Centre for Biological Sciences, University of Southampton, Highfield Campus, Southampton, United Kingdom.
mBio. 2012 Nov 27;3(6):e00489-12. doi: 10.1128/mBio.00489-12.
Horizontal gene transfer (HGT) is largely responsible for increasing the incidence of antibiotic-resistant infections worldwide. While studies have focused on HGT in vivo, this work investigates whether the ability of pathogens to persist in the environment, particularly on touch surfaces, may also play an important role. Escherichia coli, virulent clone ST131, and Klebsiella pneumoniae harboring extended-spectrum-β-lactamase (ESBL) bla(CTX-M-15) and metallo-β-lactamase bla(NDM-1), respectively, exhibited prolonged survival on stainless steel, with approximately 10(4) viable cells remaining from an inoculum of 10(7) CFU per cm(2) after 1 month at 21°C. HGT of bla to an antibiotic-sensitive but azide-resistant recipient E. coli strain occurred on stainless steel dry touch surfaces and in suspension but not on dry copper. The conjugation frequency was approximately 10 to 50 times greater and occurred immediately, and resulting transconjugants were more stable with ESBL E. coli as the donor cell than with K. pneumoniae, but bla(NDM-1) transfer increased with time. Transconjugants also exhibited the same resistance profile as the donor, suggesting multiple gene transfer. Rapid death, inhibition of respiration, and destruction of genomic and plasmid DNA of both pathogens occurred on copper alloys accompanied by a reduction in bla copy number. Naked E. coli DNA degraded on copper at 21°C and 37°C but slowly at 4°C, suggesting a direct role for the metal. Persistence of viable pathogenic bacteria on touch surfaces may not only increase the risk of infection transmission but may also contribute to the spread of antibiotic resistance by HGT. The use of copper alloys as antimicrobial touch surfaces may help reduce infection and HGT.
Horizontal gene transfer (HGT) conferring resistance to many classes of antimicrobials has resulted in a worldwide epidemic of nosocomial and community infections caused by multidrug-resistant microorganisms, leading to suggestions that we are in effect returning to the preantibiotic era. While studies have focused on HGT in vivo, this work investigates whether the ability of pathogens to persist in the environment, particularly on touch surfaces, may also play an important role. Here we show prolonged (several-week) survival of multidrug-resistant Escherichia coli and Klebsiella pneumoniae on stainless steel surfaces. Plasmid-mediated HGT of β-lactamase genes to an azide-resistant recipient E. coli strain occurred when the donor and recipient cells were mixed together on stainless steel and in suspension but not on copper surfaces. In addition, rapid death of both antibiotic-resistant strains and destruction of plasmid and genomic DNA were observed on copper and copper alloy surfaces, which could be useful in the prevention of infection spread and gene transfer.
水平基因转移（HGT）是导致全球范围内抗生素耐药性感染发生率增加的主要原因。虽然已有研究集中于体内的 HGT，但本研究调查了病原体在环境中（尤其是在接触表面）的持久性是否也可能发挥重要作用。携带扩展型β-内酰胺酶（ESBL）bla（CTX-M-15）的大肠杆菌、强毒克隆 ST131 和携带金属-β-内酰胺酶 bla（NDM-1）的肺炎克雷伯菌在不锈钢表面的存活时间延长，在 21°C 下 1 个月后，从 10 7 CFU/cm 2 的接种物中仍有约 10 4 个活细胞。bla 在不锈钢干接触表面和悬浮液中转移到抗生素敏感但叠氮化物抗性的受体大肠杆菌菌株中，但不在干燥的铜表面转移。接合频率约为 10 到 50 倍，并且立即发生，并且 ESBL 大肠杆菌作为供体细胞时产生的转导子比肺炎克雷伯菌更稳定，但 bla（NDM-1）转移随着时间的推移而增加。转导子也表现出与供体相同的耐药谱，表明存在多种基因转移。在铜合金上，两种病原体的快速死亡、呼吸抑制以及基因组和质粒 DNA 的破坏伴随着 bla 拷贝数的减少而发生。裸露的大肠杆菌 DNA 在 21°C 和 37°C 时在铜上降解，但在 4°C 时缓慢降解，这表明金属起直接作用。致病细菌在接触表面上的存活不仅会增加感染传播的风险，而且还可能通过 HGT 促进抗生素耐药性的传播。使用铜合金作为抗菌接触表面可能有助于减少感染和 HGT。
水平基因转移（HGT）赋予了对许多类抗生素的抗性，导致了由多药耐药微生物引起的医院内和社区感染的全球流行，这导致人们提出我们实际上正在回到抗生素前时代。虽然已有研究集中于体内的 HGT，但本研究调查了病原体在环境中（尤其是在接触表面）的持久性是否也可能发挥重要作用。在这里，我们显示出耐多药大肠杆菌和肺炎克雷伯菌在不锈钢表面上的长时间（数周）存活。当供体和受体细胞在不锈钢上和悬浮液中混合时，bla 基因的质粒介导的 HGT 发生在对叠氮化物具有抗性的受体大肠杆菌菌株中，但不在铜表面上发生。此外，在铜和铜合金表面上观察到两种抗生素耐药菌株的快速死亡以及质粒和基因组 DNA 的破坏，这可能有助于预防感染的传播和基因转移。
