Residual antibiotics disrupt meat fermentation and increase risk of infection.

Fermented sausages, although presumed safe for consumption, sometimes cause serious bacterial infections in humans that may be deadly. Not much is known about why and when this is the case. We tested the hypothesis that residual veterinary antibiotics in meat can disrupt the fermentation process, giving pathogenic bacteria a chance to survive and multiply. We found that six commercially available starter cultures were susceptible to commonly used antibiotics, namely, oxytetracycline, penicillin, and erythromycin. In meat, statutorily tolerable levels of oxytetracycline and erythromycin inhibited fermentation performance of three and five of the six starter cultures, respectively. In model sausages, the disruption of meat fermentation enhanced survival of the pathogens Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium compared to successful fermentations. Our work reveals an overlooked risk associated with the presence of veterinary drugs in meat. Antibiotics have for a long time been used as growth promoters in farm animals, and while they are banned as such in Europe, their clinical use in farm animals still accounts for the majority of consumption. Here, we examined how acceptable levels of antibiotics in meat influence fermentation. Our results show that commonly used bacterial starter cultures are sensitive to residual antibiotics at or near statutorily tolerable levels, and as a result, processed sausages may indeed contain high levels of pathogens. Our findings provide a possible explanation for outbreaks and disease cases associated with consumption of fermented sausages and offer yet another argument for limiting the use of antimicrobials in farm animals.