UPV/EHU's MikroIker team researchers Irati Martinez Malaxetxebarria and Adrián Salazar. Credit: Nuria González, UPV/EHU
Several species of the bacteria genus Arcobacter are considered to be emerging food pathogens and have the potential to cause illness when consumed through contaminated food or water. However, little is yet known about the pathogenic potential or the prevalence of Arcobacter species in a range of different retail food products. A recent study at the University of the Basque Country (UPV/EHU) sought to assess the risk associated with Arcobacter bacteria in food by testing a wide range of different food products for the presence of the bacteria, evaluating the genetic diversity and presence of virulence genes in recovered isolates, and observing the biofilm activity of the isolates on surfaces such as glass, plastic and steel.
The researchers tested a total of 220 food samples, which included terrestrial animal meats (such as turkey and rabbit), seafoods (including squid and shrimp) and vegetables, as well as fresh cheese. Arcobacter species were identified through polymerase chain reaction (PCR) techniques and further genetically characterized by Multilocus Sequence Typing (MLST) and detection of specific virulence-associated genes. The team assessed the isolates’ abilities to form biofilms both by testing for biofilm-associated genes and performing in vitro static biofilm assays on borosilicate glass, stainless steel and polystyrene surfaces.
The team found bacteria of the Arcobacter genus in 22.3% of the samples, with the most abundant species being A. butzleri, which is also the species most often associated with human disorders, said first author Irati Martinez-Malaxetxebarria, a researcher in the MikroIker team of UPV/EHU's Department of Immunology, Microbiology and Parasitology. All but one of the isolates recovered were found to possess virulence genes. Of the food types tested, baby squid was found to be a major source of Arcobacter, suggesting that raw consumption of such products could be a significant source of human infection, Martinez-Malexetxebarria noted.
Additionally, Arcobacter was detected in all of the vegetable types tested except for Swiss chard. Martinez-Malaxetxebarria noted that all of the vegetable samples that tested positive, including carrots, spinach and lettuce, were pre-packaged, suggesting possible contamination at some point in the processing or packing process. In biofilm assays, the team observed the greatest biofilm activity on glass surfaces and hypothesized that glass surfaces could contribute to the survival and cross-contamination of Arcobacter in food processing environments. The study also established the presence of Arcobacter species in carrots and fresh Burgos cheese for the first time. This research was published in the International Journal of Food Microbiology.
The study highlighted the wide range of retail food products that can harbor potentially pathogenic Arcobacter species, the authors wrote, with a particular emphasis on read-to-eat or raw foods like cheese, vegetables and raw seafood.
“Future studies on the survival and growth ability of Arcoacter on these products, especially on ready to eat ones, may be of interest in order to assess the implications of these findings for food safety,” the authors wrote.