Are archobacteria a threat to human health?

The increase in the finding of bacteria of the Arcobacter genus in food samples of all kinds raises public health concerns, since very little is still known about the pathogenic potential of the Arcobacter species; and the few studies that have been carried out on the subject show a large number of host species and transmission routes. In addition, there are already several species of the Arcobacter genus considered as emerging food pathogens and it is believed that they may be the cause of some cases of gastrointestinal diseases.

In order to find out the risk associated with the presence of these bacteria in food, the MikroIker team from the Department of Immunology, Microbiology and Parasitology of the University of the Basque Country (UPV/EHU) is working on a line of research focused on the prevalence and characterization of bacteria of the genus Arcobacter with a large number of food samples (seafood, vegetables, meat products and fresh cheese). In addition, they have studied the ability of these bacteria to adhere to different surfaces frequently found in food processing environments.

“The objective of this work is, on the one hand, to determine the presence of this pathogen in a wide range of products never studied until now; on the other hand, to evaluate the genetic diversity and the presence of virulence genes; and finally, to observe the ability of these pathogens to remain adhered to a surface, such as glass, plastic or steel, which are commonly found in food processing materials and environments”, says Irati Martinez Malax-Etxebarria, Researcher at the Department of Immunology, Microbiology and Parasitology of the Faculty of Pharmacy of the UPV/EHU.

Members of the research team. (Photo: UPV/EHU)

A total of 220 samples from three large food groups were analyzed: farm animals, marine animals and vegetables. “Arcobacter was detected in 22.3% of the samples analyzed and the most abundant species in all of them was A. butzleri, the species most often associated with human diseases, although other species also appeared”, indicates the researcher from the UPV/EHU. “We saw that all species had genes associated with virulent capacities, that is, genes that could give the bacteria the ability to cause infections and diseases in humans,” explains Irati Martinez.

Likewise, “we observed that baby squid are an important source of Arcobacter, so that raw consumption of these products could be an important source of infection for humans. We also detected some cases in a piece of fresh cheese, probably associated with cross-contamination since it was a product purchased at the cut”, adds the author of the work. “In the vegetables analyzed (lettuce, spinach, carrot, chard…) —continues Martinez Malax-etxebarria— the bacteria appeared in all types except chard. Interestingly, all the lettuce and Swiss chard that tested positive were packaged. That makes us think a bit, because many times when we buy processed foods we do not pay attention to its cleanliness. In addition, in carrots we detected a species that had never been characterized until now and that also has virulence genes”.

Furthermore, “the results confirm the formation of biofilms by foodborne Arcobacter bacteria on different food contact surfaces. Under the conditions in which we have carried out our tests, we have observed that glass surfaces favor the survival and growth of bacteria”, comments the UPV/EHU researcher.

According to Irati Martinez, “this is the first time that the presence of Arcobacter species in fresh cheese from Burgos and carrots has been reported. In addition, we point to shellfish, especially squid, as an important source of adherent archobacteria.” “These findings must be considered due to their possible implications for food safety, since Burgos cheese is a ready-to-eat product, and carrots and shellfish are frequently consumed undercooked or raw”, adds the UPV researcher/ EHU.

The study is titled “Genetic characterization and biofilm formation of potentially pathogenic foodborne Arcobacter isolates”. And it has been published in the academic journal International Journal of Food Microbiology. (Source: UPV/EHU)