scholarly journals Antibiofilm and antivirulence potential of silver nanoparticles against multidrug-resistant Acinetobacter baumannii

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Helal F. Hetta ◽  
Israa M. S. Al-Kadmy ◽  
Saba Saadoon Khazaal ◽  
Suhad Abbas ◽  
Ahmed Suhail ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Acinetobacter Baumannii ◽  
Biofilm Formation ◽  
Microtiter Plate ◽  
Diffusion Method ◽  
Resistance Pattern ◽  
Infection Model ◽  
The Impact

AbstractWe aimed to isolate Acinetobacter baumannii (A. baumannii) from wound infections, determine their resistance and virulence profile, and assess the impact of Silver nanoparticles (AgNPs) on the bacterial growth, virulence and biofilm-related gene expression. AgNPs were synthesized and characterized using TEM, XRD and FTIR spectroscopy. A. baumannii (n = 200) were isolated and identified. Resistance pattern was determined and virulence genes (afa/draBC, cnf1, cnf2, csgA, cvaC, fimH, fyuA, ibeA, iutA, kpsMT II, PAI, papC, PapG II, III, sfa/focDE and traT) were screened using PCR. Biofilm formation was evaluated using Microtiter plate method. Then, the antimicrobial activity of AgNPs was evaluated by the well-diffusion method, growth kinetics and MIC determination. Inhibition of biofilm formation and the ability to disperse biofilms in exposure to AgNPs were evaluated. The effect of AgNPs on the expression of virulence and biofilm-related genes (bap, OmpA, abaI, csuA/B, A1S_2091, A1S_1510, A1S_0690, A1S_0114) were estimated using QRT-PCR. In vitro infection model for analyzing the antibacterial activity of AgNPs was done using a co-culture infection model of A. baumannii with human fibroblast skin cell line HFF-1 or Vero cell lines. A. baumannii had high level of resistance to antibiotics. Most of the isolates harbored the fimH, afa/draBC, cnf1, csgA and cnf2, and the majority of A. baumannii produced strong biofilms. AgNPs inhibited the growth of A. baumannii efficiently with MIC ranging from 4 to 25 µg/ml. A. baumannii showed a reduced growth rate in the presence of AgNPs. The inhibitory activity and the anti-biofilm activity of AgNPs were more pronounced against the weak biofilm producers. Moreover, AgNPs decreased the expression of kpsMII , afa/draBC,bap, OmpA, and csuA/B genes. The in vitro infection model revealed a significant antibacterial activity of AgNPs against extracellular and intracellular A. baumannii. AgNPs highly interrupted bacterial multiplication and biofilm formation. AgNPs downregulated the transcription level of important virulence and biofilm-related genes. Our findings provide an additional step towards understanding the mechanisms by which sliver nanoparticles interfere with the microbial spread and persistence.

Evaluation of the Role of Staphylococci in the Pathomechanism of Conjunctivitis

2021 ◽  
Author(s):  
Ewa Jasińska ◽  
Agnieszka Bogut ◽  
Agnieszka Magryś ◽  
Alina Olender
Keyword(s):  
Antibiotic Resistance ◽  
Epithelial Cells ◽  
Biofilm Formation ◽  
Methicillin Resistance ◽  
Microtiter Plate ◽  
Host Cells ◽  
Diffusion Method ◽  
Microtiter Plate Assay ◽  
Low Prevalence

Abstract Purpose: Determination of the association between ica genes and phenotypic biofilm formation in staphylococcal isolates involved in conjunctivitis, their antibiotic resistance as well as detection of selected virulence characteristics: adhesion to epithelial cells and in vitro cytotoxicity.Methods: The study included 26 Staphylococcus aureus (SA) and 26 Staphylococcus epidermidis (SE) isolates. The presence of icaAD genes and ica operon was determined by the PCR assay. Phenotypic biofilm formation was verified using the microtiter plate assay. Antibiotic resistance was performed using the disc diffusion method. Staphylococcal ability to attach to host cells was assessed by flow cytometry. Cytotoxicity on epithelial cells was evaluated by LDH assay.Results: The ica genes were detected in 26.9% of SE and in 42.3% of SA isolates. Only 15.3% of isolates (SE) were positive for both the icaAD and the ica operon. Phenotypically, 19.2% of SE isolates were strong biofilm producers, among which three were both icaAD- and ica operon-positive. 26.9% of SA isolates were strong biofilm producers. Methicillin resistance (MR) was detected in 34.6% of SE and 26.9% of SA isolates. 75% of MR isolates were multidrug resistant. SA isolates adhered to host cells more extensively than SE. SA isolates released higher level of LDH than SE.Conclusions: Adherence abilities were commonly observed in staphylococci associated with conjunctivitis. However, low prevalence of isolates positive for a complete and functional ica locus and low prevalence of strong biofilm producers was detected. SA adhered to a greater extent to eukaryotic cells than SE and were more cytotoxic.

scholarly journals Correlation of biofilm formation and antibiotic resistance among clinical and soil isolates of Acinetobacter baumannii in Iraq

2019 ◽  
pp. 1-10 ◽  
Author(s):  
Pakhshan A. Hassan ◽  
Adel K. Khider
Keyword(s):  
Acinetobacter Baumannii ◽  
Congo Red ◽  
Biofilm Formation ◽  
Opportunistic Pathogen ◽  
Microtiter Plate ◽  
Test Tube ◽  
Clinical Isolates ◽  
Diffusion Method ◽  
Biochemical Tests ◽  
Disk Diffusion Method

Acinetobacter baumannii is an opportunistic pathogen that is reported as a major cause of nosocomial infections. The aim of this study was to investigate the biofilm formation by A. baumannii clinical and soil isolates, to display their susceptibility to 11 antibiotics and to study a possible relationship between formation of biofilm and multidrug resistance. During 8 months period, from June 2016 to January 2017, a total of 52 clinical and 22 soil isolates of A. baumannii were collected and identified through conventional phenotypic, chromo agar, biochemical tests, API 20E system, and confirmed genotypically by PCR for blaOXA-51-like gene. Antibiotic susceptibility of isolates was determined by standard disk diffusion method according to Clinical and Laboratory Standard Institute. The biofilm formation was studied using Congo red agar, test tube, and microtiter plate methods. The clinical isolates were 100% resistance to ciprofloxacin, ceftazidime, piperacillin, 96.15% to gentamicin, 96.15% to imipenem, 92.31% to meropenem, and 78.85% to amikacin. The soil A. baumannii isolates were 100% sensitive to imipenem, meropenem, and gentamicin, and 90.1% to ciprofloxacin. All A. baumannii isolates (clinical and soil) were susceptible to polymyxin B. The percentage of biofilm formation in Congo red agar, test tube, and microtiter plate assays was 10.81%, 63.51%, and 86.48%, respectively. More robust biofilm former population was mainly among non-MDR isolates. Isolates with a higher level of resistance tended to form weaker biofilms. The soil isolates exhibited less resistance to antibiotics than clinical isolates. However, the soil isolates produce stronger biofilms than clinical isolates.

scholarly journals Enhanced antibacterial activity through silver nanoparticles deposited onto carboxylated graphene oxide surface

2021 ◽  
Author(s):  
Arturo Barjola ◽  
María Ángeles Tormo ◽  
Oscar Sahuquillo ◽  
Patricia Bernabé ◽  
José Manuel Pérez ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Graphene Oxide ◽  
Biofilm Formation ◽  
Material Surface ◽  
Oxide Surface ◽  
Main Role ◽  
Carboxylic Groups ◽  
Average Size

Abstract The strong bactericidal action of silver nanoparticles (AgNPs) is usually limited for their degree of aggregation. Deposition of AgNPs onto a graphene oxide (GO) surface to generate GO-Ag hybrids has been shown to be an effective method to control these aggregation problems. In this sense, a novel carboxylated graphene oxide-silver nanoparticle (GOCOOH-Ag) material has been synthesized and their antibacterial and biofilm formation inhibition have been studied.AgNPs decorating the GOCOOH surface achieved an average size of 6.74±0.25 nm, which was smaller than those of AgNPs deposited onto the GO surface. In addition, better distribution of AgNPs was obtained using carboxylated material. It is important to highlight the main role of the carboxylic groups in the nucleation and growth of the AgNPs that decorate the GO-based material surface.In vitro antibacterial activity and antibiofilm-forming action were tested against Gram-positive (Staphylococcus aureus and Staphylococcus epidermidis) and Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli). Both GO-Ag and GOCOOH-Ag reduced the bacterial growth, analyzed by time-kill curves. However, the minimum inhibitory concentration and the minimum bactericidal concentration of GOCOOH-Ag were lower than those of GO-Ag for all strains studied, indicating that GOCOOH-Ag has better antibacterial activity. In addition, both nanomaterials prevent biofilm-formation, with a higher reduction of biofilm mass and cell viability in the presence of GOCOOH-Ag. The carboxylation functionalization in GO-based materials can be applied to improve the bactericidal and antibiofilm-forming action of the AgNPs.

scholarly journals Antibacterial ativity of biosynthesized silver nanoparticles against Pseudomonas aeruginosa in vitro

2017 ◽  
Vol 41 (1) ◽  
pp. 60-65
Author(s):  
Ahmad N. A. Salih ◽  
Mohammad J. Eesa
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pseudomonas Aeruginosa ◽  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Silver Sulfadiazine ◽  
Diffusion Method ◽  
Olive Leaves ◽  
Scanning Electron

     This study was conducted for the synthesis of silver nanoparticles by using olive leaves aqueous extract and evaluate its antibacterial activity against Pseudomonas aeruginosa in vitro. The synthesis and characterization of silver nanoparticles was confirmed by Ultra Violet Visible – spectrophotometer and Scanning Electron Microscopy. Well diffusion method was used to show the antibacterial action of silver nanoparticles against Pseudomonas aeruginosa in vitro in comparison with standard antibacterial silver sulfadiazine by using different concentrations of each agent ranged from 12.5-200 μg/ml. The results of this study showed it possible to produce silver nanoparticles in eco-friendly and easy process and UV-Visible absorption spectra of the silver nanoparticles revealed maximum absorbance at 420 and 430 nm. The Scanning Electron Microscopy analysis demonstrated the mean of the silver particles diameter was 26 nm. The antibacterial findings of the synthesized silver nanoparticles against Pseudomonas aeruginosa in vitro showed that the silver nanoparticles were more effective than silver sulfadiazine against Pseudomonas aeruginosa. It could be concluded that olive leaves extract can be used effectively in the production of silver nanoparticles and these synthesized nanoparticles had considerable antibacterial activity against Pseudomonas aeruginosa in vitro.                                                        

scholarly journals In vitro Anti-Bacterial Activity of Oral Herbal Medicines Assessed by Agar Well Diffusion and Broth Micro-Dilution Methods

2016 ◽  
pp. 15-19
Author(s):  
Kamal Kanta Das ◽  
Mrityunjoy Acharjee ◽  
Rashed Noor
Keyword(s):  
Antibacterial Activity ◽  
Herbal Medicines ◽  
Multidrug Resistant ◽  
Diffusion Method ◽  
Resistance Pattern ◽  
Drug Resistance Pattern ◽  
Viable Bacteria ◽  
Agar Well Diffusion Assay ◽  
Staphylococcus Spp

Recently antibacterial activity of ten commonly available oral herbal medicines has tested in our laboratory. Current investigation further endeavoured to compute the microbial propagation in six more oral herbal medicines, including the drug resistance pattern of the microbial isolates, and antibacterial potential of the medicines by employing both agar well diffusion method and broth micro-dilution procedure to determine the minimum inhibitory concentration (MIC). Among the 30 samples of 6 categories studied, the total viable bacteria were found within the range of 104-107 cfu/ml, while the presence of fungi was noticed only in 3 samples up to 105 cfu/ml. All samples were found to be contaminated with Staphylococcus spp., 2 samples with Escherichia coli and 1 sample was found to be contaminated with Klebsiella spp. Most of the isolates showed resistance against commonly used 13 antibiotics; 80% isolates were found to be multidrug-resistant (MDR). All samples exhibited antibacterial activity with their MIC values up to 55 mg/ml. However, using the agar well diffusion assay, antibacterial activity was detected only in case of only 1 sample.Bangladesh J Microbiol, Volume 32, Number 1-2,June-Dec 2015, pp 15-19

scholarly journals Exceptional antibacterial and cytotoxic potency of monodisperse greener AgNPs prepared under optimized pH and temperature

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Muhammad Riaz ◽  
Vishal Mutreja ◽  
Shweta Sareen ◽  
Bashir Ahmad ◽  
Muhammad Faheem ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Reduction Rate ◽  
Spherical Shape ◽  
Diffusion Method ◽  
Gram Negative ◽  
Stabilizing Agents ◽  
Close Relationship ◽  
The Impact ◽  
Agar Well Diffusion Method

AbstractIn the present work, silver nanoparticles were prepared by using the extract of Camellia Sinensis. The extract contains phytochemicals which are mainly polyphenols acting as the natural reducing and stabilizing agents leading to the formation of uniformly dispersed and stabilized silver nanoparticles. The synthesis of silver nanoparticles was significantly influenced by the impact of the pH, as well as temperature conditions. It was found that at pH 5 and 25 °C, nanoparticles of different morphologies (spherical, polygonal, capsule) and sizes were formed. However, with the increase in temperature from 25 °C to 65 °C but at the same pH, these particles started attaining the spherical shape of different sizes owing to an increase in the reduction rate. Furthermore, for the reaction of the mixture at 65 °C, an increase in pH from 5 to 11 led to an increase in the monodispersity of spherically shaped nanoparticles, attributed to the hydroxide ions facilitated reduction. The prepared nanoparticles were investigated for their antibacterial activity using Nathan’s Agar Well-Diffusion method. It was found that AgNPs prepared at pH 9 and 65 °C demonstrated strong antibacterial activity against gram-negative Escherichia coli in contrast to gram-positive Staphylococcus aureus. In reference to the cytotoxic potency, the prepared AgNPs showed clear cytotoxicity for HeLa cells and showcased a close relationship between activity and concentration as evidenced by the decrease in the percentage (100 to 30%) of metabolically active cells up to 25 µM–75 µM concentration of silver nanoparticles.

scholarly journals In-vitro Antibacterial Activity of Novel Nanostructured Composites Based on Forsterite and Silver Nanoparticles

2020 ◽  
Vol 71 (1) ◽  
pp. 13-21
Author(s):  
Alexandra Avram ◽  
Maria Gorea ◽  
Sorin Rapuntean ◽  
Aurora Mocanu ◽  
Gertrud Alexandra Paltinean ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Sol Gel ◽  
Trisodium Citrate ◽  
Inhibitory Effect ◽  
Aureus Strain ◽  
Diffusion Method ◽  
Zones Of Inhibition

There is a continuous need for discovering new nanomaterials with antibacterial activity against various pathogens, like Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). This study was performed to assess the antimicrobial activity of two novel nanostructured forsterites, both in the absence and the presence of silver nanoparticles (AgNPs). The two nano forsterites (FS) were prepared by advanced sol-gel (FSsg) and precipitation (FSpp) methods. Preparation of colloidal AgNPs systems was realized by using the precursor, AgNO3, and the trisodium citrate and tanic acid assuring the formation and stabilization of AgNPs. The characterization of nano forsterite powders was carried out using complementary physical methods: XRD, SEM, and AFM. The AgNPs were characterized by UV-Vis spectra, STEM and AFM imaging. The antimicrobial activity was studied by the agar well diffusion method both in the FS native state, as FSsg and FSpp, and in their mixture with silver nanoparticles (AgNPs). The inhibitory effect of synthesized forsterites, FSsg and FSpp, particularly variants with AgNPs was found only on the S. aureus strain, the zones of inhibition being between 8 and 10 mm, and more intensely expressed in the FSpp-AgNPs dispersions. These findings open new orthopedic applications of these systems, particularly for antimicrobial coated metallic implants.

scholarly journals Hyaluronan Modulation Impacts Staphylococcus aureus Biofilm Infection

2016 ◽  
Vol 84 (6) ◽  
pp. 1917-1929 ◽  
Author(s):  
Carolyn B. Ibberson ◽  
Corey P. Parlet ◽  
Jakub Kwiecinski ◽  
Heidi A. Crosby ◽  
David K. Meyerholz ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Biofilm Formation ◽  
Infection Model ◽  
Wild Type ◽  
Content Type ◽  
Joint Infections ◽  
The Impact ◽  
Biofilm Infection ◽  
Biofilm Matrix

Staphylococcus aureusis a leading cause of chronic biofilm infections. Hyaluronic acid (HA) is a large glycosaminoglycan abundant in mammalian tissues that has been shown to enhance biofilm formation in multiple Gram-positive pathogens. We observed that HA accumulated in anS. aureusbiofilm infection using a murine implant-associated infection model and that HA levels increased in a mutant strain lacking hyaluronidase (HysA).S. aureussecretes HysA in order to cleave HA during infection. Throughin vitrobiofilm studies with HA, thehysAmutant was found to accumulate increased biofilm biomass compared to the wild type, and confocal microscopy showed that HA is incorporated into the biofilm matrix. Exogenous addition of purified HysA enzyme dispersed HA-containing biofilms, while catalytically inactive enzyme had no impact. Additionally, induction ofhysAexpression prevented biofilm formation and also dispersed an established biofilm in the presence of HA. These observations were corroborated in the implant model, where there was decreased dissemination from anhysAmutant biofilm infection compared to theS. aureuswild type. Histopathology demonstrated that infection with anhysAmutant caused significantly reduced distribution of tissue inflammation compared to wild-type infection. To extend these studies, the impact of HA andS. aureusHysA on biofilm-like aggregates found in joint infections was examined. We found that HA contributes to the formation of synovial fluid aggregates, and HysA can disrupt aggregate formation. Taken together, these studies demonstrate that HA is a relevant component of theS. aureusbiofilm matrix and HysA is important for dissemination from a biofilm infection.

scholarly journals Biofilm Formation and blaOXA Genes Detection Among Acinetobacter baumannii from Clinical Isolates in a Tertiary Care Kirtipur Hospital, Nepal

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Upasana Ghimire ◽  
Rupesh Kandel ◽  
Mary Neupane ◽  
Sanjit Shrestha ◽  
Sudeep K C ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Biofilm Formation ◽  
Tertiary Care ◽  
Carbapenem Resistance ◽  
Diffusion Method ◽  
Clinical Samples ◽  
Resistance Pattern ◽  
Clinical Settings ◽  
Drug Resistance Pattern ◽  
Acinetobacter Spp

(1) Background: Acinetobacter baumannii has emerged as a leading cause of nosocomial infections as they are capable of evolving resistance to various classes of antibiotics. The ability of A. baumannii to form biofilm might also be associated with increased antibiotic resistance and hence treatment failure. This study was carried to associate the biofilm formation with the drug resistance pattern of A. baumannii and to detect blaOXA-23, blaOXA-24, and blaOXA-51 from carbapenem resistance isolates. (2) Methods: Among different clinical samples, a total of 19 Acinetobacter spp. were identified with conventional microbiological procedures. The biofilm production was determined by a quantitative adherence assay. The antimicrobial susceptibility test was carried out by the Kirby-Bauer disc diffusion method, carbapenemase production detection was confirmed by Modified Hodge Test. And target resistant genes were detected by polymerase chain reaction. (3) Results: Out of 90 clinical specimens, 64.44% (58/90) showed bacterial growth. Whereas, 32.75% (19/58) isolates were identified as A. baumannii. Among all A. baumannii isolates, 84.21% (16/19) were multidrug-resistance and 63.16% (12/19) carbapenem resistance phenotypically. blaOXA-51 was detected in all the isolates and blaOXA-23 was detected only in 63.16% (12/19) isolates. However, blaOXA-24 was not detected in any of the isolates. Among A. baumannii, 89.47% (17/19) isolates produced biofilm with 47.37% (9/19) strong biofilm producers. (4) Conclusions: In the majority of MDR A. baumannii, blaOXA-51 and blaOXA-23 were detected as the determinant factor for carbapenem resistance having a direct relation with biofilm formation. This study provided a valuable clue for the management of A. baumannii infections in clinical settings.  

scholarly journals Synthesis of Chitosan Stabilized Silver Nanoparticles and Evaluation of the in vitro Antibacterial Activity Against Xanthomonas oryzae pv. oryzae Causing Blight Disease of Rice

2021 ◽  
Author(s):  
Le Thi Hien ◽  
Nguyen Thi Phuong Hue ◽  
Le Trong Duc ◽  
Vu Thi Huyen ◽  
Le Thi Van ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Silver Nitrate ◽  
Bacterial Blight ◽  
Xanthomonas Oryzae ◽  
Diffusion Method ◽  
Colloidal Systems ◽  
Potential Measurement ◽  
In Vitro Antibacterial Activity

Bacterial blight is one of the most devastating rice diseases that cause huge economic loss worldwide. The cause of rice blight is Gram negative bacteria Xanthomonas oryzae pv. oryzae (X. oryzae pv. Oryzae). Since both silver nanoparticles and chitosan have antibacterial, antifungal and growth-stimulating effect, this work has focused on synthesizing chitosan stabilized silver nanoparticles (AgCSs) with small sizes and in vitro evaluating antibacterial activity against X. oryzae pv. oryzae bacteria. AgCSs were chemically synthesized by reducing silver nitrate by borohydride sodium in the presence of chitosan with optimization of the concentration of the reactants. AgCSs were characterized by UV/vis absorption spectra, field emission scanning electronic microscopy (FESEM), ImageJ software, zeta potential measurement, Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction. AgCSs have spherical configuration and narrow size distributions with different average sizes from 15 nm to 25 nm depending on the initial concentration of silver nitrate. All AgCSs colloidal systems were stable and exhibited no tendency for coagulation more than 5 months. It was the first time that chitosan-stabilized silver nanoparticles were assessed the in vitro antibacterial activity against bacterial blight VXO_281 strain. The disc diffusion method demonstrated that the smallest size silver nanoparticles (AgCS1) showed high antibacterial effect against the X. oryzae pv. oryzae VXO_281 strain with a concentration of more than 5 µg/mL and the inhibition zone was dose-dependent. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of AgCS1 against X. oryzae pv. oryzae VXO_281 were 2.5 µg/mL and 20 µg/mL, respectively.

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