图中为研究者在Pearlsian海湾，背景为洞穴中方解石的相关信息 (Credit: Copyright Max Wisshak)
近日，国际杂志PLoS One在线刊登了国外研究人员的最新研究成果，在文章中，来自麦克马斯特大学和阿克伦大学的研究者在新墨西哥的龙舌兰洞穴发现了一种普遍流行的抗生素抗性细菌，龙舌兰洞穴是世界上最深最大的洞穴，人类已经有超过四百万年没有与该洞穴接触了。
研究者Wright表示，抗生素抗药性和细菌之间的关系已经有亿万年了，但是我们紧紧是在过去的70年里才开始理解它们之间的这种关系。环境中有很多抗生素可以被找到来应对目前无法治愈的感染性疾病。研究者从洞穴壁上收集了许多细菌菌株，然后检测了这些细菌的耐药性，研究者发现没有一种细菌可以致病，而且这些细菌也没有一种暴露于人类所用的抗生素之中。所有菌株至少对一种抗生素有抗性，而且有些细菌对14种不同的抗生素也有抗性。
研究者也识别出了一种和能引起炭疽的细菌相关的抗性细菌，这种抗性原先在诊所中出现过。Barton教授表示，这样，我们就可以告诉医生，将来需要知道细菌存在的抗性，这样当这种细菌出现在诊所的时候，医生就可以知道如何应对了。细菌对抗生素耐药性的上升对于人类健康来说非常重要，当细菌出现，比如多重耐药性的金黄色葡萄球菌的出现，以至于任何药物都不能治疗的时候，那么这种细菌是如何获得耐药性的，这就成为我们必须思考的一个问题。
在个别情况下，这些微生物可以对7种甚至更多药物产生耐药性，而且用传统的药物根本无法治疗，这样一来，医生只能通过手术的方法切掉被感染的组织从而来抑制疾病的蔓延。实际上，在环境中发现的产生耐药性的菌株对人类是无害的。抗生素原本是在农业中使用的，一般我们很难发现一种环境，在这种环境中抗生素不能施加某种效应，但是在龙舌兰洞穴中，我们发现了自然界中抗生素抗性存在的库。龙舌兰洞穴自从1986年被发现，每年都限制研究者进入，这个洞穴被一层不透水的岩石层所环绕，意味着它可以储存至少10000年的水以使各种耐抗生素的细菌生存。（生物谷：T.Shen编译）
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doi:10.1371/journal.pone.0034953
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Antibiotic Resistance Is Prevalent in an Isolated Cave Microbiome
Kirandeep Bhullar1, Nicholas Waglechner1, Andrew Pawlowski1, Kalinka Koteva1, Eric D. Banks2, Michael D. Johnston2, Hazel A. Barton2, Gerard D. Wright1*
Antibiotic resistance is a global challenge that impacts all pharmaceutically used antibiotics. The origin of the genes associated with this resistance is of significant importance to our understanding of the evolution and dissemination of antibiotic resistance in pathogens. A growing body of evidence implicates environmental organisms as reservoirs of these resistance genes; however, the role of anthropogenic use of antibiotics in the emergence of these genes is controversial. We report a screen of a sample of the culturable microbiome of Lechuguilla Cave, New Mexico, in a region of the cave that has been isolated for over 4 million years. We report that, like surface microbes, these bacteria were highly resistant to antibiotics; some strains were resistant to 14 different commercially available antibiotics. Resistance was detected to a wide range of structurally different antibiotics including daptomycin, an antibiotic of last resort in the treatment of drug resistant Gram-positive pathogens. Enzyme-mediated mechanisms of resistance were also discovered for natural and semi-synthetic macrolide antibiotics via glycosylation and through a kinase-mediated phosphorylation mechanism. Sequencing of the genome of one of the resistant bacteria identified a macrolide kinase encoding gene and characterization of its product revealed it to be related to a known family of kinases circulating in modern drug resistant pathogens. The implications of this study are significant to our understanding of the prevalence of resistance, even in microbiomes isolated from human use of antibiotics. This supports a growing understanding that antibiotic resistance is natural, ancient, and hard wired in the microbial pangenome.
