Santamaría Johanna, López Liliana, Soto Carlos Yesid
Environmental Microbiology Laboratory, Department of Biology and Environmental Sciences, University Jorge Tadeo Lozano Bogotá, Colombia.
Front Microbiol. 2011 Dec 14;2:252. doi: 10.3389/fmicb.2011.00252. eCollection 2011.
Grassland-based production systems use ∼26% of land surface on earth. However, there are no evaluations of these systems as a source of antibiotic pollution. This study was conducted to evaluate the presence, diversity, and distribution of tetracycline resistance genes in the grasslands of the Colombian Andes, where administration of antibiotics to animals is limited to treat disease and growth promoters are not included in animals' diet. Animal (ruminal fluid and feces) and environmental (soil and water) samples were collected from different dairy cattle farms and evaluated by PCR for the genes tet(M), tet(O), tetB(P), tet(Q), tet(W), tet(S), tet(T), otr(A), which encode ribosomal protection proteins (RPPs), and the genes tet(A), tet(B), tet(D), tet(H), tet(J), and tet(Z), encoding efflux pumps. A wide distribution and high frequency for genes tet(W) and tet(Q) were found in both sample types. Genes tet(O) and tetB(P), detected in high frequencies in feces, were detected in low frequencies or not detected at all in the environment. Other genes encoding RPPs, such as tet(M), tet(S), and tet(T), were detected at very low frequencies and restricted distributions. Genes encoding efflux pumps were not common in this region, and only two of them, tet(B) and tet(Z), were detected. DGGE-PCR followed by comparative sequence analysis of tet(W) and tet(Q) showed that the sequences detected in animals did not differ from those coming from soil and water. Finally, the farms sampled in this study showed more than 50% similarity in relation to the tet genes detected. In conclusion, there was a remarkable presence of tet genes in these production systems and, although not all genes detected in animal reservoirs were detected in the environment, there is a predominant distribution of tet(W) and tet(Q) in both animal and environmental reservoirs. Sequence similarity analysis suggests the transmission of these genes from animals to the environment.
基于草原的生产系统占用了地球上约26%的陆地表面。然而，尚未有对这些系统作为抗生素污染来源的评估。本研究旨在评估哥伦比亚安第斯山脉草原中四环素抗性基因的存在、多样性和分布情况，该地区对动物使用抗生素仅限于治疗疾病，且动物饮食中不包含生长促进剂。从不同奶牛场采集动物（瘤胃液和粪便）和环境（土壤和水）样本，通过PCR检测tet(M)、tet(O)、tetB(P)、tet(Q)、tet(W)、tet(S)、tet(T)、otr(A)等编码核糖体保护蛋白（RPPs）的基因，以及tet(A)、tet(B)、tet(D)、tet(H)、tet(J)和tet(Z)等编码外排泵的基因。在两种样本类型中均发现tet(W)和tet(Q)基因分布广泛且频率较高。在粪便中高频检测到的tet(O)和tetB(P)基因，在环境中检测频率较低或根本未检测到。其他编码RPPs的基因，如tet(M)、tet(S)和tet(T)，检测频率极低且分布受限。编码外排泵的基因在该地区并不常见，仅检测到其中两个，即tet(B)和tet(Z)。对tet(W)和tet(Q)进行变性梯度凝胶电泳-聚合酶链反应（DGGE-PCR）并随后进行比较序列分析表明，在动物中检测到的序列与来自土壤和水的序列没有差异。最后，本研究中采样的农场在检测到的tet基因方面显示出超过50%的相似性。总之，这些生产系统中tet基因大量存在，尽管并非在动物宿主中检测到的所有基因在环境中都能检测到，但tet(W)和tet(Q)在动物和环境宿主中均占主导分布。序列相似性分析表明这些基因从动物传播到环境。
