摘要：There is currently some concern regarding the possibility that consumption, by humans, of small quantities of veterinary antibiotics, present as residues in meat, might adversely alter the indigenous gut microflora. This study aimed to assess the potential effect on the human gut microflora of exposure to low levels of tilmicosin and spiramycin. Four groups of 4 human-flora-associated rats were dosed for 5 days with either water, tilmicosin (400 or 120 µg/kg/day) or spiramycin (500µg/kg/day). The experiment was repeated to improve statistical power and assess the reproducibility of effects. Total anaerobes in faeces were unaffected by any antibiotic treatment, whilst a transient increase in both number and proportion of total enterobacteria (p≥0.05) was observed only in rats given 400 µg/kg/day tilmicosin and in only one of the two experiments. Tilmicosin did not significantly increase the number, or proportion, of tilmicosin-resistant enterobacteria, whilst spiramycin significantly increased (p≥0.05) the number of spiramycin-resistant enterobacteria on the first 2 days of antibiotic treatment. Furthermore, a significant (p≥0.05) increase in the proportion of spiramycin-resistant enterobacteria was observed at the end of the antibiotic treatment period. The experimental design presented yields data which can justifiably be extrapolated to the human situation and which may be of greater relevance than that derived from MIC tests.Keywords: antibiotic residues, tilmicosin, spiramycin, gut microflora, EU regulations.
