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Photo-inactivation and efflux pump inhibition of methicillin resistant Staphylococcus aureus using thiolated cobalt doped ZnO nanoparticles
摘要： Multidrug resistance (MDR) in bacteria is a major concern these days. One of the reasons is the mutation in efflux pump that prevents the retention of antibiotics and drugs in the bacterial cell. The current work is a step to overcome MDR in bacteria via inhibition of efflux pump and further photoinhibition by thiolated chitosan coated cobalt doped zinc oxide nanoparticles (Co-ZnO) in visible light. Co-ZnO were synthesized in a size range of 40–60 nm. Antibacterial activity of the Co-ZnO against methicillin resistant Staphylococcus aureus (MRSA) was found 100% at a concentration of 10 μg/ml upon activation in sunlight for 15 min. Interestingly, it was found that cobalt as a dopant was able to increase the photodynamic and photothermal activity of Co-ZnO, as in dark conditions, there was only 3–5% of inhibition at 10 μg/ml of nanoparticle concentration. Upon excitation in light, these nanoparticles were able to generate reactive oxygen species (ROS) with a quantum yield of 0.23 ± 0.034. The nanoparticles were also generating heat, Because of the magnetic nature, thus helping in more killing. Thiolated chitosan further helped in blocking the efflux pump of MRSA. The current nanoparticles were also found biocompatible on human red blood cells (LD50 = 214 μg/ml). These data suggest that the MRSA killing ability was facilitated through efflux inhibition and oxidative stress upon excitation in visible light hence, were in accordance with previous findings.
关键词： Multidrug resistant bacteria,Biocompatibility,ZnO nanoparticles,Photo-inactivation,ROS,MRSA
更新于2025-09-19 17:15:36
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Controlled Hydrothermal Synthesis of Bismuth Vanadate Nano-articulate Structures: Photooxidation of Methicillin Resistant Staphylococcus aureus and Organic Dyes
摘要： Scheelite monoclinic bismuth vanadate nano-articulate crystals have been synthesized by using 1% sodium dodecyl sulphate as surfactant and ammonia as pH controlling agent at 180?C for 4 hr (at pH = 0, 1, 3, 6 and 8) under facile hydrothermal conditions. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS). XRD and FE-SEM confirm the formation of monoclinic structures at all pH ranges and a preferential crystal growth (crystallite size 20-30 nm) has been observed along {040} facet with increase in NH4OH concentration. This selective growth resulted in structure enhanced performance of photocatalytic degradation of organic dyes and bacterial inactivation. Photocatalytic inactivation of methicillin resistant Staphylococcus aureus (MRSA) and comparison of the results to the oxidation of Procion Red MX-5B, Alizarin Red S and Cibacron Brilliant Yellow 3G-P dyes using bismuth vanadates has been reported originally in this paper.
关键词： Nano-articulate crystals,MRSA inactivation,Catalytic properties,Preferential growth
更新于2025-09-16 10:30:52
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Biofunctionalization of selective laser melted porous titanium using silver and zinc nanoparticles to prevent infections by antibiotic-resistant bacteria
摘要： Antibiotic-resistant bacteria are frequently involved in implant-associated infections (IAIs), making the treatment of these infections even more challenging. Therefore, multifunctional implant surfaces that simultaneously possess antibacterial activity and induce osseointegration are highly desired in order to prevent IAIs. The incorporation of multiple inorganic antibacterial agents onto the implant surface may aid in generating synergistic antibacterial behavior against a wide microbial spectrum while reducing the occurrence of bacterial resistance. In this study, porous titanium implants synthesized by selective laser melting (SLM) were biofunctionalized with plasma electrolytic oxidation (PEO) using electrolytes based on Ca/P species as well as silver and zinc nanoparticles in ratios from 0 to 100% that were tightly embedded into the growing titanium oxide layer. After the surface bio-functionalization process, silver and zinc ions were released from the implant surfaces for at least 28 days resulting in antibacterial leaching activity against methicillin-resistant Staphylococcus aureus (MRSA). Furthermore, the biofunctionalized implants generated reactive oxygen species, thereby contributing to antibacterial contact-killing. While implant surfaces containing up to 75% silver and 25% zinc nanoparticles fully eradicated both adherent and planktonic bacteria in vitro as well as in an ex vivo experiment performed using murine femora, solely zinc-bearing surfaces did not. The minimum inhibitory and bactericidal concentrations determined for different combinations of both types of ions confirmed the presence of a strong synergistic antibacterial behavior, which could be exploited to reduce the amount of required silver ions by two orders of magnitude (i.e., 120 folds). At the same time, the zinc bearing surfaces enhanced the metabolic activity of pre-osteoblasts after 3, 7, and 11 days. Altogether, implant biofunctionalization by PEO with silver and zinc nanoparticles is a fruitful strategy for the synthesis of multifunctional surfaces on orthopedic implants and the prevention of IAIs caused by antibiotic-resistant bacteria.
关键词： Multifunctional biomaterials,silver and zinc nanoparticles,implant-associated infections,plasma electrolytic oxidation,additive manufacturing,MRSA
更新于2025-09-16 10:30:52
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Evaluation of Staphylococcus aureus Subtyping Module for Methicillin-Resistant Staphylococcus aureus Detection Based on Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry
摘要： A recent developed S. aureus subtyping module for rapidly differentiate methicillin-resistant Staphylococcus aureus (MRSA) from methicillin-susceptible S. aureus (MSSA) had been introduced into China. The principle of this method was to identify the methicillin resistance through detection of a specific phenol soluble modulin-mec peak (PSM-mec) by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). A total of 347 non-duplicated S. aureus strains were collected from the Second Affiliated Hospital of Zhejiang University School of Medicine during January 2014 to February 2019. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the automated subtyping module in identifying MRSA were evaluated. The specificity and PPV of this method were both 100% and the sensitivity was 60.2%. PSM-bearing MRSA were reported with different prevalence from different parts of world, our sample collection has the highest percentage so far. The repeatability showed that 1.7% (6/347) and 18.4% (64/347) were reported differently in the intra- and inter- batch analysis, respectively, which demonstrated that the threshold of this method could be further optimized to increase the sensitivity of MRSA detection. Overall, Bruker? MALDI Biotyper can detect S. aureus isolates with a quite high specificity and expedite the identification of MRSA isolates without using extra reagent, labor or time. The reduced turnaround time of MRSA identification is essential for appropriate therapeutic management and timely intervention for infection control.
关键词： MRSA,MALDI-TOF MS,resistant,specificity,sensitivity
更新于2025-09-11 14:15:04
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Environmental disinfection with photocatalyst as an adjunctive measure to control transmission of methicillin-resistant Staphylococcus aureus: a prospective cohort study in a high-incidence setting
摘要： Background: Environmental disinfection with continuously antimicrobial surfaces could offer superior control of surface bioburden. We sought to decide the efficacy of photocatalyst antimicrobial coating in reducing methicillin-resistant Staphylococcus aureus (MRSA) acquisition in high incidence setting. Methods: We performed prospective cohort study involving patients hospitalized in medical intensive care unit. A titanium dioxide-based photocatalyst was coated on high touch surfaces and walls. Five months of pre-intervention data were compared with five months of post-intervention data. The incidence rates of multidrug-resistant organism acquisition and the rates of hospital-acquired blood stream infection, pneumonia, urinary tract infection, and Clostridium difficile–associated diseases were compared using Cox proportional hazards regression analysis. Results: In total, 621 patients were included. There was significant decrease in MRSA acquisition rate after photocatalyst coating (hazard ratio, 0.37; 95% confidence interval, 0.14–0.99; p = 0.04). However, clinical identification of vancomycin-resistant Enterococcus spp. and multidrug-resistant Acinetobacter baumannii did not decrease significantly. The hazard of contracting hospital-acquired pneumonia during the intervention period compared to baseline period was 0.46 (95% confidence interval, 0.23–0.94; p = 0.03). Conclusions: In conclusion, MRSA rate was significantly reduced after photocatalyst coating. We provide evidence that photocatalyst disinfection can be an adjunctive measure to control MRSA acquisition in high-incidence settings. Trial registration: ISRCTN Registry (ISRCTN31972004). Registered retrospectively on November 19, 2018.
关键词： Environmental disinfection,Hospital-acquired infection,MRSA,Photocatalyst
更新于2025-09-09 09:28:46