scholarly journals Effect of Pressure-Induced Changes in the Ionization Equilibria of Buffers on Inactivation of Escherichia coli and Staphylococcus aureus by High Hydrostatic Pressure

2013 ◽  
Vol 79 (13) ◽  
pp. 4041-4047 ◽  
Author(s):  
Elisa Gayán ◽  
Santiago Condón ◽  
Ignacio Álvarez ◽  
Maria Nabakabaya ◽  
Bernard Mackey
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Survival Rates ◽  
Practical Significance ◽  
Protective Mechanisms ◽  
Content Type ◽  
Monovalent Ions ◽  
Ion Effects ◽  
Ionization Equilibria ◽  
Reaction Volumes

ABSTRACTSurvival rates ofEscherichia coliandStaphylococcus aureusafter high-pressure treatment in buffers that had large or small reaction volumes (ΔV°), and which therefore underwent large or small changes in pH under pressure, were compared. At a low buffer concentration of 0.005 M, survival was, as expected, better in MOPS (morpholinepropanesulfonic acid), HEPES, and Tris, whose ΔV° values are approximately 5.0 to 7.0 cm3mol−1, than in phosphate or dimethyl glutarate (DMG), whose ΔV° values are about −25 cm3mol−1. However, at a concentration of 0.1 M, survival was unexpectedly better in phosphate and DMG than in MOPS, HEPES, or Tris. This was because the baroprotective effect of phosphate and DMG increased much more rapidly with increasing concentration than it did with MOPS, HEPES, or Tris. Further comparisons of survival in solutions of salts expected to cause large electrostriction effects (Na2SO4and CaCl2) and those causing lower electrostriction (NaCl and KCl) were made. The salts with divalent ions were protective at much lower concentrations than salts with monovalent ions. Buffers and salts both protected against transient membrane disruption inE. coli, but the molar concentrations necessary for membrane protection were much lower for phosphate and Na2SO4than for HEPES and NaCl. Possible protective mechanisms discussed include effects of electrolytes on water compressibility and kosmotropic and specific ion effects. The results of this systematic study will be of considerable practical significance in studies of pressure inactivation of microbes under defined conditions but also raise important fundamental questions regarding the mechanisms of baroprotection by ionic solutes.

scholarly journals Effects of Tedizolid Phosphate on Survival Outcomes and Suppression of Production of Staphylococcal Toxins in a Rabbit Model of Methicillin-Resistant Staphylococcus aureus Necrotizing Pneumonia

2017 ◽  
Vol 61 (4) ◽  
Author(s):  
Vien T. M. Le ◽  
Hoan N. Le ◽  
Marcos Gabriel Pinheiro ◽  
Kenneth J. Hahn ◽  
Mary L. Dinh ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Bacterial Production ◽  
Protective Efficacy ◽  
Survival Rates ◽  
Rabbit Model ◽  
Rank Test ◽  
Necrotizing Pneumonia ◽  
Time Curve ◽  
Content Type

ABSTRACT The protective efficacy of tedizolid phosphate, a novel oxazolidinone that potently inhibits bacterial protein synthesis, was compared to those of linezolid, vancomycin, and saline in a rabbit model of Staphylococcus aureus necrotizing pneumonia. Tedizolid phosphate was administered to rabbits at 6 mg/kg of body weight intravenously twice daily, which yielded values of the 24-h area under the concentration-time curve approximating those found in humans. The overall survival rate was 83% for rabbits treated with 6 mg/kg tedizolid phosphate twice daily and 83% for those treated with 50 mg/kg linezolid thrice daily (P = 0.66 by the log-rank test versus the results obtained with tedizolid phosphate). These survival rates were significantly greater than the survival rates of 17% for rabbits treated with 30 mg/kg vancomycin twice daily (P = 0.003) and 17% for rabbits treated with saline (P = 0.002). The bacterial count in the lungs of rabbits treated with tedizolid phosphate was significantly decreased compared to that in the lungs of rabbits treated with saline, although it was not significantly different from that in the lungs of rabbits treated with vancomycin or linezolid. The in vivo bacterial production of alpha-toxin and Panton-Valentine leukocidin, two key S. aureus-secreted toxins that play critical roles in the pathogenesis of necrotizing pneumonia, in the lungs of rabbits treated with tedizolid phosphate and linezolid was significantly inhibited compared to that in the lungs of rabbits treated with vancomycin or saline. Taken together, these results indicate that tedizolid phosphate is superior to vancomycin for the treatment of S. aureus necrotizing pneumonia because it inhibits the bacterial production of lung-damaging toxins at the site of infection.

scholarly journals Screening of Escherichia coli Species Biodiversity Reveals New Biofilm-Associated Antiadhesion Polysaccharides

mBio ◽  
2011 ◽  
Vol 2 (3) ◽  
Author(s):  
Olaya Rendueles ◽  
Laetitia Travier ◽  
Patricia Latour-Lambert ◽  
Thierry Fontaine ◽  
Julie Magnus ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Bacterial Adhesion ◽  
Bioactive Molecules ◽  
Bacterial Biofilms ◽  
Gram Positive ◽  
Content Type ◽  
E Coli ◽  
Species Biodiversity

ABSTRACTBacterial biofilms often form multispecies communities in which complex but ill-understood competition and cooperation interactions occur. In light of the profound physiological modifications associated with this lifestyle, we hypothesized that the biofilm environment might represent an untapped source of natural bioactive molecules interfering with bacterial adhesion or biofilm formation. We produced cell-free solutions extracted fromin vitromature biofilms formed by 122 naturalEscherichia coliisolates, and we screened these biofilm extracts for antiadhesion molecules active on a panel of Gram-positive and Gram-negative bacteria. Using this approach, we showed that 20% of the tested biofilm extracts contained molecules that antagonize bacterial growth or adhesion. We characterized a compound, produced by a commensal animalE. colistrain, for which activity is detected only in biofilm extract. Biochemical and genetic analyses showed that this compound corresponds to a new type of released high-molecular-weight polysaccharide whose biofilm-associated production is regulated by the RfaH protein. We demonstrated that the antiadhesion activity of this polysaccharide was restricted to Gram-positive bacteria and that its production reduced susceptibility to invasion and provided rapid exclusion ofStaphylococcus aureusfrom mixedE. coliandS. aureusbiofilms. Our results therefore demonstrate that biofilms contain molecules that contribute to the dynamics of mixed bacterial communities and that are not or only poorly detected in unconcentrated planktonic supernatants. Systematic identification of these compounds could lead to strategies that limit pathogen surface colonization and reduce the burden associated with the development of bacterial biofilms on medical devices.IMPORTANCEWe sought to demonstrate that bacterial biofilms are reservoirs for unknown molecules that antagonize bacterial adhesion. The use of natural strains representative ofEscherichia colispecies biodiversity showed that nonbiocidal antiadhesion polysaccharides are frequently found in mature biofilm extracts (bacterium-free suspensions which contain soluble molecules produced within the biofilm). Release of an antiadhesion polysaccharide confers a competitive advantage upon the producing strain against clinically relevant pathogens such asStaphylococcus aureus. Hence, exploring the biofilm environment provides a better understanding of bacterial interactions within complex communities and could lead to improved control of pathogen colonization.

Are restaurant menus vectors of bacterial cross-contamination? A pilot study in Turkey

2017 ◽  
Vol 119 (2) ◽  
pp. 401-410 ◽  
Author(s):  
Saniye Bilici ◽  
Hande Mortas ◽  
Süleyman Köse ◽  
Semra Navruz Varli ◽  
Büsra Ayhan
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Pilot Study ◽  
Design Methodology ◽  
Adenosine Monophosphate ◽  
Cross Contamination ◽  
Content Type ◽  
Study Results ◽  
High Level ◽  
Cleaning Protocol

Purpose The purpose of this paper is to evaluate the hygiene of laminated menus. Design/methodology/approach The cleanliness of 41 laminated menus from first-class restaurant in Ankara, Turkey, was monitored according to the level of bioluminescence measured using a rapid hygiene monitor (Lumitester PD-20 and LuciPac Pen). Aerobic colonies, Escherichia coli, Enterobacteriaceae spp., and Staphylococcus aureus were enumerated. Findings Based on the adenosine triphosphate+adenosine monophosphate hygiene monitoring levels, analyses showed impurity in 82.9 percent of the samples. The aerobic colony count on the restaurant menus showed a mean 1.52 log cfu/cm2. The study results demonstrated a high-level impurity on the menus in first-class restaurants in Ankara. Originality/value This study is the first in Turkey to assess the microbiological load of menus. This paper adds relevant insights into the assessment of menu hygiene and highlights the high contamination of the restaurant menus. Useful information about including the restaurant menus in the daily cleaning protocol is provided.

scholarly journals X-Ray Absorption Near-Edge Structure (XANES) Spectroscopy Study of the Interaction of Silver Ions with Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli

2013 ◽  
Vol 79 (20) ◽  
pp. 6385-6390 ◽  
Author(s):  
Gudrun Lisa Bovenkamp ◽  
Ulrike Zanzen ◽  
Katla Sai Krishna ◽  
Josef Hormes ◽  
Alexander Prange
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Silver Ions ◽  
Xanes Spectroscopy ◽  
Gram Positive ◽  
Edge Structure ◽  
Content Type ◽  
X Ray ◽  
X Ray Absorption

ABSTRACTSilver ions are widely used as antibacterial agents, but the basic molecular mechanism of this effect is still poorly understood. X-ray absorption near-edge structure (XANES) spectroscopy at the AgLIII, SK, and PKedges reveals the chemical forms of silver inStaphylococcus aureusandEscherichia coli(Ag+treated). The AgLIII-edge XANES spectra of the bacteria are all slightly different and very different from the spectra of silver ions (silver nitrate and silver acetate), which confirms that a reaction occurs. Death or inactivation of bacteria was observed by plate counting and light microscopy. Silver bonding to sulfhydryl groups (Ag-S) in cysteine and Ag-N or Ag-O bonding in histidine, alanine, anddl-aspartic acid was detected by using synthesized silver-amino acids. Significantly lower silver-cysteine content, coupled with higher silver-histidine content, in Gram-positiveS. aureusandListeria monocytogenescells indicates that the peptidoglycan multilayer could be buffering the biocidal effect of silver on Gram-positive bacteria, at least in part. Bonding of silver to phosphate groups was not detected. Interaction with DNA or proteins can occur through Ag-N bonding. The formation of silver-cysteine can be confirmed for both bacterial cell types, which supports the hypothesis that enzyme-catalyzed reactions and the electron transport chain within the cell are disrupted.

scholarly journals Staphylococcus aureus Formyl-Methionyl Transferase Mutants Demonstrate Reduced Virulence Factor Production and Pathogenicity

2013 ◽  
Vol 57 (7) ◽  
pp. 2929-2936 ◽  
Author(s):  
Thomas Lewandowski ◽  
Jianzhong Huang ◽  
Frank Fan ◽  
Shannon Rogers ◽  
Daniel Gentry ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factor ◽  
Survival Rates ◽  
Extracellular Proteins ◽  
High Survival ◽  
Invasive Infection ◽  
Loss Of Function ◽  
Content Type ◽  
Factor Production ◽  
Virulence Factor Production

ABSTRACTInhibitors of peptide deformylase (PDF) represent a new class of antibacterial agents with a novel mechanism of action. Mutations that inactivate formyl methionyl transferase (FMT), the enzyme that formylates initiator methionyl-tRNA, lead to an alternative initiation of protein synthesis that does not require deformylation and are the predominant cause of resistance to PDF inhibitors inStaphylococcus aureus. Here, we report that loss-of-function mutations in FMT impart pleiotropic effects that include a reduced growth rate, a nonhemolytic phenotype, and a drastic reduction in production of multiple extracellular proteins, including key virulence factors, such as α-hemolysin and Panton-Valentine leukocidin (PVL), that have been associated withS. aureuspathogenicity. Consequently,S. aureusFMT mutants are greatly attenuated in neutropenic and nonneutropenic murine pyelonephritis infection models and show very high survival rates compared with wild-typeS. aureus. These newly discovered effects on extracellular virulence factor production demonstrate that FMT-null mutants have a more severe fitness cost than previously anticipated, leading to a substantial loss of pathogenicity and a restricted ability to produce an invasive infection.

scholarly journals Regional Resistance Surveillance Program Results for 12 Asia-Pacific Nations (2011)

2013 ◽  
Vol 57 (11) ◽  
pp. 5721-5726 ◽  
Author(s):  
Rodrigo E. Mendes ◽  
Myrna Mendoza ◽  
Kirnpal K. Banga Singh ◽  
Mariana Castanheira ◽  
Jan M. Bell ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Streptococcus Pneumoniae ◽  
South Korea ◽  
Geographic Region ◽  
Asia Pacific ◽  
Surveillance Program ◽  
Broth Microdilution ◽  
Content Type

ABSTRACTThe Regional Resistance Surveillance program monitored susceptibility rates and developing resistance by geographic region, including 12 Asia-Pacific (APAC) countries. Reference broth microdilution methods for susceptibility/interpretations were applied, processing 5,053 strains. AmongStaphylococcus aureusisolates (37% methicillin-resistantS. aureus[MRSA], highest in South Korea [73%]), linezolid (LZD), tigecycline (TIG), and vancomycin were 100% active, but 33 and 34% of strains were levofloxacin (LEV) or macrolide resistant, respectively.Streptococcus pneumoniaewas most resistant to β-lactams and macrolides (45%) but was LZD, LEV, and TIG susceptible (>98%). Extended-spectrum β-lactamase (ESBL) phenotype rates inEscherichia coliandKlebsiellaspp. were 48 and 47%, respectively, and were highest in Taiwan, at 75 to 91%. The best anti-ESBL-phenotype agents were amikacin (81 to 96% susceptible), colistin (COL; >98%), TIG (>98%), and carbapenems (81 to 97%).Pseudomonas aeruginosashowed ≥20% resistance to all drugs except COL (99% susceptible). In conclusion, endemic evolving antimicrobial resistances in APAC nations show compromised roles for many commonly used antimicrobials.

scholarly journals MEDI4893* Promotes Survival and Extends the Antibiotic Treatment Window in a Staphylococcus aureus Immunocompromised Pneumonia Model

2015 ◽  
Vol 59 (8) ◽  
pp. 4526-4532 ◽  
Author(s):  
L. Hua ◽  
T. S. Cohen ◽  
Y. Shi ◽  
V. Datta ◽  
J. J. Hilliard ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Treatment ◽  
Adjunctive Therapy ◽  
Survival Rates ◽  
Passive Immunization ◽  
Bacterial Overgrowth ◽  
Content Type ◽  
Increased Risk ◽  
Immunocompromised Mice ◽  
Treatment Window

ABSTRACTImmunocompromised individuals are at increased risk ofStaphylococcus aureuspneumonia. Neutralization of alpha-toxin (AT) with the monoclonal antibody (MAb) MEDI4893* protects normal mice fromS. aureuspneumonia; however, the effects of the MAb in immunocompromised mice have not been reported. In this study, passive immunization with MEDI4893* increased survival rates and reduced bacterial numbers in the lungs in an immunocompromised murineS. aureuspneumonia model. Lungs from infected mice exhibited alveolar epithelial damage, protein leakage, and bacterial overgrowth, whereas lungs from mice passively immunized with MEDI4893* retained a healthy architecture, with an intact epithelial barrier. Adjunctive therapy or prophylaxis with a subtherapeutic MEDI4893* dose combined with subtherapeutic doses of vancomycin or linezolid improved survival rates, compared with the monotherapies. Furthermore, coadministration of MEDI4893* with vancomycin or linezolid extended the antibiotic treatment window. These data suggest that MAb-mediated neutralization of AT holds promise in strategies for prevention and adjunctive therapy among immunocompromised patients.

scholarly journals Comparison of Transcriptional Responses and Metabolic Alterations in Three Multidrug-Resistant Model Microorganisms, Staphylococcus aureus ATCC BAA-39, Escherichia coli ATCC BAA-196, and Acinetobacter baumannii ATCC BAA-1790, on Exposure to Iodine-Containing Nano-micelle Drug FS-1

mSystems ◽  
2021 ◽  
Vol 6 (2) ◽  
Author(s):  
Ilya S. Korotetskiy ◽  
Sergey V. Shilov ◽  
Tatyana V. Kuznetsova ◽  
Aleksandr I. Ilin ◽  
Monique Joubert ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Gene Regulation ◽  
Growth Phase ◽  
Multidrug Resistant ◽  
Genome Sequences ◽  
Antibiotic Resistant ◽  
Content Type ◽  
Reference Strains ◽  
Sublethal Concentrations

ABSTRACT Iodine is one of the oldest antimicrobial agents. Until now, there have been no reports on acquiring resistance to iodine. Recent studies showed promising results on application of iodine-containing nano-micelles, FS-1, against antibiotic-resistant pathogens as a supplement to antibiotic therapy. The mechanisms of the action, however, remain unclear. The aim of this study was to perform a holistic analysis and comparison of gene regulation in three phylogenetically distant multidrug-resistant reference strains representing pathogens associated with nosocomial infections from the ATCC culture collection: Escherichia coli BAA-196, Staphylococcus aureus BAA-39, and Acinetobacter baumannii BAA-1790. These cultures were treated by a 5-min exposure to sublethal concentrations of the iodine-containing drug FS-1 applied in the late lagging phase and the middle of the logarithmic growth phase. Complete genome sequences of these strains were obtained in the previous studies. Gene regulation was studied by total RNA extraction and Ion Torrent sequencing followed by mapping the RNA reads against the reference genome sequences and statistical processing of read counts using the DESeq2 algorithm. It was found that the treatment of bacteria with FS-1 profoundly affected the expression of many genes involved in the central metabolic pathways; however, alterations of the gene expression profiles were species specific and depended on the growth phase. Disruption of respiratory electron transfer membrane complexes, increased penetrability of bacterial cell walls, and osmotic and oxidative stresses leading to DNA damage were the major factors influencing the treated bacteria. IMPORTANCE Infections caused by antibiotic-resistant bacteria threaten public health worldwide. Combinatorial therapy in which antibiotics are administered together with supplementary drugs improving susceptibility of pathogens to the regular antibiotics is considered a promising way to overcome this problem. An induction of antibiotic resistance reversion by the iodine-containing nano-micelle drug FS-1 has been reported recently. This drug is currently under clinical trials in Kazakhstan against multidrug-resistant tuberculosis. The effects of released iodine on metabolic and regulatory processes in bacterial cells remain unexplored. The current work provides an insight into gene regulation in the antibiotic-resistant nosocomial reference strains treated with iodine-containing nanoparticles. This study sheds light on unexplored bioactivities of iodine and the mechanisms of its antibacterial effect when applied in sublethal concentrations. This knowledge will aid in the future design of new drugs against antibiotic-resistant infections.

scholarly journals The tva(A) Gene from Brachyspira hyodysenteriae Confers Decreased Susceptibility to Pleuromutilins and Streptogramin A in Escherichia coli

2019 ◽  
Vol 63 (9) ◽  
Author(s):  
Ana B. García-Martín ◽  
Sybille Schwendener ◽  
Vincent Perreten
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Minor Effect ◽  
Content Type ◽  
Brachyspira Hyodysenteriae ◽  
Resistance Phenotype ◽  
E Coli ◽  
Direct Association ◽  
A Minor

ABSTRACT The tva(A) gene suspected to confer resistance to pleuromutilins in Brachyspira hyodysenteriae was tested for functionality in Escherichia coli AG100A and Staphylococcus aureus RN4220. Expression of the cloned tva(A) gene conferred decreased susceptibility to pleuromutilin (P) and streptogramin A (SA) antibiotics in E. coli and had a minor effect in S. aureus. The finding provides evidence of the direct association of tva(A) with the PSA resistance phenotype.

scholarly journals Mechanisms of Inactivation by High-Voltage Atmospheric Cold Plasma Differ for Escherichia coli and Staphylococcus aureus

2015 ◽  
Vol 82 (2) ◽  
pp. 450-458 ◽  
Author(s):  
L. Han ◽  
S. Patil ◽  
D. Boehm ◽  
V. Milosavljević ◽  
P. J. Cullen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
High Voltage ◽  
Dna Cleavage ◽  
Cold Plasma ◽  
Treatment Time ◽  
Enzyme Inactivation ◽  
Content Type ◽  
Intracellular Ros ◽  
Wide Range

ABSTRACTAtmospheric cold plasma (ACP) is a promising nonthermal technology effective against a wide range of pathogenic microorganisms. Reactive oxygen species (ROS) play a crucial inactivation role when air or other oxygen-containing gases are used. With strong oxidative stress, cells can be damaged by lipid peroxidation, enzyme inactivation, and DNA cleavage. Identification of ROS and an understanding of their role are important for advancing ACP applications for a range of complex microbiological issues. In this study, the inactivation efficacy of in-package high-voltage (80 kV [root mean square]) ACP (HVACP) and the role of intracellular ROS were investigated. Two mechanisms of inactivation were observed in which reactive species were found to either react primarily with the cell envelope or damage intracellular components.Escherichia coliwas inactivated mainly by cell leakage and low-level DNA damage. Conversely,Staphylococcus aureuswas mainly inactivated by intracellular damage, with significantly higher levels of intracellular ROS observed and little envelope damage. However, for both bacteria studied, increasing treatment time had a positive effect on the intracellular ROS levels generated.

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