Near-Infrared Photothermal/Photodynamic-in-One Agents Integrated with a Guanidinium-Based Covalent Organic Framework for Intelligent Targeted Imaging-Guided Precision Chemo/PTT/PDT Sterilization.

Phototherapy holds great promise in the treatment of bacterial infections, especially the multidrug resistant bacterial infections. However, most therapeutic agents are based on the integration of individual photothermal agents and photosensitizers, always in the activated state, and generally lack bacterial specificity, resulting in uncertain pharmacokinetics and serious nonspecific damage to normal tissues. Herein, we report a pH-responsive nanoplatform with synergistic chemo-phototherapy function for smart fluorescence imaging-guided precision sterilization. pH reversible activated symmetric cyanine was designed and prepared as a bacterial-specific imaging unit and PTT/PDT-in-one agent. Meanwhile, a guanidinium-based covalent organic framework (COF) was employed as a nanocarrier and chemotherapy agent to build the intelligent nanoplatform via electrostatic self-assembly. The self-assembly of the PTT/PDT-in-one agent and the COF greatly improves the stability and blood circulation of the PTT/PDT-in-one agent and provides charge-reversed intelligent targeting ability. The developed smart nanoplatform not only enables bacterial-targeted imaging but also possesses chemo/PTT/PDT synergetic high-efficiency bactericidal effects with little side effects, showing great potential in practical applications.

Enzyme-responsive turn-on nanoprobes for in situ fluorescence imaging and localized photothermal treatment of multidrug-resistant bacterial infections.

Sensitive diagnosis and elimination of multidrug-resistant bacterial infections at an early stage remain paramount challenges. Herein, we present a gelatinase-responsive turn-on nanoprobe for in situ near-infrared (NIR) fluorescence imaging and localized photothermal treatment (PTT) of in vivo methicillin-resistant Staphylococcus aureus (MRSA) infections. The designed nanoprobe (named AuNS-Apt-Cy) is based on gold nanostars functionalized with MRSA-identifiable aptamer and gelatinase-responsive heptapeptide linker (CPLGVRG)-cypate complexes. The AuNS-Apt-Cy nanoprobe is non-fluorescent in aqueous environments due to the fluorescence resonance energy transfer between the gold nanostar core and cypate dye. We demonstrate that the AuNS-Apt-Cy nanoprobe can achieve MRSA targeting and accumulation as well as gelatinase (overexpressed in MRSA environments)-responsive turn-on NIR fluorescence due to the cleavage of the CPLGVRG linker and localized in vitro PTT via a mechanism involving bacterial cell wall and membrane disruption. In vivo experiments show that the AuNS-Apt-Cy nanoprobe can enable rapid (1 h post-administration) and in situ turn-on NIR fluorescence imaging with high sensitivity (105 colony-forming units) in diabetic wound and implanted bone plate mouse models. Remarkably, the AuNS-Apt-Cy nanoprobe can afford efficient localized PTT of diabetic wound and implanted bone plate-associated MRSA infections under the guidance of turn-on NIR fluorescence imaging, showing robust capability for early diagnosis and treatment of in vivo MRSA infections. In addition, the nanoprobe exhibits negligible damage to surrounding healthy tissues during PTT due to its targeted accumulation in the MRSA-infected site, guaranteeing its excellent in vivo biocompatibility and solving the main bottlenecks that hinder the clinical application of PTT-based antibacterial strategies.

Construction of biocompatible bovine serum albumin nanoparticles composed of nano graphene oxide and AIEgen for dual-mode phototherapy bacteriostatic and bacterial tracking.

BACKGROUND: Efficient and highly controllable antibacterial effect, as well as good biocompatibility are required for antibacterial materials to overcome multi-drug resistance in bacteria. Herein, nano graphene oxide (NGO)-based near-infrared (NIR) photothermal antibacterial materials was schemed to complex with biocompatible bovine serum albumin (BSA) and aggregation-induced emission fluorogen (AIEgen) with daylight-stimulated ROS-producing property for dual-mode phototherapy in the treatment of antibiotic resistance bacteria. RESULTS: Upon co-irradiation of daylight and NIR laser, NGO-BSA-AIE nanoparticles (NPs) showed superiorly antibacterial effect (more than 99%) both against amoxicillin (AMO)-resistant Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) by comparison with sing-model phototherapy. Meanwhile, the NGO-BSA-AIE NPs displayed prominent stability and excellently controllable biocompatibility. More importantly, under daylight irradiation, the AIEgen not only produced plentiful ROS for killing bacteria, but also presented fluorescence image for tracking bacteria. CONCLUSIONS: Hence, the designed system provided tempting strategy of employing light as impetus for tracking bacterial distribution and photothermal/photodynamic synergistic treatment of antibiotic resistance antibacterial.

A Gold/Silver Hybrid Nanoparticle for Treatment and Photoacoustic Imaging of Bacterial Infection.

Ag+ ions are a well-known antibacterial agent, and Ag nanoparticles act as a reservoir of these Ag+ ions for targeted therapy of bacterial infections. However, there are no tools to effectively trigger and monitor the release of Ag+ ions from Ag nanoparticles. Photoacoustic (PA) imaging is an emerging noninvasive imaging tool, and gold nanorods (AuNRs) are an excellent contrast agent for PA imaging. In this work, we developed Au/Ag hybrid nanoparticles by coating AuNRs with silver (Ag), which decreased their photoacoustic signal. The as-prepared, Ag-coated Au nanorods (Au/AgNRs) are stable under ambient conditions, but the addition of ferricyanide solution (1 mM) results in oxidative etching of the silver shell. The PA contrast is simultaneously recovered as the silver is released, and this PA signal offers noninvasive monitoring of localized release of Ag+ ions. The released Ag+ ions exhibit a strong bactericidal efficacy similar to equivalent free Ag+ ions (AgNO3), and the nanoparticles killed >99.99% of both (Gram-positive) methicillin-resistant Staphylococcus aureus (MRSA, 32 µM Ag+ equivalent) and (Gram-negative) Escherichia coli (8 µM Ag+ equivalent). The theranostic potential of these nanoparticles was demonstrated in a pilot in vivo study. Mice were inoculated with MRSA and Au/AgNRs were subcutaneously implanted followed by silver etching. There was a 730% increase in the PA signal ( p < 0.01) pre- and post-etching, and the bacterial counts in infected tissues of the treated group were reduced by 1000-fold (log CFU/g = 4.15 vs 7.75) versus the untreated control; this treatment efficacy was confirmed with histology. We further showed that these hybrid nanoparticles could release Ag+ after stimulation by reactive oxygen species including hydrogen peroxide and peroxynitrite. These hybrid Au/Ag nanoparticles are a useful theranostic agent for the photoacoustic imaging and treatment of bacterial infections.

Novel Self-assembled Organic Nanoprobe for Molecular Imaging and Treatment of Gram-positive Bacterial Infection.

Background: Increasing bacterial infections as well as a rise in bacterial resistance call for the development of novel and safe antimicrobial agents without inducing bacterial resistance. Nanoparticles (NPs) present some advantages in treating bacterial infections and provide an alternative strategy to discover new antibiotics. Here, we report the development of novel self-assembled fluorescent organic nanoparticles (FONs) with excellent antibacterial efficacy and good biocompatibility. Methods: Self-assembly of 1-(12-(pyridin-1-ium-1-yl)dodecyl)-4-(1,4,5-triphenyl-1H-imidazol-2-yl)pyridin-1-ium (TPIP) in aqueous solution was investigated using dynamic light scattering (DLS) and transmission electron microscopy (TEM). The bacteria were imaged under a laser scanning confocal microscope. We evaluated the antibacterial efficacy of TPIP-FONsin vitro using sugar plate test. The antimicrobial mechanism was explored by SEM. The biocompatibility of the nanoparticles was examined using cytotoxicity test, hemolysis assay, and histological staining. We further tested the antibacterial efficacy of TPIP-FONsin vivo using the S. aureus-infected rats. Results: In aqueous solution, TPIP could self-assemble into nanoparticles (TPIP-FONs) with characteristic aggregation-induced emission (AIE). TPIP-FONs could simultaneously image gram-positive bacteria without the washing process. In vitro antimicrobial activity suggested that TPIP-FONs had excellent antibacterial activity against S. aureus (MIC = 2.0 µg mL-1). Furthermore, TPIP-FONs exhibited intrinsic biocompatibility with mammalian cells, in particular, red blood cells. In vivo studies further demonstrated that TPIP-FONs had excellent antibacterial efficacy and significantly reduced bacterial load in the infectious sites. Conclusion: The integrated design of bacterial imaging and antibacterial functions in the self-assembled small molecules provides a promising strategy for the development of novel antimicrobial nanomaterials.

Intracavitary and Systemic Daptomycin for Successful Treatment of a Postpneumonectomy Intrathoracic Infection.

Treatment of an infected postpneumonectomy cavity is very difficult. We present a patient with an infection of a postpneumonectomy cavity by Staphylococcus epidermidis treated with local daptomycin for different dwell times, maintaining high antibiotic levels above the MIC. Clinical and microbiological cure were achieved successfully.

A novel, multi-barrier, drug eluting calcium sulfate/biphasic calcium phosphate biodegradable composite bone cement for treatment of experimental MRSA osteomyelitis in rabbit model.

This article discloses the development of an effective and versatile technology to prepare a novel antibiotics-loaded biodegradable composite bone cement to treat methicillin-resistant Staphylococcal (MRSA) osteomyelitis and reports its detail in vitro characterization, drug loading efficiency, physico-mechanical properties, drug elution in simulated body fluid (SBF) and human plasma, merits and demerits over poly-methyl methacrylate (PMMA) cement. Chronic osteomyelitis in rabbit tibia (42) was induced by MRSA and composite cement was implanted to evaluate its safety and efficacy over PMMA cement and parenteral treated animals with histopathology, radiographs, bone/plasma drugs concentration, and SEM for 90days. The composite cement showed higher setting time, degradability, pH rise, injectability, in vitro drug elution but lesser mechanical strength than PMMA cement. Antibiotics release from cement beads was faster in SBF than plasma. Further, in vivo antibiotics elution from composite (42days) showed effective concentration against MRSA without eliciting drug-toxicity. Platelets activation by composite was an extraordinary feature. The in vivo studies also proved the superiority of composite cement than other treatment methods in terms of faster infection control and osteosynthesis. Based particularly on drug elution and in vivo results, this newly developed cement can successfully be used in clinical cases of chronic osteomyelitis.

Efficacy of vancomycin-releasing biodegradable poly(lactide-co-glycolide) antibiotics beads for treatment of experimental bone infection due to Staphylococcus aureus.

BACKGROUND: Clinical experience and animal studies have suggested that positron emission tomography (PET) using fluorine-18-labeled fluorodeoxyglucose ((18)F-FDG) may be promising for imaging of bone infections. In this study, we aimed to establish the accuracy of (18)F-FDG PET scanning for monitoring the response to poly(lactide-co-glycolide) (PLGA) vancomycin beads for treatment of bone infection. METHODS: PLGA was mixed with vancomycin and hot-compress molded to form antibiotic beads. In vitro, elution assays and bacterial inhibition tests were employed to characterize the released antibiotics. In vivo, cylindrical cavities were made in six adult male New Zealand white rabbits, and Staphylococcus aureus or saline was injected into the cavity to create a bone infection. After 2 weeks, the infection was confirmed by bacterial cultures, and the defect was filled with PLGA vancomycin beads. The treatment response was monitored by (18)F-FDG PET. RESULTS: The biodegradable beads released high concentrations of vancomycin (well above the breakpoint sensitivity concentration) for treatment of bone infection. In bacterial inhibition tests, the diameter of the sample inhibition zone ranged from 6.5 to 10 mm, which was equivalent to 12.5-100 % relative activity. (18)F-FDG PET results showed that uncomplicated bone healing was associated with a temporary increase in (18)F-FDG uptake at 2 weeks, with return to near baseline at 6 weeks. In the infected animals, localized infection resulted in intense continuous uptake of (18)F-FDG, which was higher than that in uncomplicated healing bones. Bone infection was confirmed with positive bacterial cultures. In vancomycin-treated animals, data showed rapidly decreasing amounts of (18)F-FDG uptake after treatment. CONCLUSIONS: In vitro and in vivo analyses showed that the use of biodegradable PLGA vancomycin beads successfully eradicated S. aureus infection in damaged bone.

Diagnosis and treatment of bacteremia and endocarditis due to Staphylococcus aureus. A clinical guideline from the Spanish Society of Clinical Microbiology and Infectious Diseases (SEIMC).

Both bacteremia and infective endocarditis caused by Staphylococcus aureus are common and severe diseases. The prognosis may darken not infrequently, especially in the presence of intracardiac devices or methicillin-resistance. Indeed, the optimization of the antimicrobial therapy is a key step in the outcome of these infections. The high rates of treatment failure and the increasing interest in the influence of vancomycin susceptibility in the outcome of infections caused by both methicillin-susceptible and -resistant isolates has led to the research of novel therapeutic schemes. Specifically, the interest raised in recent years on the new antimicrobials with activity against methicillin-resistant staphylococci has been also extended to infections caused by susceptible strains, which still carry the most important burden of infection. Recent clinical and experimental research has focused in the activity of new combinations of antimicrobials, their indication and role still being debatable. Also, the impact of an appropriate empirical antimicrobial treatment has acquired relevance in recent years. Finally, it is noteworthy the impact of the implementation of a systematic bundle of measures for improving the outcome. The aim of this clinical guideline is to provide an ensemble of recommendations in order to improve the treatment and prognosis of bacteremia and infective endocarditis caused by S. aureus, in accordance to the latest evidence published.

Executive summary of the diagnosis and treatment of bacteremia and endocarditis due to Staphylococcus aureus. A clinical guideline from the Spanish Society of Clinical Microbiology and Infectious Diseases (SEIMC).

Bacteremia and infective endocarditis caused by Staphylococcus aureus are common and severe diseases. Optimization of treatment is fundamental in the prognosis of these infections. The high rates of treatment failure and the increasing interest in the influence of vancomycin susceptibility in the outcome of infections caused by both methicillin-susceptible and -resistant isolates have led to research on novel therapeutic schemes. The interest in the new antimicrobials with activity against methicillin-resistant staphylococci has been extended to susceptible strains, which still carry the most important burden of infection. New combinations of antimicrobials have been investigated in experimental and clinical studies, but their role is still being debated. Also, the appropriateness of the initial empirical therapy has acquired relevance in recent years. The aim of this guideline is to update the 2009 guidelines and to provide an ensemble of recommendations in order to improve the treatment of staphylococcal bacteremia and infective endocarditis, in accordance with the latest published evidence.

Infectious Complication Following Midface Reconstruction With Calcified Triglyceride.

This case report describes an infectious complication related to the use of calcified triglyceride (Kryptonite Bone Cement) in post-traumatic midface reconstruction. Ultimately, the infected material required removal, and the facial deformity was repaired with subsequent procedures. The literature suggests that bone cement products should be used with caution when in contact with the paranasal sinuses.

Dual-delivery of vancomycin and icariin from an injectable calcium phosphate cement-release system for controlling infection and improving bone healing.

Infectious bone diseases following severely contaminated open fractures are frequently encountered in clinical practice. It is difficult to successfully repair bone and control infection at the same time. To identify a better treatment method, we prepared a dual-drug release system that was comprised of icariin (IC, a natural osteoinductive molecule), vancomycin (VA) and injectable calcium phosphate cement (CPC). The ultrastructure of the dual-drug release system was evaluated by scanning electron microscopy and the biocompatibility was assessed by cell culture. In addition, the release kinetics of IC and VA were respectively investigated by using high­performance liquid chromatography. Finally, this system was used to repair Staphylococcus aureus-contaminated bone defects in a rabbit model. Twelve weeks after the implantation of IC-VA/CPC, the contaminated bone defects were completely repaired, with significantly improved formation of lamellar bone and recanalization of the marrow cavity compared with the controls (CPC without antibiotics or osteoinductive agent). These results demonstrate that this dual-drug release system, with its concomitant antibiotic and osteoinductive properties, has significant potential for the treatment of contaminated bone injury or infectious bone disease.

A lipid-and-polymer-based novel local drug delivery system--BonyPid™: from physicochemical aspects to therapy of bacterially infected bones.

Bacterial infection of bone may result in bone destruction and is difficult to cure due to poor accessibility to bone of systemically-administrated antibiotic and poor performance of currently available local antibacterial treatments. We developed a novel local drug delivery system based on self-assembly of specific familiar lipids and polymers that encapsulate the desired drug (exemplified by doxycycline). The entrapped doxycycline present in the anhydrous environment of the formulation is fully protected from long-term water-exposure-related degradation. The fine coating of the tricalcium phosphate bone filler by this doxycycline-containing formulation (BonyPid™) is capable of releasing intact and active drug at a steady, zero-order rate for a predetermined period of up to 30 days and in amount sufficient to achieve therapy potentially capable of eliminating the contaminating bacteria. Therefore a clinical evaluation is proposed for testing the efficacy and toxicity of BonyPid for therapy of bacterial bone infections.

Antiinflammatory effect of low-level laser therapy on Staphylococcus epidermidis endophthalmitis in rabbits.

A rabbit model of endophthalmitis was established to evaluate the antiinflammatory effect of low-level laser therapy (LLLT) as an adjunct to treatment for Staphylococcus epidermidis endophthalmitis. Rabbits were randomly divided into three groups to receive intravitreal injections into their left eye: group A received 0.5 mg vancomycin (100 µl), group B received 0.5 mg vancomycin + 0.2 mg dexamethasone (100 µl), and group C received 0.5 mg vancomycin (100 µl) and continuous wave semiconductor laser irradiation (10 mW, λ = 632 nm) focused on the pupil. Slit lamp examination and B-mode ultrasonography were conducted to evaluate the symptoms of endophthalmitis. Polymorphonuclear cells and tumour necrosis factor alpha (TNF-α) in aqueous fluid were measured at 0 h, and 1, 2, 3, 7 and 15 days. A histology test was conducted at 15 days. B-mode ultrasonography and histology revealed that groups B and C had less inflammation than group A at 15 days. Groups B and C had fewer polymorphonuclear cells and lower levels of TNF-α in aqueous fluid than group A at 2, 3 and 7 days (P < 0.05). There was no significant difference between groups B and C (P > 0.05). There was no significant difference between groups A, B and C at 15 days (P > 0.05). As an adjunct to vancomycin therapy to treat S. epidermidis endophthalmitis, LLLT has an antiinflammatory effect similar to that of dexamethasone.

In vitro and in vivo efficacies of teicoplanin-loaded calcium sulfate for treatment of chronic methicillin-resistant Staphylococcus aureus osteomyelitis.

The in vitro and in vivo therapeutic efficacies of teicoplanin-loaded calcium sulfate (TCS; 10% [wt] teicoplanin) were investigated in a rabbit model of chronic methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis. The in vitro elution characteristics of teicoplanin from TCS pellets were realized by carrying out an evaluation of the release kinetics, recovery rate, and antibacterial activity of the released teicoplanin. Chronic osteomyelitis was induced by inoculating 10(7) CFU of a MRSA strain into the tibial cavity of rabbits. After 3 weeks, the animals were treated by debridement followed by implantation of TCS pellets in group 1, calcium sulfate (CS) pellets alone in group 2, and intravenous (i.v.) teicoplanin (6 mg/kg of body weight every 12 h for three doses and then every 24 h up to 4 weeks) in group 3. Animals in group 4 were left untreated. After 6 weeks, the efficacy of the osteomyelitis treatment was evaluated by hematological, radiological, microbiological, and histological examinations. In vitro elution studies showed sustained release of teicoplanin at a therapeutic level over a time period of 3 weeks. The released teicoplanin maintained its antibacterial activity. In vivo, the best therapeutic effect was observed in animals treated with TCS pellets, resulting in significantly lower radiological and histological scores, lower positive rates of MRSA culture and bacterial load, and excellent bone regeneration compared with those treated by CS alone or i.v. teicoplanin, without any local or systemic adverse effects. TCS pellets are an effective alternative to i.v. teicoplanin for the treatment of chronic MRSA osteomyelitis, particularly because teicoplanin is delivered locally while the TCS pellets simultaneously promote bone defect repair.

Treatment of vancomycin-intermediate Staphylococcus aureus (VISA) endocarditis with linezolid.

We report a case of infective endocarditis due to vancomycin-intermediate Staphylococcus aureus (VISA). This was treated with a combination of intravenous linezolid and fusidic acid. Cure was achieved without surgical intervention.

An imaging analysis of (99m)Tc-UBI (29-41) uptake in S. aureus infected thighs of rabbits on ciprofloxacin treatment.

PURPOSE: The uptake of (99m)Tc-UBI (29-41) was evaluated at sites of bacterial infections in rabbits before and after treatment with ciprofloxacin. METHODS: Staphylococcus aureus susceptible to ciprofloxacin was used to induce a focal infection in each rabbit of group 1 (G1), group 2 (G2), and group 3 (G3) with 2 x 10(4), 2 x 10(6), and 2 x 10(8) colony forming units (CFU), respectively. After 24 h, images of infected thighs (target: T) and contralateral thighs (nontarget: NT) were acquired. Animals then received ciprofloxacin intramuscularly for 5 days followed by imaging on the third and fifth days. The control group 4 (G4) was imaged at days 1, 3, and 5 under the same acquisition parameters. Group 5 (G5) was employed to study biodistribution of the peptide. RESULTS: Increases in (T/NT) ratios in G1, G2, and G3 were observed from 5 min onwards with maximum values at 60 min. G3 revealed the highest accumulation of the peptide. Growth of the same strain of S. aureus on blood agar medium was visualized after fine needle aspiration. After ciprofloxacin treatment, the images for G1-G3 resulted in significantly decreased (P < 0.05) T/NT values on the third and fifth days that correlated with reduction in number of viable bacteria. No significant difference (P < 0.05) in left to right thigh ratios in the control group (G4) was observed. Biodistribution of the peptide showed rapid removal of tracer from circulation through the kidneys. CONCLUSIONS: ( 99m ) Tc-UBI (29-41) accumulation directly correlates with the number of viable bacteria. This infection localization agent can be utilized for monitoring efficacy and duration of antibiotic treatment.

PMMA is superior to hydroxyapatite for colony reduction in induced osteomyelitis.

Staphylococcus aureus infection is a serious complication in patients receiving orthopaedic implants. Treatment with antibiotic-loaded cements can deliver high local concentrations and reduce toxic side effects associated with systemic antibiotic administration, but polymethylmethacrylate cement is nondegradable and may necessitate additional surgery for removal. Previous studies provide support for hydroxyapatite as a biodegradable carrier, but consensus has not been achieved. We hypothesized vancomycin-loaded hydroxyapatite was superior to vancomycin-loaded polymethylmethacrylate in reducing the number of bacterial colony-forming units in the setting of osteomyelitis. Osteomyelitis was induced in rats using an established model. Animals then were randomly assigned to a control group (no antibiotics), a group treated with vancomycin-loaded polymethylmethacry-late, and two groups treated with hydroxyapatite loaded with either low-dose or high-dose vancomycin. After 6 weeks we compared the number of colony-forming units per gram of harvested bone between groups. Vancomycin-loaded hydroxyapatite was inferior to vancomycin-loaded polymethylmethacrylate in reducing the number of bacterial colony-forming units and vancomycin-loaded polymethylmethacry-late was superior to the control group. We observed no difference between low- and high-dose vancomycin-loaded hydroxyapatite groups. The poor handling properties of hydroxyapatite paste may explain these findings. Based on these results, a hydroxyapatite carrier cannot be recommended for the treatment of osteomyelitis.