Listeria monocytogenes is a fatal and common bacteria within the food processing industry. It significantly threatens the health of humans. SciTechDaily notes that it does not just lead to serious illnesses but that it is also gaining resistance toward measures to preserve food safety.
Intriguingly, two Listeria bacteria species, which were previously thought to be incapable of posing any risks, have been seen to harbor detrimental qualities as well, such as building up pathogen resistance that makes them resistant to disinfectants.
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Listeria Innocua: Harmless No More
A team of researchers, including Dr. Thendo Mafuna from the University of Johannesburg, conducted a whole genome sequencing study that revealed the altering qualities of Listeria that were spotted within the country. The study was included in the Microbiology Spectrum journal.
According to Phys, the research revealed that strains of Listeria innocua were becoming resistant to pH, temperature, dehydration, and other forms of stress. On top of this, the strains were also seen to have have hypervirulence, which is genetically the same as Listeria monocytogenes.
In the research, some strains of Listeria innocua as well as Listeria welshimeri exhibit resistance to a common disinfectant from the QAC or QUAT (Quaternary ammonium compound) chemical group. The researchers analyzed two Listeria innocua strains and observed that these strains gained at least three pathogenic qualities that are concerning. Such qualities include "CRISPR CAS-type adaptive immune systems," as noted by Phys.
The researchers sampled Listeria strains, which were non-pathogenic, in dried, processed, and raw meat within commercial food processing centers across the country. The study aligns with other research that reveals how non-pathogenic Listeria are developing resistance.
Listeria Innocua's Shared Genes With Pathogenic Listeria Monocytogenes
Dr. Mafuna notes that the Listeria innocua that the team tested were seen to have genes that are also present in Listeria monocytogenes. SciTechDaily also notes that the shared genes between the two are also attributed to the development of disease among humans. They are also attributed to tolerance to stress, like the disinfectant Benzalkonium chloride (BC or BAC) resistance.
Disinfectant Resistance
Benzalkonium chloride (BC or BAC) is part of a chemical group known as the QUATs (Quaternary Ammonium Compounds). Such chemical groups can be spotted across various disinfectants and have been seen to effectively terminate viruses, fungi, and bacteria.
Dr. Mafuna notes the need to assess South African facilities in order to understand what is taking place. The analysis of the said bacteria can help in projecting sequence types to monitor.
He also notes how concerning it is that strains of Listeria innocua share detrimental characteristics with Listeria monocytogenes.
SciTechDaily notes how food processors need to be wary of Listeria innocua because of their growing resistance to disinfectants commonly utilized to eradicate them. Dr. Mafuna also notes how it may be helpful to use various disinfectant types, as switching kinds could delay or prevent the development of resistance toward a specific disinfectant.
Dr. Mafuna notes how big players in the food processing industry may want to look deeper into the efficiency of BC or other quat disinfectants. They may do this by collecting swab samples before and after cleaning and culturing the swabs. This will help them see the effectiveness of their disinfectants.
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