scholarly journals Gentamicin-Loaded Borate Bioactive Glass Eradicates Osteomyelitis Due to Escherichia coli in a Rabbit Model

2013 ◽  
Vol 57 (7) ◽  
pp. 3293-3298 ◽  
Author(s):  
Zongping Xie ◽  
Xu Cui ◽  
Cunju Zhao ◽  
Wenhai Huang ◽  
Jianqiang Wang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bioactive Glass ◽  
Rabbit Model ◽  
Radiographic Evaluation ◽  
Sustained Drug Release ◽  
Gram Negative ◽  
Content Type ◽  
Rabbit Tibia ◽  
Borate Bioactive Glass

ABSTRACTThe treatment of osteomyelitis induced by Gram-negative bacilli is rarely reported in the literature. This study established a rabbit tibia model of osteomyelitis induced by the Gram-negative bacillusEscherichia coli. Using this model, pellets composed of a chitosan-bonded mixture of borate bioactive glass and gentamicin were evaluatedin vitroandin vivofor the treatment of osteomyelitis induced byEscherichia coli. Our results showed that the pellets in phosphate-buffered saline released gentamicin continuously over 26 days. Without the simultaneous use of a systemic antibiotic, the implantation of the gentamicin-loaded pellets into the osteomyelitis region of the tibia resulted in the eradication of 81.82% of infections, as determined by microbiological, histological and radiographic evaluation, and supported the ingrowth of new bone into the tibia defects after 6 weeks of implantation. The results indicate that the gentamicin-loaded borate bioactive glass implant, combining sustained drug release with the ability to support new bone formation, could provide a method for treating osteomyelitis induced by Gram-negative bacilli.

scholarly journals Comparison of Borate Bioactive Glass and Calcium Sulfate as Implants for the Local Delivery of Teicoplanin in the Treatment of Methicillin-Resistant Staphylococcus aureus-Induced Osteomyelitis in a Rabbit Model

2015 ◽  
Vol 59 (12) ◽  
pp. 7571-7580 ◽  
Author(s):  
Wei-Tao Jia ◽  
Qiang Fu ◽  
Wen-Hai Huang ◽  
Chang-Qing Zhang ◽  
Mohamed N. Rahaman
Keyword(s):  
Staphylococcus Aureus ◽  
Bioactive Glass ◽  
Calcium Sulfate ◽  
Rabbit Model ◽  
Local Delivery ◽  
Methicillin Resistant ◽  
Content Type ◽  
Borate Bioactive Glass ◽  
Phosphate Buffered Saline

ABSTRACTThere is growing interest in biomaterials that can cure bone infection and also regenerate bone. In this study, two groups of implants composed of 10% (wt/wt) teicoplanin (TEC)-loaded borate bioactive glass (designated TBG) or calcium sulfate (TCS) were created and evaluated for their ability to release TECin vitroand to cure methicillin-resistantStaphylococcus aureus(MRSA)-induced osteomyelitis in a rabbit model. When immersed in phosphate-buffered saline (PBS), both groups of implants provided a sustained release of TEC at a therapeutic level for up to 3 to 4 weeks while they were gradually degraded and converted to hydroxyapatite. The TBG implants showed a longer duration of TEC release and better retention of strength as a function of immersion time in PBS. Infected rabbit tibiae were treated by debridement, followed by implantation of TBG or TCS pellets or intravenous injection with TEC, or were left untreated. Evaluation at 6 weeks postimplantation showed that the animals implanted with TBG or TCS pellets had significantly lower radiological and histological scores, lower rates of MRSA-positive cultures, and lower bacterial loads than those preoperatively and those of animals treated intravenously. The level of bone regeneration was also higher in the defects treated with the TBG pellets. The results showed that local TEC delivery was more effective than intravenous administration for the treatment of MRSA-induced osteomyelitis. Borate glass has the advantages of better mechanical strength, more desirable kinetics of release of TEC, and a higher osteogenic capacity and thus could be an effective alternative to calcium sulfate for local delivery of TEC.

scholarly journals Membrane Protein Complex ExbB4-ExbD1-TonB1from Escherichia coli Demonstrates Conformational Plasticity

2015 ◽  
Vol 197 (11) ◽  
pp. 1873-1885 ◽  
Author(s):  
Aleksandr Sverzhinsky ◽  
Jacqueline W. Chung ◽  
Justin C. Deme ◽  
Lucien Fabre ◽  
Kristian T. Levey ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Iron Acquisition ◽  
Proton Translocation ◽  
Three Dimensional ◽  
Structural Data ◽  
Structural Features ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Content Type

ABSTRACTIron acquisition at the outer membrane (OM) of Gram-negative bacteria is powered by the proton motive force (PMF) of the cytoplasmic membrane (CM), harnessed by the CM-embedded complex of ExbB, ExbD, and TonB. Its stoichiometry, ensemble structural features, and mechanism of action are unknown. By panning combinatorial phage libraries, periplasmic regions of dimerization between ExbD and TonB were predicted. Using overexpression of full-length His6-taggedexbB-exbDand S-taggedtonB, we purified detergent-solubilized complexes of ExbB-ExbD-TonB fromEscherichia coli. Protein-detergent complexes of ∼230 kDa with a hydrodynamic radius of ∼6.0 nm were similar to previously purified ExbB4-ExbD2complexes. Significantly, they differed in electronegativity by native agarose gel electrophoresis. The stoichiometry was determined to be ExbB4-ExbD1-TonB1. Single-particle electron microscopy agrees with this stoichiometry. Two-dimensional averaging supported the phage display predictions, showing two forms of ExbD-TonB periplasmic heterodimerization: extensive and distal. Three-dimensional (3D) particle classification showed three representative conformations of ExbB4-ExbD1-TonB1. Based on our structural data, we propose a model in which ExbD shuttles a proton across the CM via an ExbB interprotein rearrangement. Proton translocation would be coupled to ExbD-mediated collapse of extended TonB in complex with ligand-loaded receptors in the OM, followed by repositioning of TonB through extensive dimerization with ExbD. Here we present the first report for purification of the ExbB-ExbD-TonB complex, molar ratios within the complex (4:1:1), and structural biology that provides insights into 3D organization.IMPORTANCEReceptors in the OM of Gram-negative bacteria allow entry of iron-bound siderophores that are necessary for pathogenicity. Numerous iron-acquisition strategies rely upon a ubiquitous and unique protein for energization: TonB. Complexed with ExbB and ExbD, the Ton system links the PMF to OM transport. Blocking iron uptake by targeting a vital nanomachine holds promise in therapeutics. Despite much research, the stoichiometry, structural arrangement, and molecular mechanism of the CM-embedded ExbB-ExbD-TonB complex remain unreported. Here we demonstratein vitroevidence of ExbB4-ExbD1-TonB1complexes. Using 3D EM, we reconstructed the complex in three conformational states that show variable ExbD-TonB heterodimerization. Our structural observations form the basis of a model for TonB-mediated iron acquisition.

scholarly journals Activities of Fosfomycin, Tigecycline, Colistin, and Gentamicin against Extended-Spectrum-β-Lactamase-Producing Escherichia coli in a Foreign-Body Infection Model

2013 ◽  
Vol 57 (3) ◽  
pp. 1421-1427 ◽  
Author(s):  
Stéphane Corvec ◽  
Ulrika Furustrand Tafin ◽  
Bertrand Betrisey ◽  
Olivier Borens ◽  
Andrej Trampuz
Keyword(s):  
Escherichia Coli ◽  
Foreign Body ◽  
Single Agent ◽  
Infection Model ◽  
Minimal Bactericidal Concentration ◽  
Synergistic Activity ◽  
Cure Rate ◽  
Gram Negative ◽  
Content Type

ABSTRACTLimited antimicrobial agents are available for the treatment of implant-associated infections caused by fluoroquinolone-resistant Gram-negative bacilli. We compared the activities of fosfomycin, tigecycline, colistin, and gentamicin (alone and in combination) against a CTX-M15-producing strain ofEscherichia coli(Bj HDE-1)in vitroand in a foreign-body infection model. The MIC and the minimal bactericidal concentration in logarithmic phase (MBClog) and stationary phase (MBCstat) were 0.12, 0.12, and 8 μg/ml for fosfomycin, 0.25, 32, and 32 μg/ml for tigecycline, 0.25, 0.5, and 2 μg/ml for colistin, and 2, 8, and 16 μg/ml for gentamicin, respectively. In time-kill studies, colistin showed concentration-dependent activity, but regrowth occurred after 24 h. Fosfomycin demonstrated rapid bactericidal activity at the MIC, and no regrowth occurred. Synergistic activity between fosfomycin and colistinin vitrowas observed, with no detectable bacterial counts after 6 h. In animal studies, fosfomycin reduced planktonic counts by 4 log10CFU/ml, whereas in combination with colistin, tigecycline, or gentamicin, it reduced counts by >6 log10CFU/ml. Fosfomycin was the only single agent which was able to eradicateE. colibiofilms (cure rate, 17% of implanted, infected cages). In combination, colistin plus tigecycline (50%) and fosfomycin plus gentamicin (42%) cured significantly more infected cages than colistin plus gentamicin (33%) or fosfomycin plus tigecycline (25%) (P< 0.05). The combination of fosfomycin plus colistin showed the highest cure rate (67%), which was significantly better than that of fosfomycin alone (P< 0.05). In conclusion, the combination of fosfomycin plus colistin is a promising treatment option for implant-associated infections caused by fluoroquinolone-resistant Gram-negative bacilli.

scholarly journals In VitroActivities of 21 Antimicrobial Agents Alone and in Combination with Aminoglycosides or Fluoroquinolones against Extended-Spectrum-β-Lactamase-Producing Escherichia coli Isolates Causing Bacteremia

2015 ◽  
Vol 59 (9) ◽  
pp. 5834-5837 ◽  
Author(s):  
Min Kyeong Cha ◽  
Cheol-In Kang ◽  
So Hyun Kim ◽  
Sun Young Cho ◽  
Young Eun Ha ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Therapy ◽  
Antimicrobial Agents ◽  
Empirical Therapy ◽  
Gram Negative ◽  
Content Type ◽  
South Korean ◽  
Extended Spectrum ◽  
High Prevalence

ABSTRACTWe evaluated thein vitroactivity of various antimicrobials alone and in combination against 291 extended-spectrum-β-lactamase-producingEscherichia coli(ESBL-EC) isolates causing bacteremia in South Korean hospitals. Ceftazidime, cefepime, and piperacillin-tazobactam in combination with amikacin showed greater activity than found in combination with ciprofloxacin. In settings with a high prevalence of ESBL-producing pathogens, combination aminoglycoside antimicrobial therapy, especially with amikacin, may be considered for empirical therapy against suspected Gram-negative sepsis as a carbapenem-saving strategy.

scholarly journals A Double, Long Polar Fimbria Mutant of Escherichia coli O157:H7 Expresses Curli and Exhibits ReducedIn VivoColonization

2012 ◽  
Vol 80 (3) ◽  
pp. 914-920 ◽  
Author(s):  
Sonja J. Lloyd ◽  
Jennifer M. Ritchie ◽  
Maricarmen Rojas-Lopez ◽  
Carla A. Blumentritt ◽  
Vsevolod L. Popov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Epithelial Cells ◽  
Rabbit Model ◽  
Intestinal Colonization ◽  
Content Type ◽  
Regulatory Pathways ◽  
E Coli ◽  
Reverse Transcription Pcr

Escherichia coliO157:H7 causes food and waterborne enteric infections that can result in hemorrhagic colitis and life-threatening hemolytic uremic syndrome. Intimate adherence of the bacteria to intestinal epithelial cells is mediated by intimin, butE. coliO157:H7 also possess several other putative adhesins, including curli and two operons that encode long polar fimbriae (Lpf). To assess the importance of Lpf for intestinal colonization, we performed competition experiments betweenE. coliO157:H7 and an isogenic ΔlpfA1ΔlpfA2double mutant in the infant rabbit model. The mutant was outcompeted in the ileum, cecum, and midcolon, suggesting that Lpf contributes to intestinal colonization. In contrast, the ΔlpfA1ΔlpfA2mutant showed increased adherence to colonic epithelial cellsin vitro. Transmission electron microscopy revealed curli-like structures on the surface of the ΔlpfA1ΔlpfA2mutant, and the presence of curli was confirmed by Congo red binding, immunogold-labeling electron microscopy, immunoblotting, and quantitative real-time reverse transcription-PCR (qRT-PCR) measuringcsgAexpression. However, deletion ofcsgA, which encodes the major curli subunit, does not appear to affect intestinal colonization. In addition to suggesting that Lpf can contribute to EHEC intestinal colonization, our observations indicate that the regulatory pathways governing the expression of Lpf and curli are interdependent.

Interleukin-8 is a major component of pleural liquid chemotactic activity in a rabbit model of endotoxin pleurisy

1994 ◽  
Vol 267 (2) ◽  
pp. L137-L144 ◽  
Author(s):  
A. M. Boylan ◽  
C. A. Hebert ◽  
M. Sadick ◽  
W. L. Wong ◽  
A. Chuntharapai ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Monoclonal Antibodies ◽  
Neutrophil Migration ◽  
Rabbit Model ◽  
Pleural Space ◽  
Chemotactic Activity ◽  
Interleukin 8 ◽  
Gram Negative

Gram-negative endotoxin induces production of the potent chemotactic factor interleukin-8 (IL-8) in vitro; however, the importance of IL-8 in endotoxin-induced inflammation in vivo is unknown. We asked whether IL-8 is an important contributor to chemotactic activity in acute inflammatory liquids formed in response to endotoxin, and, if present, what concentrations of IL-8 antigen are generated. For these studies, we cloned and expressed rabbit recombinant IL-8 (rrIL-8), developed specific anti-rabbit IL-8 monoclonal antibodies (mAb), and then used these reagents to develop assays to detect rabbit IL-8 bioactivity and measure rabbit IL-8 antigen. Escherichia coli endotoxin (20 ng/ml, n = 4, or 2,000 ng/ml, n = 4) was instilled into the pleural space of eight rabbits for 6 h. Rabbit IL-8 bioactivity in the endotoxin pleurisy samples was assayed by measuring the migration of rabbit neutrophils toward the pleural liquid under two different conditions: 1) after addition of an anti-IL-8 neutralizing mAb and 2) after desensitization of the neutrophils to rrIL-8. Addition of the anti-IL-8 mAb decreased neutrophil migration toward the pleural liquid by 65 +/- 13 and 75 +/- 22% (mean +/- SE, after 20 and 2,000 ng/ml endotoxin, respectively; P < 0.01 compared with a control mAb). Desensitization of neutrophils to rrIL-8 decreased their migration toward the pleural liquid by 72 +/- 5% (P = 0.03, compared with exposure of neutrophils to buffer alone.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Paenipeptin Analogues Potentiate Clarithromycin and Rifampin against mcr-1-Mediated Polymyxin-Resistant Escherichia coli In Vivo

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Sun Hee Moon ◽  
Yihong Kaufmann ◽  
En Huang
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Resistance ◽  
Outer Membrane ◽  
Infection Model ◽  
Gram Negative ◽  
Content Type ◽  
E Coli ◽  
Log Reduction

ABSTRACT Polymyxin resistance mediated by the mcr-1 gene threatens the last-resort antibiotics. Linear lipopeptide paenipeptin analogues 1 and 15 disrupted the outer membrane of Gram-negative pathogens and potentiated clarithromycin and rifampin against mcr-1-positive Escherichia coli from the FDA-CDC Antimicrobial Resistance Isolate Bank. In the presence of paenipeptin, clarithromycin and rifampin resulted in over 3-log reduction of E. coli in vitro. Moreover, paenipeptin-antibiotic combinations significantly reduced E. coli in a murine thigh infection model.

scholarly journals In VivoComparison of CXA-101 (FR264205) with and without Tazobactam versus Piperacillin-Tazobactam Using Human Simulated Exposures against Phenotypically Diverse Gram-Negative Organisms

2011 ◽  
Vol 56 (1) ◽  
pp. 544-549 ◽  
Author(s):  
Catharine C. Bulik ◽  
Pamela R. Tessier ◽  
Rebecca A. Keel ◽  
Christina A. Sutherland ◽  
David P. Nicolau
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Resistance Mechanisms ◽  
Infection Model ◽  
Gram Negative ◽  
Content Type ◽  
Comparison Groups ◽  
Gram Negative Organisms

ABSTRACTCXA-101 is a novel antipseudomonal cephalosporin with enhanced activity against Gram-negative organisms displaying various resistance mechanisms. This study evaluates the efficacy of exposures approximating human percent free time above the MIC (%fT > MIC) of CXA-101 with or without tazobactam and piperacillin-tazobactam (TZP) against target Gram-negative organisms, including those expressing extended-spectrum β-lactamases (ESBLs). Sixteen clinical Gram-negative isolates (6Pseudomonas aeruginosaisolates [piperacillin-tazobactam MIC range, 8 to 64 μg/ml], 4Escherichia coliisolates (2 ESBL and 2 non-ESBL expressing), and 4Klebsiella pneumoniaeisolates (3 ESBL and 1 non-ESBL expressing) were used in an immunocompetent murine thigh infection model. After infection, groups of mice were administered doses of CXA-101 with or without tazobactam (2:1) designed to approximate the %fT > MIC observed in humans given 1 g of CXA-101 with or without tazobactam every 8 h as a 1-h infusion. As a comparison, groups of mice were administered piperacillin-tazobactam doses designed to approximate the %fT > MIC observed in humans given 4.5 g piperacillin-tazobactam every 6 h as a 30-min infusion. Predicted piperacillin-tazobactam %fT > MIC exposures of greater than 40% resulted in static to >1 log decreases in CFU in non-ESBL-expressing organisms with MICs of ≤32 μg/ml after 24 h of therapy. Predicted CXA-101 with or without tazobactam %fT > MIC exposures of ≥37.5% resulted in 1- to 3-log-unit decreases in CFU in non-ESBL-expressing organisms, with MICs of ≤16 μg/ml after 24 h of therapy. With regard to the ESBL-expressing organisms, the inhibitor combinations showed enhanced CFU decreases versus CXA-101 alone. Due to enhancedin vitropotency and resultant increasedin vivoexposure, CXA-101 produced statistically significant reductions in CFU in 9 isolates compared with piperacillin-tazobactam. The addition of tazobactam to CXA-101 produced significant reductions in CFU for 7 isolates compared with piperacillin-tazobactam. Overall, human simulated exposures of CXA-101 with or without tazobactam demonstrated improved efficacy versus piperacillin-tazobactam.

scholarly journals Prevention of Biofilm Colonization by Gram-Negative Bacteria on Minocycline-Rifampin-Impregnated Catheters Sequentially Coated with Chlorhexidine

2013 ◽  
Vol 58 (2) ◽  
pp. 1179-1182 ◽  
Author(s):  
Mohamed A. Jamal ◽  
Joel S. Rosenblatt ◽  
Ray Y. Hachem ◽  
Jiang Ying ◽  
Egbert Pravinkumar ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Stenotrophomonas Maltophilia ◽  
Enterobacter Cloacae ◽  
Central Line ◽  
Multidrug Resistant ◽  
Gram Negative Bacteria ◽  
The Novel ◽  
Gram Negative ◽  
Content Type

ABSTRACTResistant Gram-negative bacteria are increasing central-line-associated bloodstream infection threats. To better combat this, chlorhexidine (CHX) was added to minocycline-rifampin (M/R) catheters. Thein vitroantimicrobial activity of CHX-M/R catheters against multidrug resistant, Gram-negativeAcinetobacter baumannii,Enterobacter cloacae,Escherichia coli,Klebsiella pneumoniae,Pseudomonas aeruginosa, andStenotrophomonas maltophiliawas tested. M/R and CHX-silver sulfadiazine (CHX/SS) catheters were used as comparators. The novel CHX-M/R catheters were significantly more effective (P< 0.0001) than CHX/SS or M/R catheters in preventing biofilm colonization and showed better antimicrobial durability.

scholarly journals ZN148 Is a Modular Synthetic Metallo-β-Lactamase Inhibitor That Reverses Carbapenem Resistance in Gram-Negative Pathogens In Vivo

2020 ◽  
Vol 64 (6) ◽  
Author(s):  
Ørjan Samuelsen ◽  
Ove Alexander Høgmoen Åstrand ◽  
Christopher Fröhlich ◽  
Adam Heikal ◽  
Susann Skagseth ◽  
...  
Keyword(s):  
Active Site ◽  
Therapeutic Potential ◽  
Treatment Options ◽  
Carbapenem Resistance ◽  
Functional Space ◽  
Bactericidal Effect ◽  
Gram Negative ◽  
Content Type

ABSTRACT Carbapenem-resistant Gram-negative pathogens are a critical public health threat and there is an urgent need for new treatments. Carbapenemases (β-lactamases able to inactivate carbapenems) have been identified in both serine β-lactamase (SBL) and metallo-β-lactamase (MBL) families. The recent introduction of SBL carbapenemase inhibitors has provided alternative therapeutic options. Unfortunately, there are no approved inhibitors of MBL-mediated carbapenem-resistance and treatment options for infections caused by MBL-producing Gram-negatives are limited. Here, we present ZN148, a zinc-chelating MBL-inhibitor capable of restoring the bactericidal effect of meropenem and in vitro clinical susceptibility to carbapenems in >98% of a large international collection of MBL-producing clinical Enterobacterales strains (n = 234). Moreover, ZN148 was able to potentiate the effect of meropenem against NDM-1-producing Klebsiella pneumoniae in a murine neutropenic peritonitis model. ZN148 showed no inhibition of the human zinc-containing enzyme glyoxylase II at 500 μM, and no acute toxicity was observed in an in vivo mouse model with cumulative dosages up to 128 mg/kg. Biochemical analysis showed a time-dependent inhibition of MBLs by ZN148 and removal of zinc ions from the active site. Addition of exogenous zinc after ZN148 exposure only restored MBL activity by ∼30%, suggesting an irreversible mechanism of inhibition. Mass-spectrometry and molecular modeling indicated potential oxidation of the active site Cys221 residue. Overall, these results demonstrate the therapeutic potential of a ZN148-carbapenem combination against MBL-producing Gram-negative pathogens and that ZN148 is a highly promising MBL inhibitor that is capable of operating in a functional space not presently filled by any clinically approved compound.

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