Characterization of eDNA from the Clinical Strain<i>Acinetobacter baumannii</i>AIIMS 7 and Its Role in Biofilm Formation

Sahu, Praveen K.; Iyer, Pavithra S.; Oak, Amrita M.; Pardesi, Karishma; Chopade, Balu A.

doi:10.1100/2012/973436

Cited by 77 publications

(69 citation statements)

References 43 publications

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“…Killing the cells in the outermost layer of biofilms may interrupt the connection between bacterial cells and biofilm-anchoring proteins and then disrupt the biofilm architecture. The eDNA is also involved in biofilm formation and cohesion of biofilms to provide mechanical stability (42)(43)(44). The eDNA in the matrix has been found to increase resistance to cationic antimicrobial peptides and aminoglycosides but not to ␤-lactams (46).…”

Section: Discussionmentioning

confidence: 99%

“…However, there are very few studies that address how the killing of bacteria alters the architecture of the established biofilms. The extracellular matrix of a biofilm is a mixture of extracellular DNA (eDNA), lipids, polysaccharides, and extracellular proteins that provide architectural structure and mechanical stability to the attached bacterial population (42)(43)(44)(45). Many of the proteins in the extracellular matrix have been revealed to polymerize into higher-order structures and anchor to bacterial cells through some proteins (37).…”

Section: Discussionmentioning

confidence: 99%

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Individual or Combined Effects of Meropenem, Imipenem, Sulbactam, Colistin, and Tigecycline on Biofilm-Embedded Acinetobacter baumannii and Biofilm Architecture

Wang

Kuo

Yang

et al. 2016

Antimicrob Agents Chemother

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Acinetobacter baumannii biofilms are difficult to eradicate. We investigated the effects of meropenem (2 mg/liter), imipenem (2 mg/liter), sulbactam (4 mg/liter), colistin (2 mg/liter), and tigecycline (2 mg/liter), alone or in combination, on biofilm-embedded carbapenem-resistant and carbapenem-susceptible A. baumannii (CRAb and CSAb, respectively) cells, as well as on the architecture of the biofilms. A. baumannii ATCC 15151 (Ab15151) and its OXA-82-overproducing transformant, along with two clinical CSAb and two clinical CRAb isolates of differing clonalities, were used. The minimal bactericidal concentrations for biofilm-embedded cells of the six tested isolates were >50-fold those of their planktonic cells. When used individually, meropenem exhibited a higher killing effect than the other four antimicrobials on biofilm-embedded CSAb cells in the colony biofilm assay. For two clinical CRAb isolates, meropenem plus sulbactam or sulbactam plus tigecycline showed >100-fold the bactericidal effect exhibited by these agents used alone after 48 h of treatment. The effect of antimicrobials on the architecture of Ab15151 biofilm emitting green fluorescence was determined by confocal laser scanning microscopy using COMSTAT software. Significant decreases in the maximum biofilm thickness were observed after exposure to meropenem and imipenem. Meropenem plus sulbactam significantly decreased the biomass and mean thickness and increased the roughness coefficient of biofilms, but sulbactam plus tigecycline only decreased the maximum and mean biofilm thickness compared to any of these agents used alone. Meropenem was active against biofilm-embedded CSAb, whereas meropenem plus sulbactam exhibited synergism against biofilm-embedded CRAb and caused significantly more damage to the biofilm architecture than did any of the agents used alone.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Individual or Combined Effects of Meropenem, Imipenem, Sulbactam, Colistin, and Tigecycline on Biofilm-Embedded Acinetobacter baumannii and Biofilm Architecture

Wang

Kuo

Yang

et al. 2016

Antimicrob Agents Chemother

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“…Acinetobacter baumannii AIIMS 7 (GenBank EU779829) isolated and identified in our laboratory has been used. 37 synthesis of agNPs and ultraviolet-visible (UV-Vis) spectra analysis 10 CFU/mL) were suspended into sterile Milli-Q ® water (pH 7) after repeated rinses to remove the traces of media and incubated at 30°C/200 rpm for 72 hours. Cell-free extract (CFE) used for synthesis was collected by passing the supernatant obtained after centrifugation through a 0.2 µm syringe filter (Pall Corporation, Port Washington, NY, USA).…”

Section: Materials and Methods Culturesmentioning

confidence: 99%

Synthesis, optimization, and characterization of silver nanoparticles from Acinetobacter calcoaceticus and their enhanced antibacterial activity when combined with antibiotics

Singh¹,

Wagh²,

Wadhwani³

et al. 2013

IJN

127

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Background The development of nontoxic methods of synthesizing nanoparticles is a major step in nanotechnology to allow their application in nanomedicine. The present study aims to biosynthesize silver nanoparticles (AgNPs) using a cell-free extract of Acinetobacter spp. and evaluate their antibacterial activity. Methods Eighteen strains of Acinetobacter were screened for AgNP synthesis. AgNPs were characterized using various techniques. Reaction parameters were optimized, and their effect on the morphology of AgNPs was studied. The synergistic potential of AgNPs on 14 antibiotics against seven pathogens was determined by disc-diffusion, broth-microdilution, and minimum bactericidal concentration assays. The efficacy of AgNPs was evaluated as per the minimum inhibitory concentration (MIC) breakpoints of the Clinical and Laboratory Standards Institute (CLSI) guidelines. Results Only A. calcoaceticus LRVP54 produced AgNPs within 24 hours. Monodisperse spherical nanoparticles of 8–12 nm were obtained with 0.7 mM silver nitrate at 70°C. During optimization, a blue-shift in ultraviolet-visible spectra was seen. X-ray diffraction data and lattice fringes ( d =0.23 nm) observed under high-resolution transmission electron microscope confirmed the crystallinity of AgNPs. These AgNPs were found to be more effective against Gram-negative compared with Gram-positive microorganisms. Overall, AgNPs showed the highest synergy with vancomycin in the disc-diffusion assay. For Enterobacter aerogenes , a 3.8-fold increase in inhibition zone area was observed after the addition of AgNPs with vancomycin. Reduction in MIC and minimum bactericidal concentration was observed on exposure of AgNPs with antibiotics. Interestingly, multidrug-resistant A. baumannii was highly sensitized in the presence of AgNPs and became susceptible to antibiotics except cephalosporins. Similarly, the vancomycin-resistant strain of Streptococcus mutans was also found to be susceptible to antibiotic treatment when AgNPs were added. These biogenic AgNPs showed significant synergistic activity on the β-lactam class of antibiotics. Conclusion This is the first report of synthesis of AgNPs using A. calcoaceticus LRVP54 and their significant synergistic activity with antibiotics resulting in increased susceptibility of multidrug-resistant bacteria evaluated as per MIC breakpoints of the CLSI standard.

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“…Recently, the horizontal transfer of a carbapenem resistance gene via OMVs was shown in Acinetobacter baumannii (24). The release of DNA-containing OMVs from pathogenic species of Acinetobacter has also been previously reported (25)(26)(27). Acinetobacter baylyi (previously also denoted Acinetobacter calcoaceticus) has been described to release OMVs when grown on hexadecane (28).…”

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confidence: 99%

Gene Transfer Potential of Outer Membrane Vesicles of Acinetobacter baylyi and Effects of Stress on Vesiculation

Fulsundar

Harms

Flaten

et al. 2014

Appl Environ Microbiol

212

197

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dOuter membrane vesicles (OMVs) are continually released from a range of bacterial species. Numerous functions of OMVs, including the facilitation of horizontal gene transfer (HGT) processes, have been proposed. In this study, we investigated whether OMVs contribute to the transfer of plasmids between bacterial cells and species using Gram-negative Acinetobacter baylyi as a model system. OMVs were extracted from bacterial cultures and tested for the ability to vector gene transfer into populations of Escherichia coli and A. baylyi, including naturally transformation-deficient mutants of A. baylyi. Anti-double-stranded DNA (anti-dsDNA) antibodies were used to determine the movement of DNA into OMVs. We also determined how stress affected the level of vesiculation and the amount of DNA in vesicles. OMVs were further characterized by measuring particle size distribution (PSD) and zeta potential. Transmission electron microscopy (TEM) and immunogold labeling were performed using antifluorescein isothiocyanate (anti-FITC)-conjugated antibodies and anti-dsDNA antibodies to track the movement of FITC-labeled and DNA-containing OMVs. Exposure to OMVs isolated from plasmid-containing donor cells resulted in HGT to A. baylyi and E. coli at transfer frequencies ranging from 10 ؊6 to 10 ؊8 , with transfer efficiencies of approximately 10 3 and 10 2 per g of vesicular DNA, respectively. Antibiotic stress was shown to affect the DNA content of OMVs as well as their hydrodynamic diameter and zeta potential. Morphological observations suggest that OMVs from A. baylyi interact with recipient cells in different ways, depending on the recipient species. Interestingly, the PSD measurements suggest that distinct size ranges of OMVs are released from A. baylyi.

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Characterization of eDNA from the Clinical StrainAcinetobacter baumanniiAIIMS 7 and Its Role in Biofilm Formation

Cited by 77 publications

References 43 publications

Individual or Combined Effects of Meropenem, Imipenem, Sulbactam, Colistin, and Tigecycline on Biofilm-Embedded Acinetobacter baumannii and Biofilm Architecture

Individual or Combined Effects of Meropenem, Imipenem, Sulbactam, Colistin, and Tigecycline on Biofilm-Embedded Acinetobacter baumannii and Biofilm Architecture

Synthesis, optimization, and characterization of silver nanoparticles from Acinetobacter calcoaceticus and their enhanced antibacterial activity when combined with antibiotics

Gene Transfer Potential of Outer Membrane Vesicles of Acinetobacter baylyi and Effects of Stress on Vesiculation

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