| The problem of bacterial resistance is becoming more and more serious and haslead to the global concern. The irrational use of antibiotics eventually caused theprevalence of "superbugs", which is a serious threat to the life and health of the globalanimal and people. NDM-1-producing Klebsiella pneumoniae which is a kind of"super bacteria" carries the NDM-1gene encoding the New Delhimetallo-β-lactamase(NDM-1). The strains producing New Delhi metallo-β-lactamase1(NDM-1) areresistant to almost all common antibiotics except for polymixin and tigecycline, whichis called "pan resistance". The "Superbugs" spread globally and limite the antibiotictherapy. Super bacteria bring great difficulties and challenges to clinical treatment.We not only should continue to adjust and standardize the proper use of antibiotics,but should also develop the novel antibacterial agents.Bacteriophages (phages) are viruses that specifically infect and lyse bacteria.Bacteriophages are present in the natural environment. Bacteriophages take advantageof holin-lysin to lyse host bacteria. Phage therapy may be a viable alternative orcomplement to traditional antibiotic treatment, Bacteriophages have incomparableadvantages compared with antibiotics: specificity, efficiency, no side effects, low cost,et al. Phage biological agents have extremely broad prospects for development in thetreatment of bacterial infections.The purpose of this study is to explore the application potential of phagetherapy against multi-resistant infections. Klebsiella pneumoniae ATCC BAA-2146was Purchased from the American Type Culture Collection Center (ATCC), whichcan produce New Delhi metallo-β-lactamase1(NDM-1) in the process of growth andreproduction. In this study, a novel bacteriophage was isolated from sewage byBAA-2146as the host strain. After purification, the plaque of Bacteriophage wasconsistent in size and shape. The bacteriophage was named as NKP-1. The phageformed clear negative colony in the early stage when cultured with the host strain.Several hours later, the plaques became larger and were surrounded by a large halo. The primary biological characteristics of the NKP-1has been studied. The optimumgrowth temperature of NKP-1was37℃, and the optimum pH value was7. NKP-1was resistant to chloroform and ether. When the MOI was0.1, the phage titer washighest, reaching7.5×10~9pfu/ml. The one step growth curve of NKP-1wasdetermined, the curve showed a short latency period of about30min and a rise periodof45min, and the burst size was95pfu/cell. Host spectrum analysis showed that theNKP-1has very narrow spectrum, only lysing a small amount of Klebsiellapneumoniae. The result of TEM showed that NKP-1has an isometrically hexagonalhead of65±5nm in diameter and a very short tail. Based on a number ofmorphological features, this phage should be a member of the Podoviridae family,order Claudovirales. Phage lysing experiments showed that NKP-1was lyticbacteriophage, which had the high efficiency of multiplication. The experiments invitro showed that NKP-1can quickly infect and lyse the Klebsiella pneumoniaestrains BAA-2146. Bacteremic mice infected by lethal dose of BAA-2146(4×10~9cfu/ml) were protected effectively by intraperitoneal administration of a single dose ofNKP-1(2×10~7pfu/ml).This is the first separation and research for the phage of New Delhimetallo-β-lactamase1(NDM-1) producing strains, which conducts helpfulexploration to use phage treatment of multiple drug-resistant bacteria infection. Thisstudy promotes the development of the application of bacteriophage to the treatmentof bacterial diseases. |
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