Synergistic interactions of essential oil components with antibiotics against multidrug-resistant Corynebacterium striatum.

AIM: In this study, it was aimed to examine the antibacterial activity of the essential oil components (EOCs), carvacrol (CAR), cinnamaldehyde (CIN), thymol (TH), alpha pinene (α-PN), eucalyptol (EU), limonene (LIM), and the antibiotics, linezolid (LZD), vancomycin (VAN), gentamicin (GEN), ciprofloxacin (CIP), clindamycin (CLN), and penicillin (PEN) against 50 multidrug resistant Corynebacterium striatum strains, and the synergistic interactions of CAR and CIN with the antibiotics against 10 randomly selected Coryne. striatum strains to explore synergistic interactions to determine if their combined use could enhance antibiotic activity and potentially reduce resistance. METHODS AND RESULTS: The activity of the EOCs and the antibiotics against Coryne. striatum strains isolated from clinical specimens, was examined by broth microdilution method. The synergistic interactions of the EOCs with the antibiotics against 10 randomly selected Coryne. striatum strains were determined by checkerboard method. EOCs, CIN, and CAR and antibiotics, LZD, VAN, GEN, CIP, and CLN were detected to have antibacterial activity against Coryne. striatum strains alone and either synergistic interactions were observed in combinations of the antibiotics with EOCs. CONCLUSIONS: All Coryne. striatum strains were determined to be susceptible to VAN and LZD and resistant to GEN, PEN, CIP, and CLN. Synergistic interactions were observed in all combinations of antibiotics tested with CAR and CIN.

Investigating the in vitro antibacterial efficacy of composite bone cement incorporating natural product-based monomers and gentamicin.

OBJECTIVE: The objective of this study is to investigate the impact of four natural product extracts, namely, aloe-emodin, quercetin, curcumin, and tannic acid, on the in vitro bacteriostatic properties and biocompatibility of gentamicin-loaded bone cement and to establish an experimental groundwork supporting the clinical utility of antibiotic-loaded bone cements (ALBC). METHODS: Based on the components, the bone cement samples were categorized as follows: the gentamicin combined with aloe-emodin group, the gentamicin combined with quercetin group, the gentamicin combined with curcumin group, the gentamicin combined with tannic acid group, the gentamicin group, the aloe-emodin group, the quercetin group, the curcumin group, and the tannic acid group. Using the disk diffusion test, we investigated the antibacterial properties of the bone cement material against Staphylococcus aureus (n = 4). We tested cell toxicity and proliferation using the cell counting kit-8 (CCK-8) and examined the biocompatibility of bone cement materials. RESULTS: The combination of gentamicin with the four natural product extracts resulted in significantly larger diameters of inhibition zones compared to gentamicin alone, and the difference was statistically significant (P < 0.05). Except for the groups containing tannic acid, cells in all other groups showed good proliferation across varying time intervals without displaying significant cytotoxicity (P < 0.05). CONCLUSION: In this study, aloe-emodin, quercetin, curcumin, and tannic acid were capable of enhancing the in vitro antibacterial performance of gentamicin-loaded bone cement against S. aureus. While the groups containing tannic acid displayed moderate cytotoxicity in in vitro cell culture, all other groups showed no discernible cytotoxic effects.

Assessment of performance and safety of Corneal Chamber hypothermic storage medium and PSS-L corneal rinsing solution in human and porcine corneas.

PURPOSE: To prove the safety and performance of the hypothermic corneal storage medium "Corneal Chamber" and the rinsing solution "PSS-L" in support of the new Conformité Européenne (CE) certification process in accordance with the Medical Device Regulation. METHODS: Fifteen (n=15) human donor corneas and 11 (n=11) porcine corneas were evaluated for the following parameters: endothelial cell density (ECD) and mortality, percentage of hexagonal cells (HEX%), coefficient of cellular area variation (CV%) and corneal transparency at Day 0 and after 14±1 days of storage in Corneal Chamber medium at 2-8°C. Then, the same parameters were assessed after rinsing of corneas in PSS-L for 1 min at room temperature. Evaluation of gentamicin sulfate carryover after corneal storage and PSS-L rinsing was performed by ultra-high performance liquid chromatography analysis on human corneas homogenates. RESULTS: Human and porcine corneas stored in Corneal Chamber medium showed a good overall quality of the tissue according to the quality parameters evaluated. In particular, mean ECD, HEX% and CV% did not show statistically significant changes at the end of storage and endothelial mortality increased to 3.1±3.3 and 7.8±3.5% in human and porcine corneas, respectively. Tissue rinsing with PSS-L did not affect the quality parameters evaluated before and gentamicin sulfate residues were absent in human corneas. CONCLUSIONS: Corneal preservation in Corneal Chamber medium at 2-8°C for 14 days and the corneal rinse with PSS-L are safe and effective procedures allowing the preservation of the corneal quality parameters as well as the complete elimination of gentamicin sulfate from the tissues before transplantation.Cite Now.

Methyl cellulose/okra mucilage composite films, functionalized with Hypericum perforatum oil and gentamicin, as a potential wound dressing.

There is a growing demand for the development of functional wound dressings enriched with bioactive natural compounds to improve the quality of life of the population by accelerating the healing process of chronic wounds. In this regard, a functional composite film of okra mucilage (OM) and methylcellulose (MC) incorporated with Hypericum perforatum oil (Hp) and gentamicin (G) was prepared and characterized as a wound dressing. Increasing Hp resulted in improved film properties with a more porous structure, higher WVTR, and lower surface hydrophobicity. Furthermore, incorporating Hp into OM:MC films led to increased elongation at the break while reducing the tensile strength of the films. The highest values of total antioxidant capacity (1.09-1.16 mM trolox equivalent) and total phenolic content (13.76-16.94 µg GA equivalent mL-1) were measured in the composite films containing the highest Hp concentration (1.5 %). In addition, OM:MC/HpG composite films exhibited significant antibacterial activity against both E. coli and S. aureus and prevented the transmission of these bacteria through the films. Hp incorporation reduced the cytotoxic effects of OM:MC films on BJ cells and increased the wound closure rate in vitro. In conclusion, the developed OM:MC/HpG composite film can be a promising candidate as a novel wound dressing with its superior properties.

VesiX cetylpyridinium chloride is rapidly bactericidal and reduces uropathogenic Escherichia coli bladder epithelial cell invasion in vitro.

Management of urinary tract infection (UTI) in postmenopausal women can be challenging. The recent rise in resistance to most of the available oral antibiotic options together with high recurrence rate in postmenopausal women has further complicated treatment of UTI. As such, intravesical instillations of antibiotics like gentamicin are being investigated as an alternative to oral antibiotic therapies. This study evaluates the efficacy of the candidate intravesical therapeutic VesiX, a solution containing the cationic detergent Cetylpyridinium chloride, against a broad range of uropathogenic bacterial species clinically isolated from postmenopausal women with recurrent UTI (rUTI). We also evaluate the cytotoxicity of VesiX against cultured bladder epithelial cells and find that low concentrations of 0.0063% and 0.0125% provide significant bactericidal effect toward diverse bacterial species including uropathogenic Escherichia coli (UPEC), Klebsiella pneumoniae, Enterococcus faecalis, Pseudomonas aeruginosa, and Proteus mirabilis while minimizing cytotoxic effects against cultured 5637 bladder epithelial cells. Lastly, to begin to evaluate the potential utility of using VesiX in combination therapy with existing intravesical therapies for rUTI, we investigate the combined effects of VesiX and the intravesical antibiotic gentamicin. We find that VesiX and gentamicin are not antagonistic and are able to reduce levels of intracellular UPEC in cultured bladder epithelial cells. IMPORTANCE: When urinary tract infections (UTIs), which affect over 50% of women, become resistant to available antibiotic therapies dangerous complications like kidney infection and lethal sepsis can occur. New therapeutic paradigms are needed to expand our arsenal against these difficult to manage infections. Our study investigates VesiX, a Cetylpyridinium chloride (CPC)-based therapeutic, as a candidate broad-spectrum antimicrobial agent for use in bladder instillation therapy for antibiotic-resistant UTI. CPC is a cationic surfactant that is FDA-approved for use in mouthwashes and is used as a food additive but has not been extensively evaluated as a UTI therapeutic. Our study is the first to investigate its rapid bactericidal kinetics against diverse uropathogenic bacterial species isolated from postmenopausal women with recurrent UTI and host cytotoxicity. We also report that together with the FDA-approved bladder-instillation agent gentamicin, VesiX was able to significantly reduce intracellular populations of uropathogenic bacteria in cultured bladder epithelial cells.

Mechanism and antibacterial synergies of poly(Dabco-BBAC) nanoparticles against multi-drug resistant Pseudomonas aeruginosa isolates from human burns.

Multi-drug resistant bacteria are a major problem in the treatment of infectious diseases, such as pneumonia, meningitis, or even coronavirus disease 2019 (COVID-19). Cationic nanopolymers are a new type of antimicrobial agent with high efficiency. We synthesized and characterized cationic polymer based on 1,4-diazabicyclo [2.2.2] octane (DABCO) and Bis (bromoacetyl)cystamine (BBAC), named poly (DABCO-BBAC) nanoparticles(NPs), and produced 150 nm diameter NPs. The antibacterial activity of poly (DABCO-BBAC) against eight multi drug resistant (MDR) Pseudomonas aeruginosa isolates from human burns, its possible synergistic effect with gentamicin, and the mechanism of action were examined. Poly(DABCO-BBAC) could effectively inhibit and kill bacterial strains at a very low concentration calculated by minimum inhibitory concentration (MIC) assay. Nevertheless, its synergism index with gentamicin showed an indifferent effect. Moreover, transmission electron microscopy and lipid peroxidation assays showed that poly (DABCO-BBAC) distorted and damaged the bacterial cell wall. These results suggest that the poly (DABCO-BBAC) could be an effective antibacterial agent for MDR clinical pathogens.

Bone marrow mesenchymal stem cells response on collagen/hyaluronan/chondroitin scaffold enriched with gentamicin -loaded gelatin microparticles for skin tissue engineering.

The repair and functional reconstruction of large skin defects caused by burn remains an intractable clinical problem. Collagen type I (ColI) was extracted from carp scales and confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis ultraviolet adsorption spectra and automatic amino acid analyzer. Then the scaffolds containing the purified ColI, hyaluronic acid (HA) and chondroitin sulfate (CS) were constructed and examined. The results showed that the scaffold (ColI:CS:HA=9:1:1) had larger pore diameter, porosity, water absorption, degradation rate and tensile strength. gentamycin sulphate (GS) - gelatin microspheres (GMSs) were prepared by emulsion cross-linking method. The drug release study of the ColI-CS-HA-GS/GMSs scaffold with antibacterial property showed a prolonged, continuous, and sustained release of GS. The bone marrow mesenchymal stem cells (BMSCs) were extracted from rat and inoculated into the ColI-HA-CS-GS/GMSs scaffold. The results performed that the scaffold could accelerate proliferation of the BMSCs and wound healing.

Nanocomposite orthopaedic bone cement combining long-acting dual antimicrobial drugs.

Antibiotic loaded bone cements are widely used in total joint replacement (TJR); despite many limitations such as a burst release which leads to antibiotic concentration below inhibitory levels and possibly contributing to the selection of antibiotic resistant strains. In order to address such limitations and to simultaneously address antibiotic resistance and short-term antimicrobial activity, we developed a nanocomposite bone cement capable of providing a controlled release of antimicrobial agents from bone cement to act as prophylaxis or treatment against prosthetic joint infections (PJIs). Gentamicin and chlorhexidine were loaded in combination on silica nanoparticles surface using layer-by-layer coating technique (LbL) combining hydrolysable and non-hydrolysable polymers. The drug release from the nanocomposite continued for >50 days at concentrations higher than the commercial formulation containing the same amount of antimicrobial drugs, where burst release for few days were observed. Moreover, the nanocomposite bone cement showed superior antimicrobial inhibition without adversely affecting the mechanical properties or the ability of osteoblasts to grow. In vivo experiments with an infected bone lesion model along with mass-spectrometric analysis also provided further evidence of efficacy and safety of the implanted nanocomposite material as well as its prolonged drug eluting profile. The developed nanocomposite bone cement has the potential to reduce PJIs and enable treatment of resistant established infections; moreover, the newly developed LbL based nano-delivery system may also have wider applications in reducing the threat posed by antimicrobial resistance.

Measurement of Salmonella enterica Internalization and Vacuole Lysis in Epithelial Cells.

Establishment of an intracellular niche within mammalian cells is key to the pathogenesis of the gastrointestinal bacterium, Salmonella enterica serovar Typhimurium (S. Typhimurium). Here we will describe how to study the internalization of S. Typhimurium into human epithelial cells using the gentamicin protection assay. The assay takes advantage of the relatively poor penetration of gentamicin into mammalian cells; internalized bacteria are effectively protected from its antibacterial actions. A second assay, the chloroquine (CHQ) resistance assay, can be used to determine the proportion of internalized bacteria that have lysed or damaged their Salmonella-containing vacuole and are therefore residing within the cytosol. Its application to the quantification of cytosolic S. Typhimurium in epithelial cells will also be presented. Together, these protocols provide an inexpensive, rapid, and sensitive quantitative measure of bacterial internalization and vacuole lysis by S. Typhimurium.

Fructose-enabled killing of antibiotic-resistant Salmonella enteritidis by gentamicin: Insight from reprogramming metabolomics.

Salmonella enterica is a food-borne pathogen that poses a severe threat to both poultry production and human health. Antibiotics are critical for the initial treatment of bacterial infections. However, the overuse and misuse of antibiotics results in the rapid evolution of antibiotic-resistant bacteria, and the discovery and development of new antibiotics are declining. Therefore, understanding antibiotic resistance mechanisms and developing novel control measures are essential. In the present study, GC-MS-based metabolomics analysis was performed to determine the metabolic profile of gentamicin sensitive (SE-S) and resistant (SE-R) S. enterica. Fructose was identified as a crucial biomarker. Further analysis demonstrated a global depressed central carbon metabolism and energy metabolism in SE-R. The decrease in the pyruvate cycle reduces the production of NADH and ATP, causing a decrease in membrane potential, which contributes to gentamicin resistance. Exogenous fructose potentiated the effectiveness of gentamicin in killing SE-R by promoting the pyruvate cycle, NADH, ATP and membrane potential, thereby increasing gentamicin intake. Further, fructose plus gentamicin improved the survival rate of chicken infected with gentamicin-resistant Salmonella in vivo. Given that metabolite structures are conserved across species, fructose identified from bacteria could be used as a biomarker for breeding disease-resistant phenotypes in chicken. Therefore, a novel strategy is proposed for fighting against antibiotic-resistant S. enterica, including exploring molecules suppressed by antibiotics and providing a new approach to find pathogen targets for disease resistance in chicken breeding.

Dual-Function Hydrogel Dressings with a Dynamic Exchange of Iron Ions and an Antibiotic Drug for Treatment of Infected Wounds.

Bacterial infection is a major problem with diabetic wounds that may result in nonhealing chronic ulcers. Here, we report an approach to antibacterial hydrogel dressings for enhanced treatment of infected skin wounds. A fibrous hydrogel was derived from cellulose nanocrystals that were modified with dopamine and cross-linked with gelatin. The hydrogel was loaded with gentamicin, an antibiotic drug. Enhanced antibacterial hydrogel performance resulted from (i) a highly specific sequestration of Fe3+ ions (much needed by bacteria) from the wound exudate and (ii) a dynamic exchange between gentamicin released from the hydrogel and Fe3+ ions withdrawn from the wound exudate. Such exchange was possible due to the high value of the binding constant of Fe3+ ions to dopamine. The hydrogel did not affect the metabolic activity of skin-related cells and showed enhanced antibacterial performance against common wound pathogens such as S. aureus and P. aeruginosa. Furthermore, it promoted healing of infected diabetic wounds due to a synergistic antibacterial effect providing the dynamic exchange between Fe3+ ions and gentamicin. This work provides a strategy for the design of dual-function wound dressings, with both starving and killing bacteria and enhanced wound healing performance.

Cold Atmospheric Plasma-Activated Composite Hydrogel for an Enhanced and On-Demand Delivery of Antimicrobials.

We present the concept of a versatile drug-loaded composite hydrogel that can be activated using an argon-based cold atmospheric plasma (CAP) jet to deliver both a drug and CAP-generated molecules, concomitantly, in a tissue target. To demonstrate this concept, we utilized the antibiotic gentamicin that is encapsulated in sodium polyacrylate (PAA) particles, which are dispersed within a poly(vinyl alcohol) (PVA) hydrogel matrix. The final product is a gentamicin-PAA-PVA composite hydrogel suitable for an on-demand triggered release using CAP. We show that by activating using CAP, we can effectively release gentamicin from the hydrogel and also eradicate the bacteria effectively, both in the planktonic state and within a biofilm. Besides gentamicin, we also successfully demonstrate the applicability of the CAP-activated composite hydrogel loaded with other antimicrobial agents such as cetrimide and silver. This concept of a composite hydrogel is potentially adaptable to a range of therapeutics (such as antimicrobials, anticancer agents, and nanoparticles) and activatable using any dielectric barrier discharge CAP device.

Can platelet-rich fibrin act as a natural carrier for antibiotics delivery? A proof-of-concept study for oral surgical procedures.

OBJECTIVES: Evaluate the role of platelet-rich fibrin (PRF) as a natural carrier for antibiotics delivery through the analysis of drug release and antimicrobial activity. MATERIALS AND METHODS: PRF was prepared according to the L-PRF (leukocyte- and platelet-rich fibrin) protocol. One tube was used as control (without drug), while an increasing amount of gentamicin (0.25 mg, G1; 0.5 mg, G2; 0.75 mg, G3; 1 mg, G4), linezolid (0.5 mg, L1; 1 mg, L2; 1.5 mg, L3; 2 mg, L4), vancomycin (1.25 mg, V1; 2.5 mg, V2; 3.75 mg, V3; 5 mg, V4) was added to the other tubes. At different times the supernatant was collected and analyzed. Strains of E. coli, P. aeruginosa, S. mitis, H. influenzae, S. pneumoniae, S. aureus were used to assess the antimicrobial effect of PRF membranes prepared with the same antibiotics and compared to control PRF. RESULTS: Vancomycin interfered with PRF formation. Gentamicin and linezolid did not change the physical properties of PRF and were released from membranes in the time intervals examined. The inhibition area analysis showed that control PRF had slight antibacterial activity against all tested microorganisms. Gentamicin-PRF had a massive antibacterial activity against all tested microorganisms. Results were similar for linezolid-PRF, except for its antibacterial activity against E. coli and P. aeruginosa that was comparable to control PRF. CONCLUSIONS: PRF loaded with antibiotics allowed the release of antimicrobial drugs in an effective concentration. Using PRF loaded with antibiotics after oral surgery may reduce the risk of post-operative infection, replace or enhance systemic antibiotic therapy while preserving the healing properties of PRF. Further studies are needed to prove that PRF loaded with antibiotics represents a topical antibiotic delivery tool for oral surgical procedures.

Quantitative proteomics reveals reduction in central carbon and energy metabolisms contributes to gentamicin resistance in Staphylococcus aureus.

The emergence of antibiotic resistance greatly increases the difficulty of treating bacterial infections. In order to develop effective treatments, the underlying mechanisms of antibiotic resistance must be understood. In this study, Staphylococcus aureus ATCC6538 strain was passaged in medium with and without gentamicin and obtained lab-evolved gentamicin-resistant S. aureus (RGEN) and gentamicin-sensitive S. aureus (SGEN) strains, respectively. Data-Independent Acquisition (DIA)-based proteomics approach was applied to compare the two strains. A total of 1426 proteins were identified, of which 462 were significantly different: 126 were upregulated and 336 were downregulated in RGEN compared to SGEN. Further analysis found that reduced protein biosynthesis was a characteristic feature in RGEN, related to metabolic suppression. The most differentially expressed proteins were involved in metabolic pathways. In RGEN, central carbon metabolism was dysregulated and energy metabolism decreased. After verification, it was found that the levels of NADH, ATP, and reactive oxygen species (ROS) decreased, and superoxide dismutase and catalase activities increased. These findings suggest that inhibition of central carbon and energy metabolic pathways may play an important role in the resistance of S. aureus to gentamicin, and that gentamicin resistance is associated with oxidative stress. Significance: The overuse and misuse of antibiotics have led to bacterial antibiotic resistance, which is a serious threat to human health. Understanding the mechanisms of antibiotic resistance will help better control these antibiotic-resistant pathogens in the future. The present study characterized the differential proteome of gentamicin-resistant Staphylococcus aureus using the most advanced DIA-based proteomics technology. Many of the differential expressed proteins were related to metabolism, specifically, reduced central carbon and energy metabolism. Lower levels of NADH, ROS, and ATP were detected as a consequence of the reduced metabolism. These results reveal that downregulation of protein expression affecting central carbon and energy metabolisms may play an important role in the resistance of S. aureus to gentamicin.

Mitochondrial transplantation against gentamicin-induced toxicity on rat renal proximal tubular cells: the higher activity of female rat mitochondria.

Mitochondrial dysfunction is a fundamental mechanism leading to drug nephrotoxicity, such as gentamicin-induced nephrotoxicity. Mitochondrial therapy (mitotherapy) or exogenous mitochondria transplantation is a method that can be used to replace dysfunctional mitochondria with healthy mitochondria. This method can help in the treatment of diseases related to mitochondria. In this research, we studied the transplantation effect of freshly isolated mitochondria on the toxicity induced by gentamicin on renal proximal tubular cells (RPTCs). Furthermore, possible gender-related effects on supplying exogenous rat kidney mitochondria on gentamicin-induced RPTCs were investigated. At first, the normality and proper functioning of fresh mitochondria were assessed by measuring mitochondrial succinate dehydrogenase activity (SDH) and changes in mitochondrial membrane potential (MMP). Then, the protective effects of mitochondrial transplantation against gentamicin-induced mitochondrial toxicity were evaluated through parameters including lactate dehydrogenase (LDH) leakiness, reactive oxygen species (ROS) production, lipid peroxidation (LPO) content, reduced glutathione (GSH) level, extracellular oxidized glutathione (GSSG) level, ATP level, MMP collapse, and caspase-3 activity. According to the statistical analysis, transplanting the healthy mitochondria decreased the cytotoxicity, ROS production, MMP collapse, LPO content, GSSG levels, and caspase-3 activity caused by gentamicin in RPTCs. Also, it has caused an increase in the level of ATP and GSH in the RPTCs. Furthermore, higher preventive effects were observed for the female group. According to the current study, mitochondrial transplantation is a potent therapeutic method in xenobiotic-caused nephrotoxicity.

Staphylococcus aureus Breast Implant Infection Isolates Display Recalcitrance To Antibiotic Pocket Irrigants.

Breast implant-associated infections (BIAIs) are the primary complication following placement of breast prostheses in breast cancer reconstruction. Given the prevalence of breast cancer, reconstructive failure due to infection results in significant patient distress and health care expenditures. Thus, effective BIAI prevention strategies are urgently needed. This study tests the efficacy of one infection prevention strategy: the use of a triple antibiotic pocket irrigant (TAPI) against Staphylococcus aureus, the most common cause of BIAIs. TAPI, which consists of 50,000 U bacitracin, 1 g cefazolin, and 80 mg gentamicin diluted in 500 mL of saline, is used to irrigate the breast implant pocket during surgery. We used in vitro and in vivo assays to test the efficacy of each antibiotic in TAPI, as well as TAPI at the concentration used during surgery. We found that planktonically grown S. aureus BIAI isolates displayed susceptibility to gentamicin, cefazolin, and TAPI. However, TAPI treatment enhanced biofilm formation of BIAI strains. Furthermore, we compared TAPI treatment of a S. aureus reference strain (JE2) to a BIAI isolate (117) in a mouse BIAI model. TAPI significantly reduced infection of JE2 at 1 and 7 days postinfection (dpi). In contrast, BIAI strain 117 displayed high bacterial burdens in tissues and implants, which persisted to 14 dpi despite TAPI treatment. Lastly, we demonstrated that TAPI was effective against Pseudomonas aeruginosa reference (PAO1) and BIAI strains in vitro and in vivo. Together, these data suggest that S. aureus BIAI strains employ unique mechanisms to resist antibiotic prophylaxis treatment and promote chronic infection. IMPORTANCE The incidence of breast implant associated infections (BIAIs) following reconstructive surgery postmastectomy remains high, despite the use of prophylactic antibiotic strategies. Thus, surgeons have begun using additional antibiotic-based prevention strategies, including triple antibiotic pocket irrigants (TAPIs). However, these strategies fail to reduce BIAI rates for these patients. To understand why these therapies fail, we assessed the antimicrobial resistance patterns of Staphylococcus aureus strains, the most common cause of BIAI, to the antibiotics in TAPI (bacitracin, cefazolin, and gentamicin). We found that while clinically relevant BIAI isolates were more susceptible to the individual antibiotics compared to a reference strain, TAPI was effective at killing all the strains in vitro. However, in a mouse model, the BIAI isolates displayed recalcitrance to TAPI, which contrasted with the reference strain, which was susceptible. These data suggest that strains causing BIAI may encode specific recalcitrance mechanisms not present within reference strains.

The antibiotics supplemented bone cement improved the masquelet's induced membrane in a rat femur critical size defect model.

BACKGROUND: Masquelet technique is a two-stage surgical procedure used in the treatment of critical-size bone defects (CSD). Adding antibiotics to polymethylmethacrylate (PMMA) is still questionable to create higher quality induced membrane (IM). The aim of the study was to evaluate the effects of three antibiotic-supplemented cement, fusidic acid, teicoplanin, and gentamicin, on osteogenesis and IM progression applied to rat femur CSD model by comparing histopathological, biochemical, and immunohistochemical findings. METHODS: Twenty-eight male rats were divided into four groups control, gentamicin (G), teicoplanin (T), and fusidic acid (FA). A 10 mm CSD was created in rat femurs. In the postoperative 4th week, intracardiac blood samples were collected for biochemical analysis of bone alkaline phosphatase (BALP), osteocalcin (OC), and tumor necrosis factor-alpha (TNF-α) levels. IMs obtained in secondary operation were fixed and prepared for histopathological scoring of membrane progression and immunohistochemical evaluation of rat-specific Transforming Growth Factor-Beta (TGF-ß), Runt-related Transcription Factor 2 (Runx2), and Vascular Endothelial Growth Factor (VEGF) expressions. RESULTS: Levels of BALP and OC in serum didn't change among groups significantly while serum TNF-α levels significantly decreased in all antibiotic groups compared to the control group (P = 0.017). Histological scores of groups FA and T were significantly higher than those of groups Control and G (P = 0.0007). IMs of groups T and FA showed good progression while those of groups Control and G were also moderately progressed. A significant increase in TGF-ß expression was observed in group G and FA (P = 0.001) while a significant increase in the expression of VEGF was observed in groups G and T compared to the control group (P = 0.036). CONCLUSIONS: The bone cement impregnated with thermostable and safe antibiotics, gentamicin, fusidic acid, and teicoplanin can increase osteogenesis and support IM progression by increasing the expressions of TGF-ß and VEGF. Anabolic effects of induced membranes used in the treatment of critical-size bone defects can be enhanced by antibiotic-supplemented PMMAs applied by altering the original technique.

Potassium penicillin and gentamicin pharmacokinetics in healthy conscious and anesthetized horses.

OBJECTIVE: To determine the effects of general anesthesia on the safety and efficacy of co-administered potassium penicillin G (PEN) and gentamicin (GENT) in horses. STUDY DESIGN: Nonrandomized crossover. ANIMALS: Six adult, Thoroughbred horses. METHODS: Horses were administered PEN (22 000 IU/kg IV) and GENT (6.6 mg/kg IV). Plasma samples were collected over a 6 h period and synovial fluid was collected at 30 min and 6 h respectively. Drug administration and sample collection protocols were repeated after at least a 48 hour washout period and induction of anesthesia using xylazine/ketamine and maintenance with isoflurane gas. Drug concentrations were determined using ultrapressure liquid chromatography with mass spectrometry. A 2-compartment model was used to determine pharmacokinetics and differences were determined between conscious and anesthetized horses using paired t-tests (significance P < .05). RESULTS: Potassium penicillin g and GENT had higher minimum plasma concentrations (PEN 0.44 vs. 0.11 µg/mL, P = .002; GENT 3.0 vs. 1.9 µg/mL, P = .009), longer half lives (PEN 71 vs. 59 min, P = .018; GENT 149 vs. 109 min, P = .038), and slower clearances (PEN 3.41 vs. 5.1 mL/kg/min, P = .005; GENT 1.18 vs. 1.48 mL/kg/min, P = .028) in anesthetized horses vs. conscious horses. The PEN concentrations remained above the breakpoint minimum inhibitory concentration (MIC, 0.5 µg/mL) for 332 min in anesthetized vs. 199 min in conscious horses. The GENT concentrations reached 10 times higher than the breakpoint MIC (2 µg/mL) in all horses and were maintained for 58 vs. 59 min in anesthetized and conscious states, respectively. Synovial fluid concentrations were higher in conscious horses vs. anesthetized horses at 30 min for PEN (7.0 vs. 0.93 µg/mL, P < .001) and 30 (5.3 µg/mL vs. 0.79 µg/mL, P < .001) and 360 min (3.4 vs. 1.82 µg/mL, P < .003) for GENT. CONCLUSION: General anesthesia resulted in lower intrasynovial concentrations and delayed clearance of PEN/GENT in horses. CLINICAL SIGNIFICANCE: Redosing healthy anesthetized horses with PEN prior to 4-5 h is not necessary. When administered to anesthetized horses, intravenous PEN/GENT may not reach adequate intrasynovial concentrations to treat or prevent common pathogens. The doses or dosing intervals of antimicrobials administered to horses undergoing anesthesia may need to be adjusted to ensure maintenance of safe and effective plasma concentrations.

A simple label-free method reveals bacterial growth dynamics and antibiotic action in real-time.

Understanding the response of bacteria to environmental stress is hampered by the relative insensitivity of methods to detect growth. This means studies of antibiotic resistance and other physiological methods often take 24 h or longer. We developed and tested a scattered light and detection system (SLIC) to address this challenge, establishing the limit of detection, and time to positive detection of the growth of small inocula. We compared the light-scattering of bacteria grown in varying high and low nutrient liquid medium and the growth dynamics of two closely related organisms. Scattering data was modelled using Gompertz and Broken Stick equations. Bacteria were also exposed meropenem, gentamicin and cefoxitin at a range of concentrations and light scattering of the liquid culture was captured in real-time. We established the limit of detection for SLIC to be between 10 and 100 cfu mL-1 in a volume of 1-2 mL. Quantitative measurement of the different nutrient effects on bacteria were obtained in less than four hours and it was possible to distinguish differences in the growth dynamics of Klebsiella pneumoniae 1705 possessing the BlaKPC betalactamase vs. strain 1706 very rapidly. There was a dose dependent difference in the speed of action of each antibiotic tested at supra-MIC concentrations. The lethal effect of gentamicin and lytic effect of meropenem, and slow bactericidal effect of cefoxitin were demonstrated in real time. Significantly, strains that were sensitive to antibiotics could be identified in seconds. This research demonstrates the critical importance of improving the sensitivity of bacterial detection. This results in more rapid assessment of susceptibility and the ability to capture a wealth of data on the growth dynamics of bacteria. The rapid rate at which killing occurs at supra-MIC concentrations, an important finding that needs to be incorporated into pharmacokinetic and pharmacodynamic models. Importantly, enhanced sensitivity of bacterial detection opens the possibility of susceptibility results being reportable clinically in a few minutes, as we have demonstrated.

Use of peptide-modified nanoparticles as a bacterial cell targeting agent for enhanced antibacterial activity and other biomedical applications.

Bacterial pathogens have posed a serious threat to human health because they are difficult to be eliminated inside cells. Here, an effective design of poly(lactic-co-glycolic) (PLGA) nanoparticles (NPs) modified with antimicrobial peptides and loaded with gentamicin (Gen) was reported with enhanced antibacterial activity and cellular internalization ability. The results showed that the drug loading capacity and encapsulation efficiency of OVTp12-modified NPs were 7.55 % and 81.3 %, respectively. We observed that OVTp12 and OVTp12-modified NPs significantly increased the interaction with Staphylococcus aureus cells. Moreover, OVTp12-modified NPs showed an effective inhibitory effect on S. aureus with low cytotoxicity. The results of cell internalization indicated that OVTp12-modified NPs were markedly higher than that of unmodified nanoparticles when incubated with MC3T3-E1 cells. In conclusion, the bacterial cell-targeting ability of this antimicrobial peptide provides advantages for the treatment of intracellular bacterial infections.