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标题：Low prevalence of bla TEM genes in Arctic environments and agricultural soil and rhizosphere
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作者：Lorenzo Brusetti ; Trine Glad ; Sara Borin 等
期刊名称：Microbial Ecology in Health and Disease
印刷版ISSN：1651-2235
出版年度：2009
卷号：20
期号：1
页码：27-36
DOI：10.1080/08910600701838244
出版社：Microbial Ecology in Health and Disease
摘要：The prevalence of bla_TEM genes conferring ampicillin resistance (Amp^r) in different soils was determined to clarify the environmental distribution of resistance determinants of major clinical importance. Samples were collected from 14 sites in New Zealand, mainland Norway, Svalbard, and 2 soil microcosms made of compost purchased in Italy. The Amp^r bacteria represented 1.7–100% of the cultivable microflora with an average of 28%. Approximately 1200 Amp^r isolates were further analyzed. Although >50% of the resistant isolates were capable of β-lactam-ring (nitrocefin) degradation, none carried a PCR-detectable bla_TEM gene. The proportion of bla_TEM genes in the culturable Amp^r isolates was <0.07%. The overall bla_TEM gene prevalence was determined by bla_TEM-specific PCR of DNA extracted directly from the environmental sample. DNA hybridization was performed on selected samples with a detection limit of ∼11 bla_TEM genes per PCR sample. Our analysis indicates that the prevalence of bla_TEM carrying bacteria is <1 per 1000 to 100 000 bacteria in the samples analyzed. The study suggests that bla_TEM genes are rare in soil environments, in contrast to their increasing prevalence in some clinical and commensal bacterial populations. The frequent observation of nitrocefin-degrading capacity among the sampled isolates suggests that other mechanisms conferring enzyme-mediated resistance to β-lactam antibiotics are widespread in Arctic and agricultural soil environments.
关键词：ampicillin resistance ; blaTEM alleles ; non-selective environments ; natural reservoirs ; soil ; geographic distribution