Rapid test for Listeria Risk in food factories

NEMIS technologies Listeria Risk test

The risk of Listeria is ever-present in food production environments. That’s why testing for Listeria spp. is a crucial component of your environmental monitoring program. Listeria is a leading cause of foodborne illness and costly product recalls. Protect your customers and your business with the N-Light™ Listeria spp. Test from NEMIS Technologies. Our simple and effective testing platform allows you to assess your factory’s true contamination risk and prevent outbreaks before they start. Best of all, our tests don’t require complicated training to be properly used. They’re the simple and cost-effective solution for efficient environmental monitoring.

The NEMIS N-Light™ Listeria spp. Test utilises our proprietary Aquaspark™ platform which incorporates pioneering phage technology to quickly detect even small amounts of live bacteria. The N-Light™ Listeria spp. Test detects a broad spectrum of Listeria species, including Listeria monocytogenes. This allows you to quickly assess and improve hygiene practices in your food production environment. Unlike traditional lab tests that take days to get results, the NEMIS N-Light™ Listeria spp. Test produces actionable results in as little as 24 hours. Fast, accurate, easy to use. Take control of environmental monitoring with solutions from NEMIS Technologies.

Listeria spp. — status quo

Listeria is a genus of bacteria that often enters food production facilities through raw materials, posing a potential risk of contamination. While not all Listeria species are pathogenic, the presence of species such as Listeria monocytogenes in food products can lead to severe foodborne illnesses, particularly in high-risk groups.

AYOPI Groups
are at the highest risk

CDC estimates that Listeriosis is the third leading cause of death from foodborne illness, with about 260 deaths per year.

Pregnant women and newborns

Adults aged 65 and older

People with weakened immune systems

N-Light™ Listeria spp.
Indicator test

Detecting Listeria spp. is currently a crucial component of environmental monitoring programs in the food industry. The N-Light™ Listeria spp. indicator test provides a potent and broad-spectrum solution for detecting a wide range of Listeria species, enhancing factory hygiene and safety practices.

Compared to tests focused solely on Listeria monocytogenes, N-Light™ Listeria spp. means more positive results and more actionable insights for improving hygiene standards in food production environments.

1 Identification of sampling sites and zones with N-Light™ Listeria spp.
2 Positive result
3 Listeria monocytogenes
Listeria innocua
Listeria welshimeri
Listeria grayi
Listeria marthii

N-Light™ Listeria spp. tube contains a unique, innovative technology

The biosafety cap for safe
on-site enrichment

Pioneering phage
technology

Patented AquaSpark™
platform for detection of live bacteria

See our technology
in action

Consider your sampling needs:
N-Light™ MaxiSampler vs N-Light™ swab

Patent pending

By choosing the right tool for each surface type and size, you can meet regulatory guidelines effectively while maximizing sampling efficiency and accuracy.

N-Light™ MaxiSampler

Patent pending

Designed for Large Surface Coverage Excels in sampling larger, flat surfaces such as floors, walls, and countertops. Provides broader detection of potential contamination across sizable zones.
Guideline Endorsed for Broader Surveillance Environmental monitoring guidelines often endorse sponges for larger, straightforward areas to capture a comprehensive view of contamination risks.
Surface Area With a typical range up to 0.3 m² (like a 30×30 cm area), N-Light™ MaxiSampler maximizes sampling on expansive surfaces, offering robust environmental surveillance.

N-Light™ swab

Ideal for Hard-to-Reach Areas Swabs are perfect for narrow or intricate surfaces such as equipment joints, cracks, and small parts that might otherwise be missed.
Recommended by Guidelines for Small Surface Sampling Many guidelines, such as those from the FDA and ISO, suggest swabs for sampling limited areas or surfaces with complex geometries.
Surface Area Typically covers around 0.1m² (like a 10×10 cm area), making swabs ideal for focused or spot sampling on high-touch or high-risk zones.

Learn more

Simple, effective, testing process

1. Sample

2. Transfer

3. Incubate

24 h / 37 °C

4. Activate

5 min

5. Measure

10 s

Lab confirmation:

Positive N-Light™ Listeria spp. test tubes can be sent to an internal or external microbiological laboratory for analysis of the presence of Listeria spp. and Listeria monocytogenes with cultural methods (e.g. ISO 11290-1) or PCR methods (e.g. Eurofins).

Recommended products:

N-Light™ L.monocytogenes Learn more

N-Light™ Salmonella Risk Learn more

N-Light™ E.coli Learn more

N-Light™ ATP Learn more

N-Light™ MaxiSampler: Revolutionising Surface Sampling Learn more

N-Light™ Listeria spp.

NEMIS product REF 00048

Product description

N-Light™ Listeria spp. is a qualitative test method for rapid detection of the Listeria spp. bacteria, including Listeria innocua, Listeria welshimeri and the pathogenic species Listeria monocytogenes. The test method is suitable for use in food processing areas and equipment as part of an environmental monitoring program. Final test results are available 24 h after sampling.

Storage conditions: 2-8 °C / 36-46 °F, DO NOT FREEZE

Transport conditions: ambient (short duration only)

HS tariff number: 38221900

Country of origin: CH

Each test consists of the following components:

N-Light™ Biosafety Tube, filled with N-Light™ Listeria spp. Enrichment Broth, 2 ml
N-Light™ Dispensing Closure, containing the N-Light™ Listeria spp. AquaSpark® tablet, 1 pc. / 15 mg

Technical specifications

NEMIS tests each production batch against the specifications listed below.

General characteristics	Specification
Broth general appearance	Yellowish, clear waterlike solution
Broth visible turbidity	No particles
Broth optical density (OD600)	< 0.10
Broth Volume	1.80 – 2.20 ml
Broth pH value	6.60 – 7.00
Functionality test (Background)	< 3000 RLU (NEMIS BTL1 luminometer)
Quantity of AquaSpark®	Internal specification

Microbial performance	Specification
Sterility control	No growth, 7 days @ 37 °C
L. monocytogenes ATCC 19111	Positive result
L. welshimeri ATCC 35 897	Positive result
L. innocua WSCL 2011	Positive result
E. coli ATCC 8739	Negative result
E. faecalis ATCC 29212	Negative result
S. aureus DSM 1104	Negative result

Certificates of analysis are available on request.

Packaging specifications

General characteristics	Primary packaging (test tube)	Secondary packaging (product box)	Tertiary packaging (distributor box)
Amount	1 test	50 tests (1 x 50)	300 tests (6 x 50)
Bar code / GTIN	See below	7649994979430	7649994979423
Length	1.9 cm	26.2 cm	36.3 cm
Width	1.9 cm	11.5 cm	27.4 cm
Height	11.1 cm	11.6 cm	24.4 cm
Net weight	0.010 kg	0.600 kg	3.950 kg
Total plastic amount	0.008 kg	0.376 kg	2.256 kg
Non-reusable plastic amount  — in the product  — in the packaging	0.008 kg 0.000 kg	0.375 kg 0.001 kg	2.250 kg 0.006 Kg

Lot and serial number of the test

Each test has a unique number printed on the tube label. The human readable format is LLLLLLL-XXXXX. Additionally, this number is encoded without the hyphen in a linear barcode of type Code 128:

LLLLLLL: 7-digit lot number
XXXXX: 5-digit consecutive number

N-Light™ Listeria spp.
Required materials

N-Light™ Listeria spp. test tubes
NEMIS Bench-top Luminometer
NEMIS Dry Block Heater
Kitchen Timer
Optional: N-Light™ Activation Tool (REF 00008)
N-Light™ sampling devices containing compatible moistening solution
- N-Light™ sterile dry swabs BP with separate PBS buffer (REF 00039)
- N-Light™ sterile dry swabs BP with separate neutralizer (REF 00037)
- N-Light™ sterile MaxiSamplers with separate PBS buffer (REF 00060)
- N-Light™ sterile MaxiSamplers with separate neutralizer (REF 00064)

N-Light™ Listeria spp. Brochure N-Light™ Listeria spp. Instructions for Use

Training

At NEMIS, your success is our priority. Our experts are here to guide you with comprehensive training resources, including instructional videos, to help your team confidently and accurately perform procedures. For on-demand training requests, please contact us at techsupport@nemistech.com.

FAQ

The N-Light™ Listeria spp. test is a qualitative test for rapidly detecting the Listeria spp. group of bacteria which indicate the potential presence of the foodborne bacterial pathogen Listeria monocytogenes. It is intended for use in food processing areas and on food manufacturing equipment as part of an environmental monitoring program.

The only required instruments are the NEMIS dry block heater and the NEMIS Luminometer. They can be used on-site without any laboratory infrastructure. It is recommended to perform the test in a separate room, distant from the production environment.

The N-Light™ Listeria spp. test will undergo the certification process for AOAC® Performance Tested Methods until end of 2025. Please contact sales@nemistech.com or techsupport@nemistech.com for a summary of internal validation data generated by NEMIS.

AquaSpark™ substrates are dioxetane compounds bearing molecular structures that are specifically recognized by target enzymes. When cleaved by an enzyme, AquaSpark™ substrates emit light by a process called chemiluminescence. The N-Light™ Listeria spp. test uses an AquaSpark™ substrate with high specificity for Listeria sensu strict species.

The N-Light™ Listeria spp. broth contains a mixture of nutrients for bacterial growth combined with selective agents limiting the growth of non-target bacteria. These are antibiotics, salts and a proprietary mix of bacteriophages for suppression of closely related bacteria.

RLU stands for Relative Light Units and is the unit of measure used in the NEMIS luminometer. RLU values are proportional to the amount of AquaSpark™ light emission induced by a specific enzyme. For each NEMIS test, a certain RLU threshold for presumptive positive tests has been validated in extensive experimental studies at NEMIS. Below the threshold, the test result is considered negative. In the case of the N-Light™ Listeria spp., a sample is considered presumptive positive when the signal is above 4'000 RLU.

Results can be obtained after 24 hours of incubation at 37°C. A reduction of the incubation time by one hour (23 h) is also ok, but incubation times shorter than that will decrease the sensitivity of the N-Light™ Listeria spp. test. Likewise, up to six hours longer incubation time (30 h) will not affect the test, but longer incubation times have not yet been validated and may lead to unreliable results. Developed N-Light™ Listeria spp. test tubes, safely closed with the biosafety cap, can be sent to a biosafety level 2 lab for follow-up analysis. NEMIS offers a tube cutter for opening of the biosafety cap. Presence of Listeria spp. and/or Listeria monocytogenes in the broth can be analyzed by molecular methods (PCR, real-time PCR, immunoassays) or by cultural methods such as ISO 11290-1.

The test detects Listeria innocua, Listeria welshimeri, Listeria ivanovii and all serotypes of Listeria monocytogenes. In field trials, NEMIS isolated mainly L. innocua and L. monocytogenes strains (confirmed by molecular methods). These species are known to be the most frequently occurring Listeria spp. strains in food factories.

In field trials conducted in food factories, the positivity rate of the N-Light™ Listeria spp. test was 21% to 39%, when sampling was done during production and the selection of sampling sites was focused on locations with a high likelihood of Listeria spp. being present. NEMIS considers the observed positivity rate as being in a useful range for guiding corrective actions and verifying proper cleaning.

The N-Light™ Listeria spp. test is based on the detection of an enzyme which may also occur in some other bacteria which can grow in the NEMIS broth. Therefore, there is a certain likelihood of false positive test results. In field trials conducted in food factories, 30 to 60% of the positive N-Light™ Listeria spp. tests could be confirmed in follow-up analyses by cultural and molecular methods as Listeria spp. Other species found in positive tests were Vagococcus fluvialis, Bacillus saprophyticus, Niallia circulans, Mammalicoccus sciuri and Enterococcus thailandicus. The fraction of false positives obtained with the N-Light™ Listeria spp. test is lower than that of other rapid on-site tests which mostly detect beta-glucosidase activity, an enzyme frequently occurring in a broad range Gram positive bacteria. For a screening assay intended for fast and easy monitoring of the Listeria risk in a factory, the accuracy is considered as good.

The test is capable of detecting Listeria spp. starting from single-digit numbers of bacteria on sampled surfaces. Good swabbing practice and accurate compliance with the test IFU are required for achieving highest sensitivity.

As the detection mechanism relies on active enzymes which are only produced by viable bacterial cells, dead Listeria are not detected.

It is possible to collect samples from production lines or sites that have not been recently cleaned. Sample location and application of N-Light™ Listeria spp. should be categorized as follows:

Food or dirt residue exposed surfaces within the production or before cleaning
Samples taken from production lines (both during and after production) and other places in the facility that are regularly cleaned are well within the capacity of our test. Make sure not to overload the sample with food residues. Rather go into niches and cavities of machines and apply pressure on surfaces. Sampling more “dirt” is not necessarily useful as persistent Listeria on equipment or infrastructure should be detected.
Direct sampling of food or in places of high dirt / food residue concentration
Meticulous sampling is required to ensure no test tube overload. Do not directly collect food residues. Examples of high load sampling spots are uncleaned drains, smeared water tanks, or the inside of uncleaned food residue collection containers.

Hot spots that accurately indicate potential product contamination should be preferentially sampled. Please refer to your Hazard Analysis and Critical Control Points (HACCP) plan.

Optimally, high-risk spots should be swabbed on a daily basis after each cleaning or production shift. In case of a positive result, immediate corrective action should be taken with re-cleaning and re-testing until a passing result can be measured. Lower-risk control points may be tested less frequently.