017

rqmicro presented at the investor summit 2017 organized by the Swiss Economic Forum (SEF). View our trailer here: rqmicro AG – Trailer for Investor Summit 2017

Thank you all for the great interest in new water and food safety solutions and many good conversations!

Happy Holiday (Newsletter December 2016)

Happy holiday from rqmicro

We look back on an exciting and successful 2016 and are looking forward to interesting new challenges in 2017.

The CellStream device, successfully launched in the spring, allows rapid detection of Legionella within 1 to 2 hours. Laboratories in Switzerland and abroad rely on the rqmicro Legionella kit in combination with the CellStream.
New regulations, such as the monitoring of cooling systems, require innovative solutions. rqmicro provides the answer in the form of intelligent lab-on-a-chip technology, which detects pathogens in water samples quantitatively and with high specificity.



Request Product Demo


The rqmicro team continued to grow in 2016. With lots of physical effort and creativity, we have created ice sculptures at our Christmas party, which are connected to our mission in the field of microbiological safety of water and food.

We would like to sincerely thank you for your trust and we are looking forward to a lively exchange, productive cooperation and to meeting you personally at trade fairs or in your laboratory.



rqmicro among the Top 50 Startups in Switzerland

rqmicro has been featured again in the annual Top 100 List, this year on place 37! (up from place 74 in 2015)

Read here for more info on the Top 100 and the great event in Schlieren.


Startup Top 100


rqmicro at Lab-Supply Trade Fair in Ludwigshafen

rqmicro presented the CellStream instrument and kits on 7 September at the Lab-Supply Trade Fair in Ludwigshafen, Germany. Our next stop is Amsterdam for the ESGLI 2016 on 22-23 September!

rqmicro Lab Supply Kurpfalz Ludwigshafen

rqmicro stand at the Lab Supply trade fair in Ludwigshafen

Copyright 2013-2017 by rqmicro