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      1. Author :
        Kadurugamuwa, J. L.; Sin, L.; Albert, E.; Yu, J.; Francis, K.; DeBoer, M.; Rubin, M.; Bellinger-Kawahara, C.; Jr, T. R. Parr; Contag, P. R.
      2. Title :
      3. Type :
        Journal Article
      4. Year :
        2003
      5. Publication :
        Infection and Immunity
      6. Products :
      7. Volume :
        71
      8. Issue :
        N/A
      9. Page Numbers :
        N/A
      10. Research Area :
        N/A
      11. Keywords :
        Animals, Bioware, Xen29, Xen5, Biofilms/ growth & development, Catheterization, Central Venous/adverse effects, Chemiluminescent Measurements, Colony Count, Microbial, Disease Models, Animal, Female, Humans, Luciferases/genetics/metabolism, Mice, Mice, Inbred BALB C, Pseudomonas Infections/ microbiology, Pseudomonas aeruginosa/genetics/ growth & development, Staphylococcal Infections/ microbiology, Staphylococcus aureus/genetics/ growth & development IVIS, Xenogen
      12. Abstract :
        We have developed a rapid, continuous method for real-time monitoring of biofilms, both in vitro and in a mouse infection model, through noninvasive imaging of bioluminescent bacteria colonized on Teflon catheters. Two important biofilm-forming bacterial pathogens, Staphylococcus aureus and Pseudomonas aeruginosa, were made bioluminescent by insertion of a complete lux operon. These bacteria produced significant bioluminescent signals for both in vitro studies and the development of an in vivo model, allowing effective real-time assessment of the physiological state of the biofilms. In vitro viable counts and light output were parallel and highly correlated (S. aureus r = 0.98; P. aeruginosa r = 0.99) and could be maintained for 10 days or longer, provided that growth medium was replenished every 12 h. In the murine model, subcutaneous implantation of the catheters (precolonized or postimplant infected) was well tolerated. An infecting dose of 10 (3) to 10 (5) CFU/catheter for S. aureus and P. aeruginosa resulted in a reproducible, localized infection surrounding the catheter that persisted until the termination of the experiment on day 20. Recovery of the bacteria from the catheters of infected animals showed that the bioluminescent signal corresponded to the CFU and that the lux constructs were highly stable even after many days in vivo. Since the metabolic activity of viable cells could be detected directly on the support matrix, nondestructively, and noninvasively, this method is especially appealing for the study of chronic biofilm infections and drug efficacy studies in vivo.
      13. URL :
        http://www.ncbi.nlm.nih.gov/pubmed/12540570
      14. Call Number :
        139339
      15. Serial :
        5926
      1. Author :
        Engelsman, A. F.; Mei, H. C. van der; Francis, K. P.; Busscher, H. J.; Ploeg, R. J.; Dam, G. M. van
      2. Title :
      3. Type :
        Journal Article
      4. Year :
        2009
      5. Publication :
        J Biomed Mater Res B Appl Biomater
      6. Products :
      7. Volume :
        88
      8. Issue :
        N/A
      9. Page Numbers :
        N/A
      10. Research Area :
        N/A
      11. Keywords :
        Bioware; IVIS, Xenogen; Xen29
      12. Abstract :
        Infection is the main cause of biomaterials-related failure. A simple technique to test in-vivo new antimicrobial and/or nonadhesive implant coatings is unavailable. Current in vitro methods for studying bacterial adhesion and growth on biomaterial surfaces lack the influence of the host immune system. Most in vivo methods to study biomaterials-related infections routinely involve implant-removal, preventing comprehensive longitudinal monitoring. In vivo imaging circumvents these drawbacks and is based on the use of noninvasive optical imaging of bioluminescent bacteria. Staphylococcus aureus Xen29 is genetically modified to be stably bioluminescent, by the introduction of a modified full lux operon onto its chromosome. Surgical meshes with adhering S. aureus Xen29 were implanted in mice and bacterial growth and spread into the surrounding tissue was monitored longitudinally from bioluminescence with a highly sensitive CCD camera. Distinct spatiotemporal bioluminescence patterns, extending beyond the mesh area into surrounding tissues were observed. After 10 days, the number of living organisms isolated from explanted meshes was found to correlate with bioluminescence prior to sacrifice of the animals. Therefore, it is concluded that in vivo imaging using bioluminescent bacteria is ideally suited to study antimicrobial coatings taking into account the host immune system. In addition, longitudinal monitoring of infection in one animal will significantly reduce the number of experiments and animals.
      13. URL :
        http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=18618733
      14. Call Number :
        137698
      15. Serial :
        7462
      1. Author :
        Xiong, Y. Q.; Willard, J.; Kadurugamuwa, J. L.; Yu, J.; Francis, K. P.; Bayer, A. S.
      2. Title :
      3. Type :
        Journal Article
      4. Year :
        2005
      5. Publication :
        Antimicrobial Agents and Chemotherapy
      6. Products :
      7. Volume :
        49
      8. Issue :
        N/A
      9. Page Numbers :
        N/A
      10. Research Area :
        N/A
      11. Keywords :
        IVIS, Xenogen; Bioware; Xen29
      12. Abstract :
        Therapeutic options for invasive Staphylococcus aureus infections have become limited due to rising antimicrobial resistance, making relevant animal model testing of new candidate agents more crucial than ever. In the present studies, a rat model of aortic infective endocarditis (IE) caused by a bioluminescently engineered, biofilm-positive S. aureus strain was used to evaluate real-time antibiotic efficacy directly. This strain was vancomycin and cefazolin susceptible but gentamicin resistant. Bioluminescence was detected and quantified daily in antibiotic-treated and control animals with IE, using a highly sensitive in vivo imaging system (IVIS). Persistent and increasing cardiac bioluminescent signals (BLS) were observed in untreated animals. Three days of vancomycin therapy caused significant reductions in both cardiac BLS (>10-fold versus control) and S. aureus densities in cardiac vegetations (P < 0.005 versus control). However, 3 days after discontinuation of vancomycin therapy, a greater than threefold increase in cardiac BLS was observed, indicating relapsing IE (which was confirmed by quantitative culture). Cefazolin resulted in modest decreases in cardiac BLS and bacterial densities. These microbiologic and cardiac BLS differences during therapy correlated with a longer time-above-MIC for vancomycin (>12 h) than for cefazolin (?4 h). Gentamicin caused neither a reduction in cardiac S. aureus densities nor a reduction in BLS. There were significant correlations between cardiac BLS and S. aureus densities in vegetations in all treatment groups. These data suggest that bioluminescent imaging provides a substantial advance in the real-time monitoring of the efficacy of therapy of invasive S. aureus infections in live animals.
      13. URL :
        http://www.ncbi.nlm.nih.gov/pubmed/15743898
      14. Call Number :
        144577
      15. Serial :
        7474
      1. Author :
        Kadurugamuwa, J. L.; Sin, L. V.; Yu, J.; Francis, K. P.; Kimura, R.; Purchio, T.; Contag, P. R.
      2. Title :
      3. Type :
        Journal Article
      4. Year :
        2003
      5. Publication :
        Antimicrobial Agents and Chemotherapy
      6. Products :
      7. Volume :
        47
      8. Issue :
        N/A
      9. Page Numbers :
        N/A
      10. Research Area :
        N/A
      11. Keywords :
        Animals, Anti-Bacterial Agents/ pharmacology, Bacterial Infections/drug therapy/microbiology, Biofilms/ drug effects/growth & development, Bioware; Catheterization/adverse effects, Chemiluminescent Measurements, Ciprofloxacin/pharmacology, Colony Count, Microbial, Disease Models, Animal, Dose-Response Relationship, Drug, Drug Monitoring/methods, Mice, Rifampin/pharmacology, Staphylococcus aureus/drug effects/genetics/growth & development, Tobramycin/pharmacology IVIS, Xenogen; Xen29
      12. Abstract :
        We have developed a rapid, continuous method for monitoring the effectiveness of several antibacterial agents in real time, noninvasively, by using a recently described mouse model of chronic biofilm infection (J. L. Kadurugamuwa et al., Infect. Immun. 71:882-890, 2003), which relies on biophotonic imaging of bioluminescent bacteria. To facilitate real-time monitoring of infection, we used a Staphylococcus aureus isolate that was made bioluminescent by inserting a modified lux operon into the bacterial chromosome. This bioluminescent reporter bacterium was used to study the antimicrobial effects of several antibiotics belonging to different molecular families. Treatment with rifampin, tobramycin, and ciprofloxacin was started 7 days after subcutaneous implantation of catheters precolonized with 10(4) CFU of S. aureus. Three different doses of antibiotics were administered twice a day for 4 consecutive days. The number of metabolically active bacteria in untreated mice and the tobramycin- and ciprofloxacin-treated groups remained relatively unchanged over the 4-week observation period, indicating poor efficacies for tobramycin and ciprofloxacin. A rapid dose-dependent decline in metabolic activity in rifampin-treated groups was observed, with almost a 90% reduction after two doses and nearly undetectable levels after three doses. The disappearance of light emission correlated with colony counts. After the final treatment, cell numbers rebounded as a function of concentration in a time-dependent manner. The staphylococci isolated from the catheters of mice treated with rifampin were uniformly resistant to rifampin but retained their in vitro susceptibilities to tobramycin and ciprofloxacin. Since the metabolic activities of viable cells and a postantibiotic effect could be detected directly on the support matrix nondestructively and noninvasively, the methodology is specifically appealing for investigating the effects of antibiotics on biofilms in vivo. Moreover, our study points to the possible use of biophotonic imaging for the detection of the development of resistance to therapeutic agents during treatment of chronic infections in vivo.
      13. URL :
        http://www.ncbi.nlm.nih.gov/pubmed/14506020
      14. Call Number :
        139345
      15. Serial :
        7448
      1. Author :
        Sottnik, J. L.; U, L. W.'Ren; Thamm, D. H.; Withrow, S. J.; Dow, S. W.
      2. Title :
      3. Type :
        Journal Article
      4. Year :
        2010
      5. Publication :
        Cancer Immunol Immunother
      6. Products :
      7. Volume :
        59
      8. Issue :
        N/A
      9. Page Numbers :
        N/A
      10. Research Area :
        N/A
      11. Keywords :
        Animals, Chronic Disease, Disease Models, Animal, Immunity, Innate, Killer Cells, Natural/immunology, Macrophages/immunology, Mice, Mice, Inbred C3H, Mice, Inbred Strains, Monocytes/immunology, Neoplasms, Neovascularization, Pathologic, Osteomyelitis/*complications, Osteosarcoma/*complications/*immunology/pathology, Staphylococcal Infections/*complications IVIS, Xenogen, Xen36
      12. Abstract :
        Clinical studies over the past several years have reported that metastasis-free survival times in humans and dogs with osteosarcoma are significantly increased in patients that develop chronic bacterial osteomyelitis at their surgical site. However, the immunological mechanism by which osteomyelitis may suppress tumor growth has not been investigated. Therefore, we used a mouse model of osteomyelitis to assess the effects of bone infection on innate immunity and tumor growth. A chronic Staphylococcal osteomyelitis model was established in C3H mice and the effects of infection on tumor growth of syngeneic DLM8 osteosarcoma were assessed. The effects of infection on tumor angiogenesis and innate immunity, including NK cell and monocyte responses, were assessed. We found that osteomyelitis significantly inhibited the growth of tumors in mice, and that the effect was independent of the infecting bacterial type, tumor type, or mouse strain. Depletion of NK cells or monocytes reversed the antitumor activity elicited by infection. Moreover, infected mice had a significant increase in circulating monocytes and numbers of tumor associated macrophages. Infection suppressed tumor angiogenesis but did not affect the numbers of circulating endothelial cells. Therefore, we concluded that chronic localized bacterial infection could elicit significant systemic antitumor activity dependent on NK cells and macrophages.
      13. URL :
        http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=19701748
      14. Call Number :
        143227
      15. Serial :
        5718
      1. Author :
        Pozo, J. L. del; Rouse, M. S.; Mandrekar, J. N.; Sampedro, M. F.; Steckelberg, J. M.; Patel, R.
      2. Title :
      3. Type :
        Journal Article
      4. Year :
        2009
      5. Publication :
        Antimicrobial Agents and Chemotherapy
      6. Products :
      7. Volume :
        53
      8. Issue :
        N/A
      9. Page Numbers :
        N/A
      10. Research Area :
        N/A
      11. Keywords :
        IVIS, Xenogen, Xen30, Xen5, Xen41
      12. Abstract :
        Bacterial biofilms are resistant to conventional antimicrobial agents. Prior in vitro studies have shown that electrical current (EC) enhances the activities of aminoglycosides, quinolones, and oxytetracycline against Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus epidermidis, Escherichia coli, and Streptococcus gordonii. This phenomenon, known as the bioelectric effect, has been only partially defined. The purpose of this work was to study the in vitro bioelectric effect on the activities of 11 antimicrobial agents representing a variety of different classes against P. aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA), and S. epidermidis. An eight-channel current generator/controller and eight chambers delivering a continuous flow of fresh medium with or without antimicrobial agents and/or EC to biofilm-coated coupons were used. No significant decreases in the numbers of log10 CFU/cm2 were seen after exposure to antimicrobial agents alone, with the exception of a 4.57-log-unit reduction for S. epidermidis and trimethoprim-sulfamethoxazole. We detected a statistically significant bioelectric effect when vancomycin plus 2,000 microamperes EC were used against MRSA biofilms (P = 0.04) and when daptomycin and erythromycin were used in combination with 200 or 2,000 microamperes EC against S. epidermidis biofilms (P = 0.02 and 0.0004, respectively). The results of these experiments indicate that the enhancement of the activity of antimicrobial agents against biofilm organisms by EC is not a generalizable phenomenon across microorganisms and antimicrobial agents.
      13. URL :
        http://www.ncbi.nlm.nih.gov/pubmed/18725436
      14. Call Number :
        137347
      15. Serial :
        5991
      1. Author :
        Pozo, J. L. del; Rouse, M. S.; Mandrekar, J. N.; Steckelberg, J. M.; Patel, R.
      2. Title :
      3. Type :
        Journal Article
      4. Year :
        2009
      5. Publication :
        Antimicrob Agents Chemother
      6. Products :
      7. Volume :
        53
      8. Issue :
        N/A
      9. Page Numbers :
        N/A
      10. Research Area :
        N/A
      11. Keywords :
        Aza Compounds/pharmacology, Biofilms/drug effects/*growth & development, Electricity/*adverse effects, Pseudomonas/drug effects/*growth & development, Quinolines/pharmacology, Staphylococcus/drug effects/*growth & development, Tobramycin/pharmacology IVIS, Xenogen, Xen30
      12. Abstract :
        The activity of electrical current against planktonic bacteria has previously been demonstrated. The short-term exposure of the bacteria in biofilms to electrical current in the absence of antimicrobials has been shown to have no substantial effect; however, longer-term exposure has not been studied. A previously described in vitro model was used to determine the effect of prolonged exposure (i.e., up to 7 days) to low-intensity (i.e., 20-, 200-, and 2,000-microampere) electrical direct currents on Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis biofilms. Dose- and time-dependent killing was observed. A maximum of a 6-log(10)-CFU/cm(2) reduction was observed when S. epidermidis biofilms were exposed to 2,000 microamperes for at least 2 days. A 4- to 5-log(10)-CFU/cm(2) reduction was observed when S. aureus biofilms were exposed to 2,000 microamperes for at least 2 days. Finally, a 3.5- to 5-log(10)-CFU/cm(2) reduction was observed when P. aeruginosa biofilms were exposed to electrical current for 7 days. A higher electrical current intensity correlated with greater decreases in viable bacteria at all time points studied. In conclusion, low-intensity electrical current substantially reduced the numbers of viable bacteria in staphylococcal or Pseudomonas biofilms, a phenomenon we have labeled the “electricidal effect.”
      13. URL :
        http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=18955534
      14. Call Number :
        137350
      15. Serial :
        7845
      1. Author :
        Dai, T.; Tegos, G. P.; Burkatovskaya, M.; Castano, A. P.; Hamblin, M. R.
      2. Title :
      3. Type :
        Journal Article
      4. Year :
        2009
      5. Publication :
        Antimicrobial Agents and Chemotherapy
      6. Products :
      7. Volume :
        53
      8. Issue :
        N/A
      9. Page Numbers :
        N/A
      10. Research Area :
        N/A
      11. Keywords :
        IVIS, Xenogen, Xen5, Xen44
      12. Abstract :
        An engineered chitosan acetate bandage preparation (HemCon) is used as a hemostatic dressing, and its chemical structure suggests that it should also be antimicrobial. We previously showed that when a chitosan acetate bandage was applied to full-thickness excisional wounds in mice that had been infected with pathogenic bioluminescent bacteria (Pseudomonas aeruginosa, Proteus mirabilis, and Staphylococcus aureus), it was able to rapidly kill the bacteria and save the mice from developing fatal infections. Wound healing was also stimulated. In the present study, we asked whether a chitosan acetate bandage could act as a topical antimicrobial dressing when it was applied to third-degree burns in mice contaminated with two of these bacterial species (P. aeruginosa and P. mirabilis). Preliminary experiments established the length of burn time and the number of bacteria needed to produce fatal infections in untreated mice and established that the chitosan acetate bandage could adhere to the infected burn for up to 21 days. In the case of P. aeruginosa infections, the survival rate of mice treated with the chitosan acetate bandage was 73.3% (whereas the survival rate of mice treated with a nanocrystalline silver dressing was 27.3% [P = 0.0055] and that of untreated mice was 13.3% [P < 0.0002]). For P. mirabilis infections, the comparable survival rates were 66.7%, 62.5%, and 23.1% respectively. Quantitative bioluminescent signals showed that the chitosan acetate bandage effectively controlled the growth of bacteria in the burn and prevented the development of systemic sepsis, as shown by blood culture. These data suggest that chitosan acetate bandage is efficacious in preventing fatal burn infections.
      13. URL :
        http://www.ncbi.nlm.nih.gov/pubmed/19015341
      14. Call Number :
        137209
      15. Serial :
        5713
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