Journal Article

IVIS, Xen29, Xen 29, Staphylococcus aureus Xen29, Acetates; Animals; *Biofilms; Bioprosthesis; Blood Vessel Prosthesis/*microbiology; Cattle; Colony Count, Microbial; Luminescent Measurements/*methods; Mice; Microbial Viability; Pericardium; *Photons; Polyesters; Polytetrafluoroethylene; Prospective Studies; Prosthesis-Related Infections/*diagnosis; Random Allocation; Silver Compounds; Staphylococcus aureus/isolation & purification/*physiology

OBJECTIVES: Biophotonic imaging was compared to standard enumeration method both for counting Staphylococcus aureus in biofilm and bacterial susceptibility tests of different graft materials. DESIGN: Prospective, randomized, controlled animal study. MATERIAL AND METHODS: Five types of vascular grafts were placed subcutaneously in 35 mice and challenged with bioluminescent S. aureus. The mice were divided into equal groups as follows: group A (polyester), group B (polytetrafluoroethylene), group C and D (two types of silver acetate-coated polyester) and group E (bovine pericardium). Controls were given only the bacteria. The bioluminescence signal of S. aureus, able to predict number of viable bacteria in biofilm without any manipulation, was measured at different time points. Five days postinfection, regular cultures of adherent bacteria on grafts were obtained. Comparative analyses between bioluminescence activity and culture enumeration were performed. RESULTS: The number of viable bacteria on silver-coated prostheses was the slightest, indicating superior bacterial resistance. The density of bacteria on polytetrafluoroethylene and polyester was comparable, with a non-significant advantage for polytetrafluoroethylene. Moreover, bioluminescence detected the number of viable S. aureus in biofilm more exactly compared to enumeration of bacteria. CONCLUSION: Bioluminescence imaging can be considered a useful tool to characterize susceptibility of any graft material to bacterial biofilm prior to implantation.

Journal Article

Xen31, Xen 31, MRSA, S. aureus, IVIS, Bioluminescence, Animals; Bacterial Infections/*drug therapy; Burns/drug therapy/microbiology; Candida/drug effects; Cations; Gram-Negative Bacteria/drug effects; Gram-Positive Bacteria/drug effects; Male; Methicillin-Resistant Staphylococcus aureus; Mice; Mice, Inbred BALB C; *Photochemotherapy; Photosensitizing Agents/*chemical synthesis/chemistry/pharmacology; Porphyrins/*chemical synthesis/chemistry/pharmacology; Solubility; Staphylococcal Infections/drug therapy/microbiology; Structure-Activity Relationship

Structures of typical photosensitizers used in antimicrobial photodynamic therapy are based on porphyrins, phthalocyanines, and phenothiazinium salts, with cationic charges at physiological pH values. However, derivatives of the porphycene macrocycle (a structural isomer of porphyrin) have barely been investigated as antimicrobial agents. Therefore, we report the synthesis of the first tricationic water-soluble porphycene and its basic photochemical properties. We successfully tested it for in vitro photoinactivation of different Gram-positive and Gram-negative bacteria, as well as a fungal species (Candida) in a drug-dose and light-dose dependent manner. We also used the cationic porphycene in vivo to treat an infection model comprising mouse third degree burns infected with a bioluminescent methicillin-resistant Staphylococcus aureus strain. There was a 2.6-log(10) reduction (p < 0.001) of the bacterial bioluminescence for the PDT-treated group after irradiation with 180 J.cm(-2) of red light.

Journal Article

IVIS, Xen29, Xen 29, Staphylococcus aureus Xen29, Animals; Anti-Bacterial Agents/*therapeutic use; Arthroplasty/*adverse effects; Disease Models, Animal; Humans; Joint Diseases/drug therapy/*microbiology/surgery; Joints/microbiology/surgery; Male; Mice; Mice, Inbred C57BL; Minocycline/therapeutic use; Postoperative Complications/drug therapy/microbiology/*prevention &; control; Prostheses and Implants; Rifampin/therapeutic use; Staphylococcal Infections/drug therapy/microbiology/*prevention &; control/surgery; Staphylococcus aureus/drug effects/genetics/*physiology

BACKGROUND: Post-arthroplasty infections represent a devastating complication of total joint replacement surgery, resulting in multiple reoperations, prolonged antibiotic use, extended disability and worse clinical outcomes. As the number of arthroplasties in the U.S. will exceed 3.8 million surgeries per year by 2030, the number of post-arthroplasty infections is projected to increase to over 266,000 infections annually. The treatment of these infections will exhaust healthcare resources and dramatically increase medical costs. METHODOLOGY/PRINCIPAL FINDINGS: To evaluate novel preventative therapeutic strategies against post-arthroplasty infections, a mouse model was developed in which a bioluminescent Staphylococcus aureus strain was inoculated into a knee joint containing an orthopaedic implant and advanced in vivo imaging was used to measure the bacterial burden in real-time. Mice inoculated with 5x10(3) and 5x10(4) CFUs developed increased bacterial counts with marked swelling of the affected leg, consistent with an acute joint infection. In contrast, mice inoculated with 5x10(2) CFUs developed a low-grade infection, resembling a more chronic infection. Ex vivo bacterial counts highly correlated with in vivo bioluminescence signals and EGFP-neutrophil fluorescence of LysEGFP mice was used to measure the infection-induced inflammation. Furthermore, biofilm formation on the implants was visualized at 7 and 14 postoperative days by variable-pressure scanning electron microscopy (VP-SEM). Using this model, a minocycline/rifampin-impregnated bioresorbable polymer implant coating was effective in reducing the infection, decreasing inflammation and preventing biofilm formation. CONCLUSIONS/SIGNIFICANCE: Taken together, this mouse model may represent an alternative pre-clinical screening tool to evaluate novel in vivo therapeutic strategies before studies in larger animals and in human subjects. Furthermore, the antibiotic-polymer implant coating evaluated in this study was clinically effective, suggesting the potential for this strategy as a therapeutic intervention to combat post-arthroplasty infections.

Journal Article

ProSense, IVIS, Animals; Breast Neoplasms/pathology/*surgery; Cell Line, Tumor; Disease Models, Animal; Female; *Microscopy, Fluorescence; Rats; *Surgery, Computer-Assisted; Transplantation, Isogeneic; Xenograft Model Antitumor Assays

Tumor involvement of resection margins is found in a large proportion of patients who undergo breast-conserving surgery. Near-infrared (NIR) fluorescence imaging is an experimental technique to visualize cancer cells during surgery. To determine the accuracy of real-time NIR fluorescence imaging in obtaining tumor-free resection margins, a protease-activatable NIR fluorescence probe and an intraoperative camera system were used in the EMR86 orthotopic syngeneic breast cancer rat model. Influence of concentration, timing and number of tumor cells were tested in the MCR86 rat breast cancer cell line. These variables were significantly associated with NIR fluorescence probe activation. Dosing and tumor size were also significantly associated with fluorescence intensity in the EMR86 rat model, whereas time of imaging was not. Real-time NIR fluorescence guidance of tumor resection resulted in a complete resection of 17 out of 17 tumors with minimal excision of normal healthy tissue (mean minimum and a mean maximum tumor-free margin of 0.2 +/- 0.2 mm and 1.3 +/- 0.6 mm, respectively). Moreover, the technique enabled identification of remnant tumor tissue in the surgical cavity. Histological analysis revealed that the NIR fluorescence signal was highest at the invasive tumor border and in the stromal compartment of the tumor. In conclusion, NIR fluorescence detection of breast tumor margins was successful in a rat model. This study suggests that clinical introduction of intraoperative NIR fluorescence imaging has the potential to increase the number of complete tumor resections in breast cancer patients undergoing breast-conserving surgery.

Journal Article

OsteoSense, Animals; Bone Neoplasms/radionuclide imaging/*secondary; Diagnostic Imaging/*methods; Forecasting; Optics and Photonics/*trends; Positron-Emission Tomography/methods; Tomography, Emission-Computed, Single-Photon/methods; X-Ray Microtomography/methods; X-Rays

Optical Imaging has evolved into one of the standard molecular imaging modalities used in pre-clinical cancer research. Bone research however, strongly depends on other imaging modalities such as SPECT, PET, x-ray and muCT. Each imaging modality has its own specific strengths and weaknesses concerning spatial resolution, sensitivity and the possibility to quantify the signal. An increasing number of bone specific optical imaging models and probes have been developed over the past years. This review gives an overview of optical imaging modalities, models and probes that can be used to study skeletal complications of cancer in small laboratory animals.