Trimethyl chitosan-capped silver nanoparticles with positive surface charge: Their catalytic activity and antibacterial spectrum including multidrug-resistant strains of Acinetobacter baumannii

2017 ◽  
Vol 155 ◽  
pp. 61-70 ◽  
Author(s):  
T.Y. Chang ◽  
C.C. Chen ◽  
K.M. Cheng ◽  
C.Y. Chin ◽  
Y.H. Chen ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Catalytic Activity ◽  
Surface Charge ◽  
Acinetobacter Baumannii ◽  
Multidrug Resistant ◽  
Trimethyl Chitosan ◽  
Positive Surface Charge ◽  
Resistant Strains ◽  
Antibacterial Spectrum

scholarly journals Trimethylchitosan-Capped Silver Nanoparticles with Positive Surface Charge: Their Catalytic Activity and Antibacterial Spectrum Including Multidrug-Resistant Strains of Acinetobacter baumannii

2017 ◽  
Author(s):  
Tein-Yao Chang ◽  
Cheng-Cheung Chen ◽  
Kuang-Ming Cheng ◽  
Chia-Yin Chin ◽  
Yu-Hao Chen ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Catalytic Activity ◽  
Surface Charge ◽  
Acinetobacter Baumannii ◽  
Multidrug Resistant ◽  
Reducing Agent ◽  
Correlation Spectroscopy ◽  
X Ray ◽  
Positive Surface Charge ◽  
Broth Microdilution Method

We report a facile route for the green synthesis of trimethylchitosan nitrate-capped silver nanoparticles (TMCN-AgNPs) with positive surface charge. In this synthesis, silver nitrate, glucose, and trimethyl chitosan nitrate (TMCN) were used as silver precursor, reducing agent, and stabilizer, respectively. The reaction was carried out in a stirred basic aqueous medium at room temperature without the use of energy-consuming or expensive equipment. We investigated the effects of the concentrations of NaOH, glucose, and TMCN on the particle size, zeta potential, and formation yield. The AgNPs were characterized by UV-visible spectroscopy, photon correlation spectroscopy, laser Doppler anemometry, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The catalytic activity of the TMCN-AgNPs was studied by the reduction of 4-nitrophenol using NaBH4 as a reducing agent. We evaluated the antibacterial effects of the TMCN-AgNPs on Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus using the broth microdilution method. The results showed that both gram-positive and gram-negative bacteria were killed by the TMCN-AgNPs at very low concentration (< 6.13 μg/mL). Moreover, the TMCN-AgNPs also showed high antibacterial activity against clinically isolated multidrug-resistant A. baumannii strains, and the minimum inhibitory concentration (MIC) was ≤ 12.25 μg/mL.

scholarly journals Silver Nanoparticles and Their Antibacterial Applications

2021 ◽  
Vol 22 (13) ◽  
pp. 7202
Author(s):  
Tamara Bruna ◽  
Francisca Maldonado-Bravo ◽  
Paul Jara ◽  
Nelson Caro
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Agents ◽  
Multidrug Resistant ◽  
Secondary Effects ◽  
Cytotoxic Effects ◽  
Factors Affecting ◽  
Gram Positive Bacteria ◽  
Resistant Strains

Silver nanoparticles (AgNPs) have been imposed as an excellent antimicrobial agent being able to combat bacteria in vitro and in vivo causing infections. The antibacterial capacity of AgNPs covers Gram-negative and Gram-positive bacteria, including multidrug resistant strains. AgNPs exhibit multiple and simultaneous mechanisms of action and in combination with antibacterial agents as organic compounds or antibiotics it has shown synergistic effect against pathogens bacteria such as Escherichia coli and Staphylococcus aureus. The characteristics of silver nanoparticles make them suitable for their application in medical and healthcare products where they may treat infections or prevent them efficiently. With the urgent need for new efficient antibacterial agents, this review aims to establish factors affecting antibacterial and cytotoxic effects of silver nanoparticles, as well as to expose the advantages of using AgNPs as new antibacterial agents in combination with antibiotic, which will reduce the dosage needed and prevent secondary effects associated to both.

scholarly journals Low concentrations of commercial alcohol hand rubs facilitate growth of and secretion of extracellular proteins by multidrug-resistant strains of Acinetobacter baumannii

2007 ◽  
Vol 56 (12) ◽  
pp. 1595-1599 ◽  
Author(s):  
Justin Edwards ◽  
Geeta Patel ◽  
David W. Wareham
Keyword(s):  
Acinetobacter Baumannii ◽  
Culture Supernatant ◽  
Multidrug Resistant ◽  
Extracellular Proteins ◽  
Nosocomial Pathogen ◽  
Emulsifying Activity ◽  
Health Care Settings ◽  
Low Concentrations ◽  
Resistant Strains ◽  
Minimal Media

Acinetobacter baumannii is increasingly recognized as an important multidrug-resistant nosocomial pathogen. Recent work has highlighted enhanced growth and heightened virulence in the presence of ethyl alcohols. As alcohol-based hand rubs (ABHRs) are extensively used in health care settings, the authors set out to determine whether the hand rubs could also influence the growth of prevalent multidrug-resistant strains circulating in UK hospitals. A significant increase in growth was observed when minimal media were supplemented with concentrations of 1 % and lower of four commercially available hand rubs. In addition, growth in ABHR-supplemented media resulted in secretion of proteins into the culture supernatant. One of these was identified as OmpA, which is recognized as having emulsifying activity, which could potentially confer enhanced pathogenicity to A. baumannii.

Efflux pump inhibitory activity of biologically synthesized silver nanoparticles against multidrug-resistant Acinetobacter baumannii clinical isolates

2020 ◽  
Vol 60 (6) ◽  
pp. 494-507 ◽  
Author(s):  
Reyhaneh Behdad ◽  
Minoo Pargol ◽  
Amir Mirzaie ◽  
Shohreh Zare Karizi ◽  
Hassan Noorbazargan ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Acinetobacter Baumannii ◽  
Inhibitory Activity ◽  
Efflux Pump ◽  
Multidrug Resistant ◽  
Clinical Isolates

Mortality Associated with Acinetobacter baumannii Complex Bacteremia among Patients with War-Related Trauma

2010 ◽  
Vol 31 (1) ◽  
pp. 92-94 ◽  
Author(s):  
Grace Kang ◽  
Joshua D. Hartzell ◽  
Robin Howard ◽  
Robert N. Wood-Morris ◽  
Mark D. Johnson ◽  
...  
Keyword(s):  
Mortality Rate ◽  
Acinetobacter Baumannii ◽  
Young Patients ◽  
Multidrug Resistant ◽  
Low Risk ◽  
Risk Of Death ◽  
High Prevalence ◽  
Acinetobacter Baumannii Complex ◽  
Resistant Strains

We investigated the mortality associated with Adnetobacter baumannii complex bacteremia among a cohort of patients hospitalized for war-related trauma. Despite a high prevalence of multidrug-resistant strains, the 30-day mortality rate was 2%. For relatively young patients with war-related trauma, A. baumannii complex bacteremia appears to be associated with a low risk of death.

scholarly journals Multidrug Resistant Acinetobacter baumannii: Risk Factors for Appearance of Imipenem Resistant Strains on Patients Formerly with Susceptible Strains

PLoS ONE ◽  
2010 ◽  
Vol 5 (4) ◽  
pp. e9947 ◽  
Author(s):  
Jung-Jr Ye ◽  
Ching-Tai Huang ◽  
Shian-Sen Shie ◽  
Po-Yen Huang ◽  
Lin-Hui Su ◽  
...  
Keyword(s):  
Risk Factors ◽  
Acinetobacter Baumannii ◽  
Multidrug Resistant ◽  
Resistant Strains

scholarly journals The optimal pH of AID is skewed from that of its catalytic pocket by DNA-binding residues and surface charge

2021 ◽  
Author(s):  
Atefeh Ghorbani ◽  
Justin John King ◽  
Mani Larijani
Keyword(s):  
Catalytic Activity ◽  
Surface Charge ◽  
Cytidine Deaminase ◽  
Inverse Correlation ◽  
Acidic Ph ◽  
Structural Mechanism ◽  
Positive Surface Charge ◽  
Equivalent Residue ◽  
Binding Residues ◽  
Optimal Ph

Activation-induced cytidine deaminase (AID) is a member of the apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (APOBEC) family of cytidine deaminases. AID mutates immunoglobulin loci to initiate secondary antibody diversification. The APOBEC3 (A3) sub-branch mutates viral pathogens in the cytosol and acidic endosomal compartments. Accordingly, AID functions optimally near neutral pH, while most A3s are acid-adapted (optimal pH 5.5-6.5). To gain a structural understanding for this pH disparity, we constructed high-resolution maps of AID catalytic activity vs pH. We found AID’s optimal pH was 7.3 but it retained most (>70%) of the activity at pH 8. Probing of ssDNA-binding residues near the catalytic pocket, key for bending ssDNA into the pocket (e.g R25) yielded mutants with altered pH preference, corroborating previous findings that the equivalent residue in APOBEC3G (H216) underlies its acidic pH preference. AID from bony fish exhibited more basic optimal pH (pH 7.5-8.1) and several R25-equivalent mutants altered pH preference. Comparison of pH optima across the AID/APOBEC3 family revealed an inverse correlation between positive surface charge and overall catalysis.  The paralogue with the most robust catalytic activity (APOBEC3A) has the lowest surface charge, most acidic pH preference, while the paralogue with the most lethargic catalytic rate (AID) has the most positive surface charge and highest optimal pH. We suggest one possible mechanism is through surface charge dictating an overall optimal pH that is different from the optimal pH of the catalytic pocket microenvironment. These findings illuminate an additional structural mechanism that regulates AID/APOBEC3 mutagenesis.

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