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Rapid Pathogen Testing

 

Rapid Listeria Confirmations

 

To be at the cutting edge of scientific expertise and to offer our customers the best available technologies, ALcontrol Laboratories has introduced to the Food and Waters microbiology market a revolutionary new technique.

Firmly established in the clinical field, Matrix Assisted Laser Desorption/Ionization-Time Of Flight mass spectrometry (MALDI-TOF) has been in routine use in diagnostic laboratories for over 15 years. ALcontrol has now successfully gained accreditation for its use in the Food and Waters business, taking a big step into the future and expanding our already wide offer of testing.

MALDI-TOF reduces most confirmation tests from days to minutes, shortening or completely eliminating the uncertainty associated with a presumptive result and giving our customers the chance to act with confidence on a confirmed result – removing those few days of stress previously experienced whilst waiting for confirmation. This rapid test is particularly beneficial for foods requiring positive release.

With this groundbreaking achievement ALcontrol gives you results that are: 

Fast 

Allows your presumptive samples to be confirmed the same day for culture tests or overnight for rapid tests, greatly reducing the uncertainty associated with the presumptive stage

Sure

This exceptionally reliable technique has been proven to stringent UKAS / ISO17025 standards

Reliable

ALcontrol have demonstrated that this technology is not influenced by culture conditions, matrix type, stress levels and whether the strain is typical or atypical. Results from bacteria that had been grown under the most optimal purity conditions were compared with those obtained from cultures originating from live samples that had undergone several incubation steps and changes of media, with no appreciable difference.

Robust

The simplicity of the technique, its independence from bacterial metabolic stages, the proven reliability of the results and its accuracy in identifying difficult organisms to species level make it one of the most robust confirmation technologies available.

Enhanced

The MALDI-TOF database in use contains 9 species of Listeria, increasing the accuracy of the analysis from the traditional 6 species. This  allows us to report on nine species using this rapid method where on the current method we would only report on six – the remaining species would be reported as Listeria spp. 

Flexible

Due to the wide variety of applications, its ability to identify bacteria down to species level and the possibility of in-depth analysis beyond the species to identify particular strains, MALDI-TOF is invaluable for custom investigative work in the case of outbreaks or reoccurring problems.

Background

A technology developed in the late 80s, MALDI-TOF did not have widespread usage until the early 2000s due to the lack of a suitably sized instrument and of established standard operating procedures. Ever since then there has been increasing use in the clinical environment, where its speed and reliability have provided a much needed tool for the rapid identification of bacteria in patients in a field where faster results mean saved lives. In 2013, Clark et al. defined it as a “paradigm-shifting, rapid, and robust method for accurate microbial identification”.

MALDI-TOF is a type of “soft” (or “mild”) mass spectrometry. The sample is placed on to a target plate and covered with a matrix before being bombarded by a laser beam. The laser’s energy is absorbed by the matrix and then released gently. This allows the proteins present in the sample to pass into gaseous form (desorption) and become charged (ionization) without being broken down into their building blocks, as they would be in traditional mass spectrometry methods.

The ionized molecules generated through this process are then fired through a tube with a detector at the end. Because the tube is under high vacuum the only variable that will influence the time these molecules take to reach the detector is mass. This allows the instrument to create a spectrum depicting the mass and numbers of each of the molecules that are put through the process and that fit the mass range specified.

For species level identification the protein size range detected is generally between 2 and 20 kDa (kilodaltons). This range is dominated by ribosomal proteins, which are found to be very stable, ionize well, provide reproducible spectra and are only minimally influenced by microbial growth conditions unlike many cell-wall associated proteins which can vary in levels of expression under different culture conditions.

The spectra obtained through this process are then processed by software similar to the ones used by police forces around the world for fingerprint identification and compared to a database of known spectra, resulting in an ID in less than five minutes. The database currently contains almost 6,000 species and is continuously being improved and enlarged.

ALcontrol Laboratories offer this technique for advanced, rapid Listeria confirmation and has UKAS accreditation for the use of this robust technique on routine food samples. After passing the stringent UKAS / ISO17025 accreditation methods not only have ALcontrol proved that MALDI-TOF is equivalent to our traditional methods for accuracy and reliability but we have also demonstrated that it performs even better. This reliable technique is much better at dealing with atypical strains and difficult matrix types than the current standard methods. Because the test can be used directly from the selective media MALDI-TOF virtually eliminates the presumptive stage for all traditional/cultural tests and significantly shortens the presumptive stage for rapid methods.

In summary

This technique brings the reliability and speed of mass spectrometry to microbiology, shortening or eliminating the presumptive stage for many test types, removing the problems associated with lengthy culture stages and biochemical tests and allowing your results to be faster, more accurate and more reliable – providing you with the confidence to act quickly.

 

Stop presuming... start acting! Find out how by contacting us at:

 

Email: experts@alcontrol.com | Tel: 08450 738808

 

Click here to read the most recent guidance, aimed at healthcare and social care organisations, to help reduce the risk of vulnerable groups in their care contracting listeriosis.