Brady M S, Katz S E
Rutgers University, Cook College, Department of Biochemistry and Microbiology, New Brunswick, NJ 08903.
J Assoc Off Anal Chem. 1988 Mar-Apr;71(2):299-301.
An analytical system was developed which can assess the ability of antibiotic/antimicrobial residues (0.01-1.00 ppm) to affect the conjugal transfer of resistance among the Enterobacteriaceae. The donor strain, Escherichia coli RP-4 (Amr Tcr Nmr Kmr Lac+), and recipient strain, E. coli Sc-8632 (Smr Lac-), were incubated together in a 1:9 donor:recipient ratio for 18 h with gentle shaking (50 rpm) in brain heart infusion broth in the presence of residue levels of antibiotics. The mating cultures were serially diluted and spread-plated onto MacConkey agar containing 25 micrograms streptomycin/mL to select the total recipient population of sensitive E. coli Sc-8632 and transconjugants. After an 18 h incubation at 37 degrees C, the plates were replicated onto MacConkey agar containing 25 micrograms ampicillin/mL to select the ampicillin-resistant transconjugant population. Repeatability was good; the average transfer was 51.8%, with a coefficient of variation of 9.3%. Residue levels of tylosin (0.10 and 1.00 ppm) increased the transfer of the ampicillin marker beyond the 95% confidence limits. Oxytetracycline, bacitracin, streptomycin, penicillin, and virginiamycin did not increase the percent transfer. Oxytetracycline at 0.01 ppm decreased the percent transfer. In general, residue levels of antibiotics (0.01-1.00 ppm) did not affect the conjugal transfer of antibiotic resistance.
开发了一种分析系统，该系统可以评估抗生素/抗菌残留（0.01 - 1.00 ppm）影响肠杆菌科细菌间耐药性接合转移的能力。供体菌株大肠杆菌RP - 4（Amr Tcr Nmr Kmr Lac +）和受体菌株大肠杆菌Sc - 8632（Smr Lac -）以1:9的供体:受体比例在含有抗生素残留水平的脑心浸液肉汤中轻轻振荡（50 rpm）一起孵育18小时。将交配培养物连续稀释并涂布在含有25微克链霉素/毫升的麦康凯琼脂上，以选择敏感的大肠杆菌Sc - 8632和接合子的总受体群体。在37℃孵育18小时后，将平板复制到含有25微克氨苄青霉素/毫升的麦康凯琼脂上，以选择耐氨苄青霉素的接合子群体。重复性良好；平均转移率为51.8%，变异系数为9.3%。泰乐菌素的残留水平（0.10和1.00 ppm）使氨苄青霉素标记的转移超出了95%置信限。土霉素、杆菌肽、链霉素、青霉素和维吉尼亚霉素没有增加转移百分比。0.01 ppm的土霉素降低了转移百分比。一般来说，抗生素残留水平（0.01 - 1.00 ppm）不影响抗生素耐药性的接合转移。
