Comparative Assessment of Bacteriophage and Antibiotic Activity against Multidrug-Resistant Staphylococcus aureus Biofilms.

Problems connected with biofilm-related infections and antibiotic resistance necessitate the investigation and development of novel treatment strategies. Given their unique characteristics, one of the most promising alternatives to conventional antibiotics are bacteriophages. In the in vitro and in vivo larva model study, we demonstrate that phages vB_SauM-A, vB_SauM-C, and vB_SauM-D are effective antibiofilm agents. The exposure of biofilm to phages vB_SauM-A and vB_SauM-D led to 2-3 log reductions in the colony-forming unit number in most of the multidrug-resistant S. aureus strains. It was found that phage application reduced the formed biofilms independently of the used titer. Moreover, the study demonstrated that bacteriophages are more efficient in biofilm biomass removal and reduction in staphylococci count when compared to the antibiotics used. The scanning electron microscopy analysis results are in line with colony forming unit (CFU) counting but not entirely consistent with crystal violet (CV) staining. Additionally, phages vB_SauM-A, vB_SauM-C, and vB_SauM-D can significantly increase the survival rate and extend the survival time of Galleria mellonella larvae.

Modelling the growth of Staphylococcus aureus on cooked broccoli under isothermal conditions.

In this study, we developed predictive models describing the growth of Staphylococcus aureus on cooked broccoli florets. A pool of 3.5 log CFU/g of five S. aureus strains were inoculated on 10 g broccoli portions. The samples were then stored at 10, 20, 30 and 37 °C, and colonies were enumerated at different time intervals. Baranyi and Roberts model was fitted to the data using a Bayesian Adaptive Markov Chain Monte Carlo for estimation of the growth parameters. S. aureus showed low growth at 10 °C on broccoli samples and at 20-37 °C interval, Baranyi and Roberts model fitted well to the experimental data (R2>0.97). Estimated growth parameters were correlated with the possibility of toxin production and indicate the potential presence of these biological hazards on contaminated broccoli after heat treatment. Additionally, linear regression was performed for growth rate as storage temperature function. This secondary model followed a linear tendency with R2=0.997 and was compared with two tertiary models (ComBase Predictor and Pathogen Modeling Program) and literature data, demonstrating similar growth rate values of both. These results can be helpful for food services and managers to establish food safety standards for S. aureus growth on cooked broccoli.

In vitroassessment of green polyhydroxybutyrate/chitosan blend loaded with kaempferol nanocrystals as a potential dressing for infected wounds.

Despite the major medical advancements in recent decades, treating infected wounds successfully remains a challenge. In this research, a functional blend of Polyhydroxybutyrate (PHB) and Chitosan (Cs) was developed for wound infection mitigation with tailored biological and physicochemical properties. Water insoluble kaempferol (KPF) was pre-formulated to water soluble KPF nanocrystals (KPF-NCs) with fine particle size of 145 ± 11 nm, and high colloidal stability (-31 ± 0.4 mV) to improve its drug transdermal delivery. PHB-Cs-KPF-NCs (1:2 ratio) film owned the best physical properties in terms of high breathability, thermal stability and mechanical strength (33 ± 1 MPa). Besides, XRD and FTIR findings indicated the interaction between Cs, PHB and KPF, reducing the film crystallinity. The scanning electron microscopy of the film displayed a highly interconnected porous morphology. KPF-NCs were integrated in PHB-Cs matrix with a marked encapsulation efficiency of 96.6%. The enhanced drug-loading film showed a sustain release pattern of KPF-NCs over 48 h. Interestingly, the developed blend possessed an impressive blood clotting capacity within 20 min. Furthermore, we presented a new naturally-sourced mixture of Cs+KPF-NCs with powerful antibacterial effects against MDRStaphylococcus aureusandAcentibacter baumanniiat very low concentrations. The membrane evidenced a remarkable antibacterial naturein vitrowith almost 100% cell viability reduction against the study strains after 48 h. By virtue of these advantages, this green blend is highly proposed for optimal wound care.

Green synthesis and characterization of silver nanoparticles from Moringa oleifera flower and assessment of antimicrobial and sensing properties.

The present study aimed to explore the biosynthesis and characterization of silver nanoparticles (AgNPs) from Moringa oleifera flower (MOF) extract and its antimicrobial and sensing properties. The prepared AgNPs were characterized by Transmission Electron Microscopy (TEM), UV-visible spectral analysis (UV-vis), X-Ray Diffraction (X-RD), Energy Dispersive Spectroscopy (EDS), and Fourier Infra-Red Spectroscopy (FTIR) respectively. Antimicrobial and sensing properties of the prepared nanoparticles were also determined. Face-Centered Cubic (FCC) lattice of the AgNPs was observed in X-RD pattern. FTIR measurement evidenced the band pattern at 686, 1653, 2062 and 3456 cm-1 proved the presence of proteins and phenolic components in MOF responsible for reduction. TEM analysis indicated the formation of monodispersed spherical particles with 8 nm. UV-vis of the prepared AgNPs authenticated the surface plasmon resonance (SPR) at 429 nm and stable for six months. AgNPs have produced highest zone of inhibition (ZOI) of 17 mm and 29 mm against Klebsiella pneumoniae and Staphylococcus aureus respectively. In addition, the AgNPs effectively detected the presence of Copper ions from 1 mM to 12 mM concentrations. Copper sensitivity of these biosynthesized nanoparticles was carried out by optical sensor based SPR. Thus the obtained antimicrobial and optical properties, suggested the use of obtained AgNPs in water purification.

Fitness costs associated with carriage of a large staphylococcal plasmid are reduced by subinhibitory concentrations of antiseptics.

Staphylococcus aureus carries a collection of mobile genetic elements that often harbor virulence and antimicrobial resistance genes. Since the introduction of antibiotics, plasmids have become a major genetic element responsible for the distribution of antimicrobial resistance. Under antimicrobial selection, resistance plasmids are maintained within bacterial populations as a means to ensure survival. However, in the absence of selection, large plasmids can be lost due to the fitness costs associated with harboring these genetic elements. pC02 is a previously identified multidrug resistance, conjugative plasmid that is found in S. aureus. In addition to antibiotic resistance, pC02 also carries genes known to be associated with antiseptic resistance. Among these, we previously characterized the contribution of qacA to pC02 mediated reduced chlorhexidine susceptibility. Herein, we demonstrate that pC02 also mediates triclosan resistance, likely due to the presence of fabI, a known triclosan resistance gene. Moreover, we demonstrate that conjugative transfer of pC02 increases triclosan resistance in recipient cells. Competition assays demonstrated a fitness cost associated with carriage of the large pC02 plasmid. However, subinhibitory concentrations of either chlorhexidine or triclosan abrogated this fitness cost. Given the widespread use of these antiseptics, both of which accumulate in wastewater and other environmental reservoirs, indiscriminate use of antiseptics likely imposes a constant selective pressure that promotes maintenance of antimicrobial resistance factors within S. aureus.

The odour assessment of thyme essential oils in electrospun fibre mat with a virtual sensor array data and its relation to antibacterial activity.

Aims: The ability of a single-sensor gas diagnosis device (SSGDD) as a virtual sensor array data to appraise thyme essential oils (TEO) based on its quantitatively release rate from nanofibres was aimed.Methods: To form nylon 6 fragrant electrospun nanofibre, TEO was added as a natural antibacterial substance under homogeniser to make a stable emulsion.Results: The optimised nanofibre inactivated against Escherichia Coli and Staphylococcus Aureus bacteria up to >75% at once and to > 41.9% over 2-weeks period. Moreover, large differences in sensor responses to samples with experimental variables (percent TEO and storage time) and different odour intensity exist which correctly classified by discriminant function analysis.Conclusions: Odour intensity as an accessible incubator evinces the nanofibres efficiency which correlated to the antibacterial activity. With applying SSGDD technique as a quantified subjective solution, carefully odour assessment is possible and prepared mats could be demonstrated as a face-masks' promising candidate.

Assessment of the Efficacy of Tributylammonium Alginate Surface-Modified Polyurethane as an Antibacterial Elastomeric Wound Dressing for both Noninfected and Infected Full-Thickness Wounds.

Risk factors of nonhealing wounds include persistent bacterial infections and rapid onset of dehydration; therefore, wound dressings should be used to accelerate the healing process by helping to disinfect the wound bed and provide moisture. Herein, we introduce a transparent tributylammonium alginate surface-modified cationic polyurethane (CPU) wound dressing, which is appropriate for full-thickness wounds. We studied the physicochemical properties of the dressing using Fourier transform infrared, 1H NMR, and 13C NMR spectroscopies and scanning electron microscopy, energy-dispersive X-ray, and thermomechanical analyses. The surface-modified polyurethane demonstrated improved hydrophilicity and tensile Young's modulus that approximated natural skin, which was in the range of 1.5-3 MPa. Cell viability and in vitro wound closure, assessed by MTS and the scratch assay, confirmed that the dressing was cytocompatible and possessed fibroblast migratory-promoting activity. The surface-modified CPU had up to 100% antibacterial activity against Staphylococcus aureus and Escherichia coli as Gram-positive and Gram-negative bacteria, respectively. In vivo assessments of both noninfected and infected wounds revealed that the surface-modified CPU dressing resulted in a faster healing rate because it reduced the persistent inflammatory phase, enhanced collagen deposition, and improved the formation of mature blood vessels when compared with CPU and commercial Tegaderm wound dressing.

Assessment of Phenotype Microarray plates for rapid and high-throughput analysis of collateral sensitivity networks.

The crisis of antimicrobial resistance is driving research into the phenomenon of collateral sensitivity. Sometimes, when a bacterium evolves resistance to one antimicrobial, it becomes sensitive to others. In this study, we have investigated the utility of Phenotype Microarray (PM) plates for identifying collateral sensitivities with unprecedented throughput. We assessed the relative resistance/sensitivity phenotypes of nine strains of Staphylococcus aureus (two laboratory strains and seven clinical isolates) towards the 72 antimicrobials contained in three PM plates. In general, the PM plates reported on resistance and sensitivity with a high degree of reproducibility. However, a rigorous comparison of PM growth phenotypes with minimum inhibitory concentration (MIC) measurements revealed a trade-off between throughput and accuracy. Small differences in PM growth phenotype did not necessarily correlate with changes in MIC. Thus, we conclude that PM plates are useful for the rapid and high-throughput assessment of large changes in collateral sensitivity phenotypes during the evolution of antimicrobial resistance, but more subtle examples of cross-resistance or collateral sensitivity cannot be identified reliably using this approach.

Prospective evaluation of rapid antimicrobial susceptibility testing by disk diffusion on Mueller-Hinton rapid-SIR directly on blood cultures.

BACKGROUND: With the worldwide spread of antibiotic resistance, delivering antibiotic susceptibility test (AST) results in a timely manner represents a major challenge. In cases of sepsis, rapid AST may facilitate early optimization of empiric antibiotic therapy. Disc diffusion is a well-standardized AST method, however 16 to 24 h are required to achieve an overall AST profile according to antimicrobial societies. METHODS: In this prospective pilot study, we evaluated the performance of Mueller-Hinton-Rapid-SIR (MHR-SIR) agar after 6-8 h of incubation in comparison with standard MH agar after 16 h of incubation directly on positive blood cultures caused by Enterobacteriaceae and Staphylococcus aureus from routine clinical microbiology. A total of 133 positive blood samples including 110 Enterobacteriaceae (83%) and 23 Staphylococcus aureus (17%) were tested in parallel by two direct AST methods, each using EUCAST breakpoints. For each combination bacterium and antibiotic, we compared the categorical agreement and the correlation between the diameters obtained by MHR-SIR and by standard MH. RESULTS: Our results showed 97.7% categorical agreement for Enterobacteriaceae, with 1.4% minor errors, 0.4% major errors and 0.5% very major errors. For S. aureus, we observed 97.8% categorical agreement, 1.9% minor errors, 0.3% major errors and no very major errors. CONCLUSION: Our results showed excellent categorical agreement and correlations between diameters for MHR-SIR and standard MH methods. MHRSIR can predict the result of overall AST profile within 6-8 h with reliable results. AST is obtained on the same day the blood culture becomes positive, with a very moderate cost.

Impact of an infectious diseases specialist-led antimicrobial stewardship programmes on antibiotic use and antimicrobial resistance in a large Korean hospital.

The aim of this study was to evaluate the impact of an infectious diseases specialist (IDS)-led antimicrobial stewardship programmes (ASPs) in a large Korean hospital. An interrupted time series analysis assessing the trends in antibiotic use and antimicrobial resistance rate of major pathogens between September 2015 and August 2017 was performed in an 859-bed university-affiliated hospital in Korea. The restrictive measure for designated antibiotics led by an IDS reduced carbapenems usage by -4.57 days of therapy (DOT)/1,000 patient-days per month in general wards (GWs) (95% confidence interval [CI], -6.69 to -2.46; P < 0.001), and by -41.50 DOT/1,000 patient-days per month in intensive care units (ICUs) (95% CI, -57.91 to -25.10; P < 0.001). Similarly, glycopeptides usage decreased by -2.61 DOT/1,000 patient-days per month in GWs (95% CI, -4.43 to -0.79; P = 0.007), and -27.41 DOT/1,000 patient-days per month in ICUs (95% CI, -47.03 to -7.79; P = 0.009). Use of 3rd generation cephalosporins, beta-lactam/beta-lactamase inhibitors, and fluoroquinolones in GWs showed change comparable with that of carbapenems or glycopeptides use. Furthermore, trends of antimicrobial resistance rate of Staphylococcus aureus to gentamicin in GWs, Staphylococcus aureus to ciprofloxacin and oxacillin in ICUs, and Pseudomonas aeruginosa to imipenem in ICUs decreased in slope in the intervention period. The in-hospital mortality rate per 1,000 patient-days among ICU patients remained stable between the pre-intervention and intervention periods. In conclusion, an IDS-led ASPs could enact a meaningful reduction in antibiotic use, and a decrease in antibiotic resistance rate, without changing mortality rates in a large Korean hospital.

Identification and characterisation of Staphylococcus aureus on low cost screen printed carbon electrodes using impedance spectroscopy.

Staphylococcus aureus infections are a cause of significant morbidity and mortality, in addition to representing a considerable economic burden. The aim of this study was to explore a low cost screen printed electrode as a sensor for the detection of S. aureus using impedance spectroscopy. S. aureus was incubated in chambers containing the electrodes and the results analysed using a novel normalisation approach. These results show that it is possible to detect the presence of S. aureus in LB media after 30 min incubation of a 1% growth culture, in addition to being able to see immediate cell concentration dependant changes in 0.9% NaCl. These observations imply that a number of electrochemical mechanisms cause a change in the impedance as a result of the presence of S. aureus, including adsorption to the electrode surface and the metabolism of the bacteria during growth. The study suggests that this detection approach would be useful in a number of clinical scenarios where S. aureus leads to difficult to treat infections.

Assessment of synergistic antibacterial activity of combined biosurfactants revealed by bacterial cell envelop damage.

Besides potential surface activity and some beneficial physical properties, biosurfactants express antibacterial activity. Bacterial cell membrane disrupting ability of rhamnolipid produced by Pseudomonas aeruginosa C2 and a lipopeptide type biosurfactant, BS15 produced by Bacillus stratosphericus A15 was examined against Staphylococcus aureus ATCC 25923 and Escherichia coli K8813. Broth dilution technique was followed to examine minimum inhibitory concentration (MIC) of both the biosurfactants. The combined effect of rhamnolipid and BS15 against S. aureus and E. coli showed synergistic activity by expressing fractional inhibitory concentration (FIC) index of 0.43 and 0.5. Survival curve of both the bacteria showed bactericidal activity after treating with biosurfactants at their MIC obtained from FIC index study as it killed >90% of initial population. The lesser value of MIC than minimum bactericidal concentration (MBC) of the biosurfactants also supported their bactericidal activity against both the bacteria. Membrane permeability against both the bacteria was supported by amplifying protein release, increasing of cell surface hydrophobicity, withholding capacity of crystal violet dye and leakage of intracellular materials. Finally cell membrane disruption was confirmed by scanning electron microscopy (SEM). All these experiments expressed synergism and effective bactericidal activity of the combination of rhamnolipid and BS15 by enhancing the bacterial cell membrane permeability. Such effect of the combination of rhamnolipid and BS15 could make them promising alternatives to traditional antibiotic in near future.

Survivability and fitness cost of heterogeneous vancomycin-intermediate Staphylococcus aureus.

The aim of this study was to observe the survivability and fitness cost of heterogeneous vancomycin-intermediate Staphylococcus aureus(hVISA) isolates. Survivability study was performed on dry cotton swab, and fitness cost was evaluated by estimating growth kinetics and generation time constant in BACTEC automated system. Total mean maximum time of recovery on primary culture was 4.1 and 7.1 weeks (P = 0.0001) for hVISA and vancomycin-sensitive S. aureus (VSSA), respectively, in dry starved condition. No significant difference between the mean value of lag phase duration (P = 0.89) was noted between hVISA and VSSA isolate in growth kinetics. However, we observed lesser generation time of hVISA isolates compared to S. aureus ATCC 29213 (P = 0.0076). This study concluded that a significant difference in generation time between VSSA and hVISA and suggests that hVISA have fitness cost compared to VSSA. However, further studies with more cases are required.

Production of Recombinant Antimicrobial Polymeric Protein Beta Casein-E 50-52 and Its Antimicrobial Synergistic Effects Assessment with Thymol.

Accelerating emergence of antimicrobial resistance among food pathogens and consumers' increasing demands for preservative-free foods are two contemporary challenging aspects within the food industry. Antimicrobial packaging and the use of natural preservatives are promising solutions. In the present study, we used beta-casein-one of the primary self-assembly proteins in milk with a high polymeric film production capability-as a fusion partner for the recombinant expression of E 50-52 antimicrobial peptide in Escherichia coli. The pET21a-BCN-E 50-52 construct was transformed to E. coli BL21 (DE3), and protein expression was induced under optimized conditions. Purified protein obtained from nickel affinity chromatography was refolded under optimized dialysis circumstances and concentrated to 1600 µg/mL fusion protein by ultrafiltration. Antimicrobial activities of recombinant BCN-E 50-52 performed against Escherichia coli, Salmonella typhimurium, Listeria monocytogenes, Staphylococcus aureus, Aspergillus flavus, and Candida albicans. Subsequently, the synergistic effects of BCN-E 50-52 and thymol were assayed. Results of checkerboard tests showed strong synergistic activity between two compounds. Time-kill and growth kinetic studies indicated a sharp reduction of cell viability during the first period of exposure, and SEM (scanning electron microscope) results validated the severe destructive effects of BCN E 50-52 and thymol in combination on bacterial cells.

Solidification and Biotoxicity Assessment of Thermally Treated Municipal Solid Waste Incineration (MSWI) Fly Ash.

In the present work, thermal treatment was used to stabilize municipal solid waste incineration (MSWI) fly ash, which was considered hazardous waste. Toxicity characteristic leaching procedure (TCLP) results indicated that, after the thermal process, the leaching concentrations of Pb, Cu, and Zn decreased from 8.08 to 0.16 mg/L, 0.12 to 0.017 mg/L and 0.39 to 0.1 mg/L, respectively, which well met the limits in GB5085.3-2007 and GB16689-2008. Thermal treatment showed a negative effect on the leachability of Cr with concentrations increasing from 0.1 to 1.28 mg/L; nevertheless, it was still under the limitations. XRD analysis suggested that, after thermal treatments, CaO was newly generated. CaO was a main contribution to higher Cr leaching concentrations owing to the formation of Cr (VI)-compounds such as CaCrO4. SEM/EDS tests revealed that particle adhesion, agglomeration, and grain growth happened during the thermal process and thus diminished the leachability of Pb, Cu, and Zn, but these processes had no significant influence on the leaching of Cr. A microbial assay demonstrated that all thermally treated samples yet possessed strong bactericidal activity according to optical density (OD) test results. Among all samples, the OD value of raw fly ash (RFA) was lowest followed by FA700-10, FA900-10, and FA1100-10 in an increasing order, which indicated that the sequence of the biotoxicity for these samples was RFA > FA700-10 > FA900-10 > FA1100-10. This preliminary study indicated that, apart from TCLP criteria, the biotoxicity assessment was indispensable for evaluating the effect of thermal treatment for MSWI fly ash.

Digital imaging information technology for biospeckle activity assessment relative to bacteria and parasites.

This paper reports on the biospeckle processing of biological activity using a visualization scheme based upon the digital imaging information technology. Activity relative to bacterial growth in agar plates and to parasites affected by a drug is monitored via the speckle patterns generated by a coherent source incident on the microorganisms. We present experimental results to demonstrate the potential application of this methodology for following the activity in time. The digital imaging information technology is an alternative visualization enabling the study of speckle dynamics, which is correlated to the activity of bacteria and parasites. In this method, the changes in Red-Green-Blue (RGB) color component density are considered as markers of the growth of bacteria and parasites motility in presence of a drug. The RGB data was used to generate a two-dimensional surface plot allowing an analysis of color distribution on the speckle images. The proposed visualization is compared to the outcomes of the generalized differences and the temporal difference. A quantification of the activity is performed using a parameterization of the temporal difference method. The adopted digital image processing technique has been found suitable to monitor motility and morphological changes in the bacterial population over time and to detect and distinguish a short term drug action on parasites.

Assessment of the Antimicrobial Activity and the Entomocidal Potential of Bacillus thuringiensis Isolates from Algeria.

This work represents the first initiative to analyze the distribution of B. thuringiensis in Algeria and to evaluate the biological potential of the isolates. A total of 157 isolates were recovered, with at least one isolate in 94.4% of the samples. The highest Bt index was found in samples from rhizospheric soil (0.48) and from the Mediterranean area (0.44). Most isolates showed antifungal activity (98.5%), in contrast to the few that had antibacterial activity (29.9%). A high genetic diversity was made evident by the finding of many different crystal shapes and various combinations of shapes within a single isolate (in 58.4% of the isolates). Also, over 50% of the isolates harbored cry1, cry2, or cry9 genes, and 69.3% contained a vip3 gene. A good correlation between the presence of chitinase genes and antifungal activity was observed. More than half of the isolates with a broad spectrum of antifungal activity harbored both endochitinase and exochitinase genes. Interestingly, 15 isolates contained the two chitinase genes and all of the above cry family genes, with some of them harboring a vip3 gene as well. The combination of this large number of genes coding for entomopathogenic proteins suggests a putative wide range of entomotoxic activity.

Sensitive and inexpensive digital DNA analysis by microfluidic enrichment of rolling circle amplified single-molecules.

Single molecule quantification assays provide the ultimate sensitivity and precision for molecular analysis. However, most digital analysis techniques, i.e. droplet PCR, require sophisticated and expensive instrumentation for molecule compartmentalization, amplification and analysis. Rolling circle amplification (RCA) provides a simpler means for digital analysis. Nevertheless, the sensitivity of RCA assays has until now been limited by inefficient detection methods. We have developed a simple microfluidic strategy for enrichment of RCA products into a single field of view of a low magnification fluorescent sensor, enabling ultra-sensitive digital quantification of nucleic acids over a dynamic range from 1.2 aM to 190 fM. We prove the broad applicability of our analysis platform by demonstrating 5-plex detection of as little as ∼1 pg (∼300 genome copies) of pathogenic DNA with simultaneous antibiotic resistance marker detection, and the analysis of rare oncogene mutations. Our method is simpler, more cost-effective and faster than other digital analysis techniques and provides the means to implement digital analysis in any laboratory equipped with a standard fluorescent microscope.

Deep tissue biopsy vs. superficial swab culture, including microbial loading determination, in the microbiological assessment of Skin and Soft Tissue Infections (SSTIs).

Thirty-two patients affected by SSTIs including DFIs were enrolled between 2013 and 2014. Superficial swab was obtained before and after cleansing with sterile saline, and after ultrasonic debridement; deep tissue biopsy was obtained from ulcer base. Samples were diluted with 1 mL of saline, serial 10-fold dilutions to 10-6 were made and 50 µL of each dilution was plated onto appropriate media. Bacteria were identified by Vitek II system. Microbial load was expressed as CFU/mL. Statistical analysis was performed by χ2. Incidence of Gram positives was higher than Gram negatives (S. aureus and P. aeruginosa being the most frequent); concordance (same bacteria isolated before and after debridement) never exceeded 60%. Ultrasonic debridement significantly reduced bacterial load or even suppressed bacterial growth. While reliability of superficial swab is poor for microbiological diagnosis of SSTIs, swabbing after ultrasonic debridement and biopsy of the ulcer base may be equally reliable.

Cytotoxicity and antibacterial assessment of gallic acid capped gold nanoparticles.

Cytotoxicity of nanoparticles needs to be examined for their biocompatibility and suitability in biomedical applications. Gallic acid method was used for the high concentration synthesis (1mM) of gold nanoparticles (AuNPs) having narrow size-distribution at ambient temperature (25°C). Gallic acid capped AuNPs were characterized by different techniques such as, UV-vis spectroscopy, TEM, EDAX, SAED, and XPS. In-vitro stability of AuNPs with biomolecules, such as glucose and bovine serum albumin (BSA) was explored at different concertation ranges. The result reveals that AuNPs are biocompatible with normal cell line mouse embryonic fibroblast (MEF) cells up to 100ppm and cell viability can be retained more than 50% even after increasing the dose from 200 to 400ppm. Antibacterial application of AuNPs revealed that both particles and surface chemistry seems to be safer for both gram positive and gram negative bacterial cultures.