Within the meals processing business, the lethal micro organism Listeria monocytogenes is monitored carefully. Not solely can the micro organism make folks extraordinarily ailing, it’s recognized to be growing resistance to varied meals security measures internationally.

Nonetheless, two ‘innocent’ species of Listeria are additionally growing a shocking variety of traits doubtlessly dangerous to people.

A Complete Genome Sequencing research in South Africa, from a group of researchers with first writer Dr Thendo Mafuna on the College of Johannesburg, exhibits a few of the altering traits of Listeria discovered within the nation.

The research exhibits that Listeria innocua strains are growing resistance to temperature, pH, dehydration and different stresses; in addition to hypervirulence genetically similar to that of Listeria monocytogenes.

Some strains of L. innocua and L. welshimeri within the research present all three genes for resistance to a widely-used disinfectant, from the quaternary ammonium compound (QAC or QUAT) group of chemical substances.

Two strains of L. innocua they analyzed have developed three or extra regarding pathogenic traits, together with CRISPR CAS-type adaptive immune programs.

The 2 non-pathogenic strains of Listeria have been sampled in uncooked, dried and processed meats at business meals processing amenities within the nation.

The research confirms different analysis displaying rising resistance in non-pathogenic Listeria species in different elements of the world.

Shared genes with pathogenic species

The Listeria innocua that we examined has a few of the genes which are additionally present in pathogenic Listeria monocytogenes.

Dr Thendo Mafuna, First Creator, College of Johannesburg

Mafuna is from the Division of Biochemistry on the College of Johannesburg.

These shared genes between L. innocua and L. monocytogenes are additionally liable for illness in people; and stress tolerance comparable to resistance to the disinfectant Benzalkonium chloride (BC or BAC).

Analysis from others has proven that although Listeriosis isn’t brought on by L. innocua, it does occur extra typically in folks with compromised immune programs, he provides.

Benzalkonium chloride (BAC) is a member of a gaggle of chemical substances referred to as Quaternary ammonium compounds, or QUATs. Quats are discovered in lots of frequent disinfectant merchandise. They’ve been proven to be extremely efficient at killing micro organism, fungi and viruses.

All of the L. innocua strains they examined additionally had the entire LIPI-4 hypervirulence gene sequence, which might trigger illness in people, he says. The LIPI-4 sequence they present in L. innocua is similar to that present in pathogenic L. monocytogenes, as recorded by the Pasteur Institute in Paris, France.

From uncooked, dried and processed meats

The samples and isolates analyzed on this research have been collected between 2014 and 2019 by the South African Authorities’s Division of Agriculture, Land Reform and Rural Improvement (DALRRD). These have been submitted to the Agricultural Analysis Council (ARC) at Onderstepoort Veterinary Analysis SA for evaluation.

In complete, 258 isolates from butcheries, abbatoirs, shops, chilly shops and processing amenities all around the nation have been studied. Of those, 38 have been discovered to be nonpathogenic L. Innocua; and one other three isolates discovered to be nonpathogenic L. welshimeri.

The isolates got here from uncooked entire, uncooked processed, dried, and processed cooked, beef, rooster and pork meats. Dr. Itumeleng Matle on the Bacteriology Division, ARC in Onderstepoort did the microbiological evaluation of Listeria isolation and identification.

The Complete Genome Sequencing (WGS) was carried out by Dr. Rian E. Pierneef on the ARC’s Biotechnology Platform at Onderstepoort.

Mafuna then in contrast the genome sequences with these recorded by the Pasteur Institute, in Paris, France; and carried out the evaluation for the research.

Looking out

“We have to take a look at our personal amenities in South Africa to essentially see what is occurring. Our analyses of those micro organism may help us predict which sequence sorts to be on the look out for,” says Mafuna.

It’s the variety of dangerous traits that the L. innocua strains share with L. monocytogenes that’s regarding, he provides.

Meals processors must look out for Listeria innocua as a result of it’s changing into immune to disinfectants which are utilized in business to do away with them. It could even be useful to attempt several types of disinfectants to surfaces, he says. Switching from one kind to a different could stop or delay the micro organism growing resistance to 1 kind of disinfectant.

“Large industrial meals processors could need to examine how environment friendly BC or quat disinfectants are of their amenities. This may be carried out by taking swabs earlier than cleansing and once more after cleansing, culturing these, to see how effectively the disinfectant regimes are working,” says Mafuna.


Journal reference:

Mafuna, T., et al. (2022) Comparative Genomics of Listeria Species Recovered from Meat and Meals Processing Services. Microbiology Spectrum. doi.org/10.1128/spectrum.01189-22.

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