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      1. Author :
        Yu, Jun; Wu, Jenny; Francis, Kevin P; Purchio, Tony F; Kadurugamuwa, Jagath L
      2. Title :
      3. Type :
        Journal Article
      4. Year :
        2005
      5. Publication :
        The Journal of antimicrobial chemotherapy
      6. Products :
      7. Volume :
        55
      8. Issue :
        4
      9. Page Numbers :
        N/A
      10. Research Area :
        N/A
      11. Keywords :
        Animals; Anti-Bacterial Agents; Biofilms; Bioware; Drug Resistance, Bacterial; Mice; Mutation; Rifampin; Staphylococcus aureus; Xen29
      12. Abstract :
        OBJECTIVES To investigate in vivo fitness of rifampicin-resistant Staphylococcus aureus mutants in a mouse biofilm model using bioluminescence imaging. MATERIALS AND METHODS S. aureus was engineered with a luciferase operon to emit bioluminescence that can be detected in vivo using an IVIS imaging system. Two rifampicin-resistant strains of S. aureus that were previously isolated from animals undergoing rifampicin treatment, S464P (resistant to low concentrations of rifampicin) and H481Y (resistant to high concentrations of rifampicin), were characterized and then compared with their parental strain for in vivo fitness to form biofilm infections in the absence of rifampicin. RESULTS The mutant S464P showed better adaptation to in vivo growth than either the parental strain or H481Y without selective pressure. Six days after implanting pre-colonized catheters, bioluminescent signals were seen from 100% of the catheters coated by the mutant S464P. In comparison, only 83% and 61% of the catheters coated by the parental strain and H481Y, respectively, maintained a signal in vivo. Rifampicin treatment of S464P biofilms in vivo resulted in a slight decline, but earlier rebound in bioluminescence from these catheters compared with the parental signal, whereas rifampicin had no affect on bioluminescence in mice infected with mutant H481Y. CONCLUSIONS The mutant with low-level rifampicin resistance appears to be better adapted to in vivo growth than the mutant that has high-level rifampicin resistance. Moreover, the former mutant may actually have a slight competitive advantage over the rifampicin-susceptible strain (parental), raising awareness for the occurrence of such strains in clinical environments.
      13. URL :
        http://www.ncbi.nlm.nih.gov/pubmed/15743898
      14. Call Number :
        PKI @ catherine.lautenschlager @
      15. Serial :
        9055
      1. Author :
        Bisland, Stuart K; Chien, Claudia; Wilson, Brian C; Burch, Shane
      2. Title :
      3. Type :
        Journal Article
      4. Year :
        2006
      5. Publication :
        Photochemical & photobiological sciences: Official journal of the European Photochemistry Association and the European Society for Photobiology
      6. Products :
      7. Volume :
        5
      8. Issue :
        1
      9. Page Numbers :
        N/A
      10. Research Area :
        N/A
      11. Keywords :
        Aminolevulinic Acid; Animals; Biofilms; Bioware; Cell Survival; Disease Models, Animal; Drug Evaluation, Preclinical; Female; Implants, Experimental; Light; Luminescent Measurements; Methylene Blue; Osteomyelitis; Photochemotherapy; Photosensitizing Agents; Rats; Rats, Sprague-Dawley; Staphylococcus aureus; Xen29
      12. Abstract :
        Osteomyelitis can lead to severe morbidity and even death resulting from an acute or chronic inflammation of the bone and contiguous structures due to fungal or bacterial infection. Incidence approximates 1 in 1000 neonates and 1 in 5000 children in the United States annually and increases up to 0.36% and 16% in adults with diabetes or sickle cell anaemia, respectively. Current regimens of treatment include antibiotics and/or surgery. However, the increasing number of antibiotic resistant pathogens suggests that alternate strategies are required. We are investigating photodynamic therapy (PDT) as one such alternate treatment for osteomyelitis using a bioluminescent strain of biofilm-producing staphylococcus aureus (S. aureus) grown onto kirschner wires (K-wire). S. aureus-coated K-wires were exposed to methylene blue (MB) or 5-aminolevulinic acid (ALA)-mediated PDT either in vitro or following implant into the tibial medullary cavity of Sprague-Dawley rats. The progression of S. aureus biofilm was monitored non-invasively using bioluminescence and expressed as a percentage of the signal for each sample immediately prior to treatment. S. aureus infections were subject to PDT 10 days post inoculation. Treatment comprised administration of ALA (300 mg kg(-1)) intraperitoneally followed 4 h later by light (635 +/- 10 nm; 75 J cm(-2)) delivered transcutaneously via an optical fiber placed onto the tibia and resulted in significant delay in bacterial growth. In vitro, MB and ALA displayed similar cell kill with > or =4 log(10) cell kill. In vivo, ALA-mediated PDT inhibited biofilm implants in bone. These results confirm that MB or ALA-mediated PDT have potential to treat S. aureus cultures grown in vitro or in vivo using an animal model of osteomyelitis.
      13. URL :
        http://www.ncbi.nlm.nih.gov/pubmed/16395425
      14. Call Number :
        PKI @ catherine.lautenschlager @
      15. Serial :
        9054
      1. Author :
        Baddour, Ralph E; Dadani, Farhan N; Kolios, Michael C; Bisland, Stuart K
      2. Title :
      3. Type :
        Journal Article
      4. Year :
        2007
      5. Publication :
        Journal of biological physics
      6. Products :
      7. Volume :
        33
      8. Issue :
        1
      9. Page Numbers :
        N/A
      10. Research Area :
        N/A
      11. Keywords :
        Bioware; Xen29
      12. Abstract :
        Ultrasound imaging is proving to be an important tool for medical diagnosis of dermatological disease. Backscatter spectral profiles using high-frequency ultrasound (HFUS, 10-100 MHz) are sensitive to subtle changes in eukaryotic cellular morphology and mechanical properties that are indicative of early apoptosis, the main type of cell death induced following photodynamic therapy (PDT). We performed experiments to study whether HFUS could also be used to discern changes in bacteria following PDT treatment. Pellets of planktonic Staphylococcus aureus were treated with different PDT protocols and subsequently interrogated with HFUS. Changes in ultrasound backscatter response were found to correlate with antimicrobial effect. Despite their small size, distinct changes in bacterial morphology that are indicative of cell damage or death are detectable by altered backscatter spectra from bacterial ensembles using HFUS. This highlights the potential for HFUS in rapidly and non-invasively assessing the structural changes related to antimicrobial response.
      13. URL :
        http://www.ncbi.nlm.nih.gov/pubmed/19669553
      14. Call Number :
        PKI @ catherine.lautenschlager @
      15. Serial :
        9052
      1. Author :
        Mortin, Lawrence I; Li, Tongchuan; Van Praagh, Andrew D G; Zhang, Shuxin; Zhang, Xi-Xian; Alder, Jeff D
      2. Title :
      3. Type :
        Journal Article
      4. Year :
        2007
      5. Publication :
        Antimicrobial agents and chemotherapy
      6. Products :
      7. Volume :
        51
      8. Issue :
        5
      9. Page Numbers :
        N/A
      10. Research Area :
        N/A
      11. Keywords :
        Acetamides; Animals; Anti-Bacterial Agents; Bioware; Colony Count, Microbial; Daptomycin; Female; Luminescent Measurements; Methicillin Resistance; Mice; Microbial Sensitivity Tests; Neutropenia; Oxazolidinones; Peritonitis; Staphylococcus aureus; Xen29
      12. Abstract :
        The rising rates of antibiotic resistance accentuate the critical need for new antibiotics. Daptomycin is a new antibiotic with a unique mode of action and a rapid in vitro bactericidal effect against gram-positive organisms. This study examined the kinetics of daptomycin's bactericidal action against peritonitis caused by methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) in healthy and neutropenic mice and compared this activity with those of other commonly used antibiotics. CD-1 mice were inoculated intraperitoneally with lethal doses of MSSA (Xen-29) or MRSA (Xen-1), laboratory strains transformed with a plasmid containing the lux operon, which confers bioluminescence. One hour later, the animals were given a single dose of daptomycin at 50 mg/kg of body weight subcutaneously (s.c.), nafcillin at 100 mg/kg s.c., vancomycin at 100 mg/kg s.c., linezolid at 100 mg/kg via gavage (orally), or saline (10 ml/kg s.c.). The mice were anesthetized hourly, and photon emissions from living bioluminescent bacteria were imaged and quantified. The luminescence in saline-treated control mice either increased (neutropenic mice) or remained relatively unchanged (healthy mice). In contrast, by 2 to 3 h postdosing, daptomycin effected a 90% reduction of luminescence of MSSA or MRSA in both healthy and neutropenic mice. The activity of daptomycin against both MSSA and MRSA strains was superior to those of nafcillin, vancomycin, and linezolid. Against MSSA peritonitis, daptomycin showed greater and more rapid bactericidal activity than nafcillin or linezolid. Against MRSA peritonitis, daptomycin showed greater and more rapid bactericidal activity than vancomycin or linezolid. The rapid decrease in the luminescent signal in the daptomycin-treated neutropenic mice underscores the potency of this antibiotic against S. aureus in the immune-suppressed host.
      13. URL :
        http://www.ncbi.nlm.nih.gov/pubmed/17307984
      14. Call Number :
        PKI @ catherine.lautenschlager @
      15. Serial :
        9050
      1. Author :
        Ohlsen, Knut; Lorenz, Udo
      2. Title :
      3. Type :
        Journal Article
      4. Year :
        2007
      5. Publication :
        Future microbiology
      6. Products :
      7. Volume :
        2
      8. Issue :
        6
      9. Page Numbers :
        N/A
      10. Research Area :
        N/A
      11. Keywords :
        Anti-Bacterial Agents; Bioware; Community-Acquired Infections; Humans; Methicillin Resistance; Staphylococcal Infections; Staphylococcus aureus; Xen29
      12. Abstract :
        Multiple resistant staphylococci that cause significant morbidity and mortality are the leading cause of nosocomial infections. Meanwhile, methicillin-resistant Staphylococcus aureus (MRSA) also spreads in the community, where highly virulent strains infect children and young adults who have no predisposing risk factors. Although some treatment options remain, the search for new antibacterial targets and lead compounds is urgently required to ensure that staphylococcal infections can be effectively treated in the future. Promising targets for new antibacterials are gene products that are involved in essential cell functions. In addition to antibacterials, active and passive immunization strategies are being developed that target surface components of staphylococci such as cell wall-linked adhesins, teichoic acids and capsule or immunodominant antigens.
      13. URL :
        http://www.ncbi.nlm.nih.gov/pubmed/18041906
      14. Call Number :
        PKI @ catherine.lautenschlager @
      15. Serial :
        9049
      1. Author :
        Heit, Bryan; Robbins, Stephen M; Downey, Charlene M; Guan, Zhiwen; Colarusso, Pina; Miller, B Joan; Jirik, Frank R; Kubes, Paul
      2. Title :
      3. Type :
        Journal Article
      4. Year :
        2008
      5. Publication :
        Nature immunology
      6. Products :
      7. Volume :
        9
      8. Issue :
        7
      9. Page Numbers :
        N/A
      10. Research Area :
        N/A
      11. Keywords :
        Animals; Arthritis, Experimental; Bioware; Chemotaxis, Leukocyte; Humans; Inflammation; Mice; Mice, Transgenic; Neutrophils; p38 Mitogen-Activated Protein Kinases; Phosphatidylinositol 3-Kinases; Phosphatidylinositol Phosphates; Protein Transport; PTEN Phosphohydrolase; Xen29
      12. Abstract :
        Neutrophils encounter and 'prioritize' many chemoattractants in their pursuit of bacteria. Here we tested the possibility that the phosphatase PTEN is responsible for the prioritization of chemoattractants. Neutrophils induced chemotaxis by two separate pathways, the phosphatidylinositol-3-OH kinase (PI(3)K) phosphatase and tensin homolog (PTEN) pathway, and the p38 mitogen-activated protein kinase pathway, with the p38 pathway dominating over the PI(3)K pathway. Pten(-/-) neutrophils could not prioritize chemoattractants and were 'distracted' by chemokines when moving toward bacterial chemoattractants. In opposing gradients, PTEN became distributed throughout the cell circumference, which inhibited all PI(3)K activity, thus permitting 'preferential' migration toward bacterial products via phospholipase A(2) and p38. Such prioritization was defective in Pten(-/-) neutrophils, which resulted in defective bacterial clearance in vivo. Our data identify a PTEN-dependent mechanism in neutrophils to prioritize, 'triage' and integrate responses to multiple chemotactic cues.
      13. URL :
        http://www.ncbi.nlm.nih.gov/pubmed/18536720
      14. Call Number :
        PKI @ catherine.lautenschlager @
      15. Serial :
        9048
      1. Author :
        N/A
      2. Title :
      3. Type :
        Journal Article
      4. Year :
        2008
      5. Publication :
        Journal of orthopaedic research: official publication of the Orthopaedic Research Society
      6. Products :
      7. Volume :
        26
      8. Issue :
        1
      9. Page Numbers :
        N/A
      10. Research Area :
        N/A
      11. Keywords :
        Animals; Antibody Formation; Bacterial Proteins; Bioware; Disease Models, Animal; DNA, Bacterial; Endonucleases; Female; Mice; Mice, Inbred C57BL; Micrococcal Nuclease; Osteolysis; Osteomyelitis; Prosthesis-Related Infections; Reverse Transcriptase Polymerase Chain Reaction; Staphylococcal Infections; Staphylococcus aureus; Tibia; Xen29
      12. Abstract :
        Although osteomyelitis (OM) remains a serious problem in orthopedics, progress has been limited by the absence of an in vivo model that can quantify the bacterial load, metabolic activity of the bacteria over time, immunity, and osteolysis. To overcome these obstacles, we developed a murine model of implant-associated OM in which a stainless steel pin is coated with Staphylococcus aureus and implanted transcortically through the tibial metaphysis. X-ray and micro-CT demonstrated concomitant osteolysis and reactive bone formation, which was evident by day 7. Histology confirmed all the hallmarks of implant-associated OM, namely: osteolysis, sequestrum formation, and involucrum of Gram-positive bacteria inside a biofilm within necrotic bone. Serology revealed that mice mount a protective humoral response that commences with an IgM response after 1 week, and converts to a specific IgG2b response against specific S. aureus proteins by day 11 postinfection. Real-time quantitative PCR (RTQ-PCR) for the S. aureus specific nuc gene determined that the peak bacterial load occurs 11 days postinfection. This coincidence of decreasing bacterial load with the generation of specific antibodies is suggestive of protective humoral immunity. Longitudinal in vivo bioluminescent imaging (BLI) of luxA-E transformed S. aureus (Xen29) combined with nuc RTQ-PCR demonstrated the exponential growth phase of the bacteria immediately following infection that peaks on day 4, and is followed by the biofilm growth phase at a significantly lower metabolic rate (p < 0.05). Collectively, these studies demonstrate the first quantitative model of implant-associated OM that defines the kinetics of microbial growth, osteolysis, and humoral immunity following infection.
      13. URL :
        http://www.ncbi.nlm.nih.gov/pubmed/17676625
      14. Call Number :
        PKI @ catherine.lautenschlager @
      15. Serial :
        9047
      1. Author :
        N/A
      2. Title :
      3. Type :
        Journal Article
      4. Year :
        2008
      5. Publication :
        Microbes and infection / Institut Pasteur
      6. Products :
      7. Volume :
        10
      8. Issue :
        3
      9. Page Numbers :
        N/A
      10. Research Area :
        N/A
      11. Keywords :
        Animals; Bacterial Proteins; Biofilms; Bioware; Catheterization, Central Venous; Male; Mice; Point Mutation; Sigma Factor; Staphylococcal Infections; Staphylococcus aureus; Virulence; Xen29
      12. Abstract :
        The impact of the alternative sigma factor sigma B (SigB) on pathogenesis of Staphylococcus aureus is not conclusively clarified. In this study, a central venous catheter (CVC) related model of multiorgan infection was used to investigate the role of SigB for the pathogenesis of S. aureus infections and biofilm formation in vivo. Analysis of two SigB-positive wild-type strains and their isogenic mutants revealed uniformly that the wild-type was significantly more virulent than the SigB-deficient mutant. The observed difference in virulence was apparently not linked to the capability of the strains to form biofilms in vivo since wild-type and mutant strains were able to produce biofilm layers inside of the catheter. The data strongly indicate that the alternative sigma factor SigB plays a role in CVC-associated infections caused by S. aureus.
      13. URL :
        http://www.ncbi.nlm.nih.gov/pubmed/18328762
      14. Call Number :
        PKI @ catherine.lautenschlager @
      15. Serial :
        9046