TABLE 2.
Total and tetracycline-insensitive bacterial population levels in swine cecal contents and cecal tissue homogenates
| Sample | Chlortetra- cycline concn (μg/ml) | No. of viable bacteriaa ± SEM
|
|
|---|---|---|---|
| Farm A | Farm B | ||
| Cecal contents | 0 | 10.44 ± 0.065 | 10.18 ± 0.071 |
| 4 | 10.39 ± 0.066 | 10.18 ± 0.092 | |
| 16 | 10.17 ± 0.067A | 10.13 ± 0.083 | |
| 64 | 9.62 ± 0.093A,B | 10.12 ± 0.095B | |
| 128 | ND | 10.07 ± 0.041 | |
| 256 | 7.68 ± 0.140A,B | 9.68 ± 0.084A,B | |
| Cecal tissues | 0 | 7.24 ± 0.060 | 7.07 ± 0.132 |
| 4 | 7.25 ± 0.107 | 7.08 ± 0.143 | |
| 16 | 6.91 ± 0.163 | 7.11 ± 0.109 | |
| 64 | 6.38 ± 0.118A,B | 7.07 ± 0.112B | |
| 128 | ND | 6.80 ± 0.085 | |
| 256 | 5.07 ± 0.373A,B | 6.40 ± 0.014A,B | |
a
Values are average log10 bacterial counts for animals from each farm for cecal contents and cecal tissues. Farm A, seven swine fed a diet without tetracycline (or other antibiotics). Farm B, six swine fed a diet containing 400 g of chlortetracycline/ton. A, values are significantly (P ≤ 0.01) different from values of samples from the same farm and cultured on medium without antibiotic. B, values are significantly different between farms at the same antibiotic concentration. ND, not determined.