TABLE 2.
Percentages of nodule isolates resistant to CTC, SMZ, and TYL from soils having received increasing concentrations of antibiotics
| Soil antibiotic treatment (mg · kg−1) | No. of isolates | % of resistant isolates in culture medium containing (mg · liter−1)a: |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| CTCb (1) | CTC (10) | CTC (100) | SMZc (1) | SMZ (10) | SMZ (100) | TYLd (1) | TYL (10) | TYL (100) | ||
| Control (0) | 51 | 100.0 | 97.2 | 10.9 | 100.0 | 100.0 | 60.8 | 100.0 | 71.9 A | 6.2 |
| Low dose (0.1) | 78 | 98.8 | 98.8 | 16.7 | 84.0 | 79.0 | 33.6 | 96.3 | 49.1 AB | 2.9 |
| Intermediate dose (1) | 79 | 98.8 | 91.2 | 15.5 | 91.7 | 88.1 | 33.4 | 100.0 | 47.3 AB | 3.7 |
| High dose (10) | 64 | 98.6 | 76.8 | 1.4 | 100.0 | 98.6 | 36.1 | 90.3 | 31.1 B | 3.0 |
| Pr > F | 0.800 | 0.236 | 0.692 | 0.564 | 0.598 | 0.164 | 0.538 | 0.062 | 0.881 | |
| Statistical significance at P value of 0.05 | NSe | NS | NS | NS | NS | NS | NS | Sf | NS | |
a
Data from each column were subjected to analysis of variance (ANOVA) followed by a Newman and Keuls test (P = 0.05) using XLSTAT-18.07 software (Addinsoft). Data followed by the same uppercase letter are not significantly different (P > 0.05).
b
CTC, chlortetracycline.
c
SMZ, sulfamethazine.
d
TYL, tylosin.
e
NS, no significant difference.
f
S, significant difference.