Risk assessment of ciprofloxacin, flavomycin, olaquindox and colistin sulfate based on microbiological impact on human gut biota.

Trace levels of veterinary antibiotics that reside in livestock products may disturb the balance of human intestinal microbiota and impair the colonized barrier function, which is critical to protect against the invasion or overgrowth of exogenous pathogens. We investigated the colonization barrier disruption effect of ciprofloxacin, flavomycin, olaquindox and colistin sulfate by the minimum inhibitory concentration (MIC) assay in pure culture of human gut bacteria and evaluated the no-observed-effect-concentration (NOEC) and acceptable daily intake (ADI) based on the microbiological impact. MICs of the antibiotics were tested for total 100 isolates composed of 10 isolates from each of 10 predominant genera of human faeces that were freshly collected from healthy women at 1x10(5) and 1x10(9) colony-forming units (CFU)/ml. MIC assay was also conducted with 10 ATCC standard bacteria species of human fecal microbiota for the comparison with freshly isolated human fecal mirobiota. The most susceptible bacteria were Escherichia coli for ciprofloxacin and colistin sulfate, Fusobacterium spp. for flavomycin and Eubacterium spp. for olaquindox. MIC values were lower at 1x10(5) than at 1x10(9)CFU/ml. The susceptibility of feacal microbiota freshly isolated from healthy women tended to be similar with those of ATCC standard bactera. NOEC (microg/ml) and ADI (microg/kg BW/day) were evaluated as 0.008 and 0.15 for ciprofloxacin, 0.25 and 1 for flavomycin, 0.125 and 3 for olaquindox and 1.0 and 7 for colistin sulfate, respectively.

[Morphological changes in broilers produced by feeding antibiotics]. / Morfologichni promeni u broileri, poluchavali s khranata nutritivni antibiotitsi.

Morphologic studies were carried out on the liver, kidneys, and small intestine of broiler birds that had been given antibiotics with the feed (virginiamycin, 20.0 ppm, flavomycin, 4.8 ppm, and avotan, 10.0 ppm) in the course of 49 days, kept with a group of controls. The liver of the test birds showed protein and fatty dystrophy, and the kidneys--protein dystrophy. The small intestine showed thinning of the wall and increase in the villi intestinales length. The manifestation of the morphologic changes depended on the amount of the antibiotic taken in. Those of the birds that were offered flavomycin had well manifested lesions, while in birds that were given virginiamycin and avotan only the lesions were more slightly expressed.