Occurrence of antibiotic resistance genes in the fecal DNA of healthy omnivores, ovo-lacto vegetarians and vegans

Scope: The effects of long-term omnivore, ovo-lacto vegetarian and vegan diets on the occurrence of 12 antibiotic resistance (AR) genes in the human gut were studied. Methods and results: The feces of 144 healthy volunteers recruited from Turin, Bari, Bologna, and Parma were screened for the occurrence of genes conferring resistance to tetracyclines, macrolide-lincosamide-streptogramin B, vancomycin, and β-lactams. Overall, erm(B), tet(W) and tet(M) were detected at the highest frequency. A low effect from the diet on the AR gene distribution emerged, with tet(K) and vanB occurring at a lower and higher frequency in vegans and omnivores, respectively. A correlation of the intake of eggs, milk from animal sources and cheese with an increased occurrence of tet(K) was observed, together with a higher incidence of vanB in consumers of eggs, poultry meat, fish and seafood. When the detection frequencies of AR genes in volunteers from Bari and the other sites were comparatively evaluated, a north-to-south gradient was observed, whereas no effect of sex or age was highlighted. Except for tet(K), a negligible three-factor interaction was seen. Conclusion: A high impact of the geographical location on AR gene distribution was seen in the cohort of subjects analyzed, irrespective of their dietary habits.