Lin Y, Zhao W, Shi Z D, Gu H R, Zhang X T, Ji X, Zou X T, Gong J S, Yao W
College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu, China.
Key Laboratory of Animal Breeding and Reproduction, Institute of Livestock Science, Jiangsu Academy of Agricultural Sciences, Jiangsu, China.
Poult Sci. 2017 Apr 1;96(4):997-1006. doi: 10.3382/ps/pew368.
Meat duck deep litter is considered to be an ideal environment for the evolution of bacterial antibiotic resistance if it is under poor management. The aim of this study was to characterize the accumulation of antibiotics and heavy metals in the deep litter and their role in the persistence of antibiotic resistance of Escherichia coli, and evaluate the service life of the deep litter. Samples were collected from initial, middle, and final stages of deep litter within 3 barns (zero, 4, and 8 rounds of meat duck fattening, d 34) and 9 flocks, with known consumption of antibiotics in the controlled trail. The feed and litter levels of consumed antibiotics and heavy metals were measured. E. coli (n = 147) was isolated and typed by Eric-PCR and the phylogenetic grouping technique, while minimal inhibitory concentrations of antibiotics and heavy metals were measured. This study confirmed the continuous accumulation of doxycycline and many heavy metals in the deep litter. The population of resistant certain bacteria to doxycycline (16 mg/L, 100 mg/L) or ofloxacin (8 g/mL, 50 g/mL) increased in the used deep litter (rounds 4 and 8). E. coli isolated from the 3 stages of sampling were highly resistant to ampicillin, tetracycline, florfenicol, and doxycycline. Increased resistance to ceftiofur, enrofloxacin, ofloxacin, and gentamicin were seen in the isolates from the final stage of deep litter. In addition, the percentage of isolates tolerant to zinc, copper, and cadmium and the numbers of Group-B2 isolates all increased in the used deep litter, and the isolates of each stage belonged predominantly to commensal groups. The antibiotic resistance of isolates with identical Eric-PCR patterns had improved from round 4 to 8, and differences still existed in the resistance profiles of isolates with identical Eric-PCR patterns from different barns of the same round. This study concluded that deep litter could be suitable for the evolution of bacterial antibiotic-resistance under conditions of continuous usage or accumulation of antibiotics and heavy metals without proper management.
如果管理不善，肉鸭厚垫料被认为是细菌抗生素耐药性演变的理想环境。本研究的目的是表征厚垫料中抗生素和重金属的积累情况及其在大肠杆菌抗生素耐药性持续存在中的作用，并评估厚垫料的使用寿命。在3个鸭舍（0、4和8轮肉鸭育肥，第34天）和9个鸭群的厚垫料初始、中期和末期阶段采集样本，已知在对照试验中抗生素的使用情况。测量了消耗的抗生素和重金属在饲料和垫料中的含量。通过Eric-PCR和系统发育分组技术分离并分型大肠杆菌（n = 147），同时测量抗生素和重金属的最低抑菌浓度。本研究证实了强力霉素和许多重金属在厚垫料中的持续积累。在使用过的厚垫料（第4轮和第8轮）中，对强力霉素（16 mg/L，100 mg/L）或氧氟沙星（8 μg/mL，50 μg/mL）耐药的某些细菌种群增加。从3个采样阶段分离出的大肠杆菌对氨苄青霉素、四环素、氟苯尼考和强力霉素高度耐药。在厚垫料末期分离出的菌株中，对头孢噻呋、恩诺沙星、氧氟沙星和庆大霉素的耐药性增加。此外，在使用过的厚垫料中，对锌、铜和镉耐受的分离株百分比以及B2组分离株的数量均增加，且各阶段的分离株主要属于共生菌群。具有相同Eric-PCR模式的分离株的抗生素耐药性从第4轮到第8轮有所提高，并且在同一轮不同鸭舍中具有相同Eric-PCR模式的分离株的耐药谱仍存在差异。本研究得出结论，在抗生素和重金属持续使用或积累且管理不当的情况下，厚垫料可能适合细菌抗生素耐药性的演变。
