3M sets sights on Cronobacter with detection test

The 3M Molecular Detection Assay 2 – Cronobacter delivers results for samples between 10 and 300g in size and after 18 hours of enrichment.

The firm said this range was chosen during assay development after feedback from manufacturers and testing laboratories.

Cronobacter species, formerly known as Enterobacter sakazakii​, is a group of bacteria found in the environment associated with contaminated powdered infant formula, powdered milk, herbal teas and starches.

Cronobacter has been shown to persist up to two years in powdered infant formula, and testing in these products is required by the US Food and Drug Administration (FDA).

The moving target​

John David, chief scientific marketing manager at 3M Food Safety, said Cronobacter spp. has been a “moving target” over the years. 

“​This group of organisms was formerly known as Enterobacter sakazakii, and within recent years has been reclassified twice. Today, there are seven species of Cronobacter (​C. sakazakii, C. malonaticus, C. turicensis, C. muytjensii, C. dublinensis, C. condiment, and C. universalis)," ​he told FoodQualityNews.

“The development of the assay involved advanced bioinformatics to design the DNA primers to specifically recognize these seven species according with the most recent classification.”​

He added while regulations or guidelines exist in countries including Australia, New Zealand, Canada, China, Argentina, Mexico and the EU, the rapid growth of the infant formula market and increasing consumer health awareness means other countries are considering legislation.

While Cronobacter infection is less common than Salmonella, Listeria monocytogenes and E. coli O157, it impacts a very vulnerable population and has a high mortality rate in the range of 40%, according to the Centers for Disease Control and Prevention (CDC).

CDC said it usually hears about four to six babies getting it each year but does not get told of every case.

Versus agar and PCR-based methods​

3M said the isothermal molecular assay overcomes the limitations of conventional agar and PCR-based methods with ready-to-use reagents and a workflow with only two transfer steps.

“PCR-based methods can have susceptibility to sample matrix interferences, complicated workflows required reagent preparation, and, depending on the design of the PCR primers, cross-reactivity with non-Cronobacter species,” ​said David.

“The 3M Molecular Detection Assay 2 – Cronobacter is robust, using an advanced nanotechnology-based lysis solution to clean the sample, combined with a unique Bst DNA polymerase which has been shown to be less sensitive to interferences than the Taq polymerase used in PCR.”​

After performing the assay protocol, samples are placed in the 3M Molecular Detection Instrument for DNA amplification and detection. 

Results are interpreted by the 3M Molecular Detection Software and presented with color-coded icons.

Positives are reported in real-time, as early as 15 minutes after the run is started and negatives are provided in 60 minutes.

The product joins four other assays (Salmonella, E. coli O157 (including H7), Listeria and Listeria monocytogenes) as part of the 3M Molecular Detection System pathogen testing platform.

The platform is used by food processors, universities, governments and contract testing laboratories in more than 40 countries.