Personal Fluid and Bacteria transplant {#Sec16} ------------------------------------ ### Prophylactic transplant of donor fluids {#Sec17} The use of donor transplants of fluids to prevent infection in an ICU patient is a well-established practice to protect the patient against bloodstream infections and ventilator-associated pneumonia. With the recent emergence of multi-drug resistant bacteria, including ESBL-producing bacteria and MRSA, the number of ESBL-positive patients has grown rapidly. Currently, ESBL-producing bacteria and MRSA are becoming important threats to public health as bacteria that cause opportunistic infections^[@CR48]^. With the lack of the development of alternative treatments or new antibiotics, use of antibiotic-containing donor fluids for prophylaxis against infection is a method that has the potential to treat a large number of patients. For example, transplants of blood for patients infected with *Acinetobacter baumannii*^[@CR19],[@CR20]^ have been shown to reduce the mortality rate in patients. Blood is an effective and useful donor fluid to prevent infection in patients with severe pneumonia due to *Acinetobacter baumannii*, which is resistant to several antibiotics including carbapenems, one of the most effective antibiotics against *Acinetobacter baumannii*^[@CR49]--[@CR52]^. Moreover, blood is a source of immune cells, cytokines, and immunoglobulins^[@CR51],[@CR52]^. These molecules are associated with disease severity, prognosis, and mortality^[@CR53],[@CR54]^. Because blood is a blood source that is easily available for treatment, the administration of donor fluid is also cost-effective, while it also protects the patient against infection. However, in patients who are infected with bacteria such as ESBL-positive *Klebsiella pneumoniae*, patients can exhibit resistance to ESBL bacteria within a day of treatment, as they already possess the antibiotic resistance genes for the bacteria^[@CR54]^. The combination of donor fluids and antibiotics has been shown to be effective for preventing bacterial infection and minimizing drug resistance in patients. In addition, several clinical trials have indicated that treatment of MDR bacteria using antibiotics in combination with donor fluids is associated with higher cure rates and higher survival rates^[@CR20],[@CR55]^. ### Transplant of bacterial cultures {#Sec18} Since the discovery of penicillin by Alexander Fleming, antibiotics have been considered to be the primary therapeutic agents for bacterial infection. However, bacterial resistance has become an urgent issue because of the overuse of antibiotics. Resistance among bacteria to existing antibiotics is becoming a major global public health issue, especially in developing countries^[@CR50],[@CR56]--[@CR59]^. Infections with resistant bacteria have a high mortality rate, and increase in infections due to MDR bacterial infections have resulted in a serious public health problem^[@CR49],[@CR50],[@CR59]--[@CR61]^. In the United States, the proportion of nosocomial infections caused by MDR bacteria increased from approximately 3% in 2000 to 5.7% in 2006^[@CR62],[@CR63]^. Even more alarming is that most bacteria have become resistant to existing antibiotics. It is predicted that, by 2050, 10 million deaths will occur due to antibiotic-resistant bacterial infections each year^[@CR49],[@CR50]^. Hence, the development of an alternative strategy is urgently needed to prevent MDR bacterial infections. Considering the difficulty of finding effective antibacterial agents, we need new solutions to the problem. The development of an effective antibacterial treatment requires knowledge of the types of antibiotics or antibiotics that can control the growth of the bacteria, or new methods for developing effective antibiotics. Moreover, the development of effective antibiotics requires the development of new research tools^[@CR59],[@CR64]--[@CR67]^. Bacterial infections can be transferred through medical staff, patients, and medical supplies, and the bacteria that cause these infections can be transmitted easily to patients due to changes in the air and environment in hospitals^[@CR54],[@CR68]^. A patient may be infected with bacteria during a medical procedure, including the insertion of an IV, insertion of a medical catheter, treatment, and surgery. In addition, patients in the hospital can be infected with bacteria through contact with medical staff^[@CR69]--[@CR71]^. To resolve the problem of antibiotic resistance, we need to isolate and identify the types of bacteria, and, most importantly, the type of antibiotic. However, it is difficult to identify whether and when an infection has occurred because of overlapping symptoms of infections in the clinical setting, including systemic infections and local infections. We have presented a novel solution to these problems. A study has indicated that many strains of bacteria produce biofilms, and biofilm production is increased after the administration of antibiotics^[@CR72]^. One of the major causes of antibiotic resistance is the expression of antibiotic resistance genes from the biofilm to defend bacteria against antibiotics^[@CR73]^. To prevent biofilm formation in patients, anti-biofilm drugs and strategies should be developed. We designed a study to prevent biofilm formation by coating anti-biofilm drugs on a catheter to protect against bacterial infection^[@CR74]^. The catheter used for the experiment, a medical device, was coated with biopolymers containing tannic acid, which controls biofilm formation. We succeeded in preventing biofilm formation by Gram-positive bacteria such as MRSA^[@CR74]^. However, the efficiency of antibiotic treatment is decreased by using tannic acid, a known anti-bacterial agent^[@CR75]^. Thus, we removed tannic acid from the biopolymers of the drug, and used silver nanoparticles (AgNPs), which are potent anti-bacterial agents, as a substitute for tannic acid^[@CR75],[@CR76]^. Silver nanoparticles are well-known to be excellent antimicrobial agents, and the anti-bacterial effects of silver nanoparticles are attributed to its large surface area to volume ratio and to the active surface sites that are in contact with and adsorb to the bacterial surface. AgNPs interact with proteins and lipids of bacteria and alter bacterial metabolism, metabolism, and respiration^[@CR75]--[@CR77]^. In addition, AgNPs can activate the transcription of antibacterial peptides, and can be used as antibacterial nanofilm coating in medical devices such as catheters and prosthetics^[@CR75],[@CR76]^. A recent study has shown that AgNPs do not interfere with the growth of human cells and, instead, provide superior anti-microbial effects against bacteria in both an *in vitro* and an *in vivo* model^[@CR78]^. Furthermore, silver nanoparticles have low cytotoxicity and do not interfere with platelet function. For the prevention of bacterial biofilm formation in patients, we can develop a catheter coated with a nano-antibacterial coating in order to reduce biofilm formation and to prevent infections in the internal organs of the body. The clinical study presented here is based on the same concept that we previously reported^[@CR74]^, and is the first report regarding the effects of a nano-antibacterial coating on a catheter to prevent biofilm formation and to prevent infection in a hospital setting. This study has proven that AgNPs coated on a catheter can decrease the bacteria burden in the skin of patients, and prevent the development of acute bacterial skin infections. The Nanoantibacterial concept can be applied to prevent bacterial infection of patients in various hospital settings. In addition, it can be used as a catheter coating for patients undergoing surgery to prevent the development of post-operative infections and catheter-related infections. In this study, we found that patients who were administered with AgNPs in the catheter to prevent bacterial biofilm formation were resistant to bacterial infection. For example, if a catheter was used for a patient with a central line for cancer therapy, the catheter must be removed immediately if the patient experiences symptoms of fever, such as a temperature over 38 °C, which is a general sign of infection and the result of an inflammation. To prevent patients from developing infections in this setting, a catheter must be used that contains AgNPs. To resolve the problem of antibiotic resistance due to the overuse of antibiotics, this study is expected to prevent the development of bacterial infections in patients by inserting catheters containing a Nanoantibacterial coating into the patient's blood vessels and by administering donor fluids containing antibiotics that are released from the catheter, along with antibiotic agents that are administrated orally to prevent the development of new drug resistance. Through this method, the patient can be protected against infections and the overuse of antibiotics. Moreover, medical staff can use the catheter to treat patients in the same hospital. **Publisher's note:** Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This research was supported by the KAIST Startup Research Program (N1115040) and by the Project of Translational & Clinical Research Core from KAIST (KHCT-C17092), Ministry of Science, ICT & Future Planning. Y.G. and H.C.L. designed the experiments. Y.G. and E.K. performed the experiments. J.K. and H.C.L. analysed the data and contributed reagents. Y.G. wrote the manuscript. J.K., Y.K. and H.C.L. reviewed and edited the manuscript. The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request. Competing Interests {#FPar1} =================== The authors declare no competing interests.