The prevalence, antibiotic resistance and biofilm formation ability of Enterococcus spp. isolated from food products in Algeria

Enterococci are ubiquitous bacteria in the normal intestinal microbiota of both humans and animals. They can be used in the food industry as starter or probiotic cultures. However, some species have emerged as an important nosocomial pathogens, and have been implicated in severe multi-resistant infections. In this study, a total of 235 food products were analyzed for the presence of Enterococcus spp. Overall, 54 (22.9%) out of the 235 samples were contaminated and 54 strains were isolated. The latter were identified by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and tested for antibiotic susceptibility against seven antibiotic molecules, in addition to their ability to form a biofilm. The predominant species was Enterococcus faecalis (70.4%), followed by Enterococcus hirae (12.9%), Enterococcus faecium (11.1%) and Enterococcus durans (5.5%). The highest resistance profile was ascribed to tetracycline (66.7%) and penicillin G (33.3%). Six enterococcal isolates (11.1%) were resistant to at least three antibiotic families. All isolated strains were able to form a biofilm and exhibited gelatinase activity. However, only 4 (7.4%) were β-hemolytic. This study revealed that food products might play a role in the spread of enterococci through the food chain to humans with these virulence and resistance characteristics. As a result, continuous investigations are necessary to assess the health hazards associated with the consumption of contaminated food products.