scholarly journals Synergistic Bactericidal Effects of a Sublethal Concentration of Didecyldimethylammonium chloride (DDAC) and Low Concentrations of Nonionic Surfactants against Staphylococcus aureus

2012 ◽  
Vol 17 (4) ◽  
pp. 175-181 ◽  
Author(s):  
MITSUHIRO GOMI ◽  
YUKIHIKO OSAKI ◽  
MIHO MORI ◽  
YOSHIKAZU SAKAGAMI
Keyword(s):  
Staphylococcus Aureus ◽  
Nonionic Surfactants ◽  
Sublethal Concentration ◽  
Low Concentrations ◽  
Bactericidal Effects ◽  
Didecyldimethylammonium Chloride

scholarly journals Manipulation of Autophagy in Phagocytes Facilitates Staphylococcus aureus Bloodstream Infection

2015 ◽  
Vol 83 (9) ◽  
pp. 3445-3457 ◽  
Author(s):  
Kate M. O'Keeffe ◽  
Mieszko M. Wilk ◽  
John M. Leech ◽  
Alison G. Murphy ◽  
Maisem Laabei ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Systemic Infection ◽  
Critical Factor ◽  
Intracellular Survival ◽  
Autophagic Flux ◽  
Content Type ◽  
Bactericidal Effects ◽  
Staphylococcus Aureus Bloodstream Infection ◽  
Direct Killing

The capacity for intracellular survival within phagocytes is likely a critical factor facilitating the dissemination ofStaphylococcus aureusin the host. To date, the majority of work onS. aureus-phagocyte interactions has focused on neutrophils and, to a lesser extent, macrophages, yet we understand little about the role played by dendritic cells (DCs) in the direct killing of this bacterium. Using bone marrow-derived DCs (BMDCs), we demonstrate for the first time that DCs can effectively killS. aureusbut that certain strains ofS. aureushave the capacity to evade DC (and macrophage) killing by manipulation of autophagic pathways. Strains with high levels of Agr activity were capable of causing autophagosome accumulation, were not killed by BMDCs, and subsequently escaped from the phagocyte, exerting significant cytotoxic effects. Conversely, strains that exhibited low levels of Agr activity failed to accumulate autophagosomes and were killed by BMDCs. Inhibition of the autophagic pathway by treatment with 3-methyladenine restored the bactericidal effects of BMDCs. Using anin vivomodel of systemic infection, we demonstrated that the ability ofS. aureusstrains to evade phagocytic cell killing and to survive temporarily within phagocytes correlated with persistence in the periphery and that this effect is critically Agr dependent. Taken together, our data suggest that strains ofS. aureusexhibiting high levels of Agr activity are capable of blocking autophagic flux, leading to the accumulation of autophagosomes. Within these autophagosomes, the bacteria are protected from phagocytic killing, thus providing an intracellular survival niche within professional phagocytes, which ultimately facilitates dissemination.

scholarly journals Bacteriostatic and Bactericidal effects of ethyl acetate root bark extract of Terminalia avicennioides on Methicillin-resistant Staphylococcus aureus

2018 ◽  
Vol 12 (5) ◽  
pp. 45-54
Author(s):  
Ekene Ugochukwu Adim ◽  
Emeka John Dingwoke ◽  
Fatima Amin Adamude ◽  
Chidi Edenta ◽  
Ndubuisi Nwobodo Nwobodo ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Ethyl Acetate ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Bark Extract ◽  
Root Bark ◽  
Methicillin Resistant ◽  
Bactericidal Effects

scholarly journals Antibacterial Peptides Resistance in Staphylococcus aureus: Various Mechanisms and the Association with Pathogenicity

Genes ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1527
Author(s):  
Miki Kawada-Matsuo ◽  
Mi Nguyen-Tra Le ◽  
Hitoshi Komatsuzawa
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Peptides ◽  
Antibacterial Peptides ◽  
Low Concentrations ◽  
Component Systems ◽  
Two Component Systems ◽  
Resistant Strains ◽  
Resistant Mutants ◽  
High Concentrations

Staphylococcus aureus is a bacterium that mainly colonizes the nasal cavity and skin. To colonize the host, it is necessary for S. aureus to resist many antibacterial factors derived from human and commensal bacteria. Among them are the bacteria-derived antimicrobial peptides (AMPs) called bacteriocins. It was reported that some two-component systems (TCSs), which are signal transduction systems specific to bacteria, are involved in the resistance to several bacteriocins in S. aureus. However, the TCS-mediated resistance is limited to relatively low concentrations of bacteriocins, while high concentrations of bacteriocins still exhibit antibacterial activity against S. aureus. To determine whether we could obtain highly bacteriocin-resistant mutants, we tried to isolate highly nisin A-resistant mutants by exposing the cells to sub-minimum inhibitory concentrations (MICs) of nisin A. Nisin A is one of the bacteriocins produced by Lactococcus lactis and is utilized as a food preservative worldwide. Finally, we obtained highly nisin A-resistant mutants with mutations in one TCS, BraRS, and in PmtR, which is involved in the expression of pmtABCD. Notably, some highly resistant strains also showed increased pathogenicity. Based on our findings, this review provides up-to-date information on the role of TCSs in the susceptibility to antibacterial peptides. Additionally, the mechanism for high antimicrobial peptides resistance and its association with pathogenicity in S. aureus is elucidated.

The effect of cotton growth stage on response to a sublethal concentration of 2,4-D

2019 ◽  
Vol 33 (2) ◽  
pp. 321-328 ◽  
Author(s):  
John T. Buol ◽  
Daniel B. Reynolds ◽  
Darrin M. Dodds ◽  
J. Anthony Mills ◽  
Robert L. Nichols ◽  
...  
Keyword(s):  
Fiber Length ◽  
Growth Stage ◽  
Field Experiments ◽  
Fruit Set ◽  
Sublethal Concentration ◽  
Growth Stages ◽  
Visible Injury ◽  
Fiber Properties ◽  
Low Concentrations ◽  
Auxin Herbicides

AbstractRecent commercialization of auxin herbicide–based weed control systems has led to increased off-target exposure of susceptible cotton cultivars to auxin herbicides. Off-target deposition of dilute concentrations of auxin herbicides can occur on cotton at any stage of growth. Field experiments were conducted at two locations in Mississippi from 2014 to 2016 to assess the response of cotton at various growth stages after exposure to a sublethal 2,4-D concentration of 8.3 g ae ha−1. Herbicide applications occurred weekly from 0 to 14 weeks after emergence (WAE). Cotton exposure to 2,4-D at 2 to 9 WAE resulted in up to 64% visible injury, whereas 2,4-D exposure 5 to 6 WAE resulted in machine-harvested yield reductions of 18% to 21%. Cotton maturity was delayed after exposure 2 to 10 WAE, and height was increased from exposure 6 to 9 WAE due to decreased fruit set after exposure. Total hand-harvested yield was reduced from 2,4-D exposure 3, 5 to 8, and 13 WAE. Growth stage at time of exposure influenced the distribution of yield by node and position. Yield on lower and inner fruiting sites generally decreased from exposure, and yield partitioned to vegetative or aborted positions and upper fruiting sites increased. Reductions in gin turnout, micronaire, fiber length, fiber-length uniformity, and fiber elongation were observed after exposure at certain growth stages, but the overall effects on fiber properties were small. These results indicate that cotton is most sensitive to low concentrations of 2,4-D during late vegetative and squaring growth stages.

Growth Effect of Sorbate and Selected Antioxidants on Toxigenic Strains of Staphylococcus aureus1,2

1981 ◽  
Vol 44 (7) ◽  
pp. 531-534 ◽  
Author(s):  
C. LAHELLEC ◽  
D. Y. C. FUNG ◽  
F. E. CUNNINGHAM
Keyword(s):  
Staphylococcus Aureus ◽  
Liquid System ◽  
Growth Effect ◽  
Potassium Sorbate ◽  
Bactericidal Effects ◽  
Test Organisms ◽  
Toxigenic Strains ◽  
Better Than

Effect of potassium sorbate with and without added antioxidants on Staphylococcus aureus 196, S-6, 137 and 326 in a liquid system was evaluated. We found (a) potassium sorbate a 1, 3, and 5% levels in combination with BHA, BHT, PG (50 and 100 ppm) exerted greater bactericidal and bacteriostatic effects on S. aureus strains at pH 5 than at pH 7; at pH 6 the effect was more pronounced at 3 and 5% compared with 1% sorbate, (b) TBHQ was highly inhibitory to S. aureus strains with or without the addition of sorbate, (c) in combination with sorbate, BHA exerted greater bactericidal effects compared with BHT and PG, (d) higher concentration of antioxidants exerted more bactericidal and bacteriostatic effects on test organisms, (e) S. aureus S-6 was more resistant than 196, 326, and 137 in the presence of sorbate and antioxidants and (f) shake cultures of S. aureus grew better than static cultures in the presence of sorbate and BHA.

scholarly journals ISOLATION AND PROPERTIES OF A SURFACE ANTIGEN OF STAPHYLOCOCCUS AUREUS

1962 ◽  
Vol 115 (2) ◽  
pp. 295-311 ◽  
Author(s):  
Stephen I. Morse
Keyword(s):  
Staphylococcus Aureus ◽  
Surface Antigen ◽  
High Titer ◽  
Amino Sugar ◽  
Intradermal Injection ◽  
Aureus Strain ◽  
Isolation And Purification ◽  
Low Concentrations ◽  
Cutaneous Hypersensitivity ◽  
High Concentrations

A technique is described for the isolation and purification of an antigen released into the culture medium by Staphylococcus aureus strain Smith. The antigen was found to be homogeneous when examined by free electrophoresis and analytic ultracentrifugation. Immunologic homogeneity was established by immunoelectrophoresis and quantitative precipitin tests using high titer antiserum prepared against the homologous organism. Chemical analysis showed that the antigen contained 70 per cent carbohydrate, of which approximately 30 to 35 per cent was believed to be glucosamine. The analytic data suggested that another amino sugar, probably carboxylated, was also present, but extreme lability of this compound to mild hydrolytic procedures has thus far precluded further identification. The remainder of the antigen was composed of alanine, glutamic acid, aspartic acid, lysine, glycine, serine, and threonine. No muramic acid was found. The chemical and physical data indicate that the antigen described herein is a previously unrecognized component of Staphylococcus aureus. The purified compound was capable of absorbing agglutinating antibody from antiserum prepared against S. aureus Smith, indicating that it was a surface component of this encapsulated staphylococcus. It is proposed that the antigen be known as the Smith surface antigen (SSA). The injection of SSA into rabbits did not produce precipitating antibodies. However, SSA did precipitate at low concentrations (0.5 µg/ml) with antiserum prepared against S. aureus Smith and one other strain of S. aureus tested. Antiserum against two other aureus strains reacted only with high concentrations of SSA. SSA did not react with S. albus antiserum or with normal sera from several animal species. Experiments are in progress to define further the distribution of SSA. Intradermal injection of small quantities of SSA into rabbits immunized with S. aureus Smith evoked a reaction of cutaneous hypersensitivity, which was maximal in 8 to 12 hours. SSA appeared to be the substance responsible for the ability of S. aureus Smith to resist engulfment by phagocytes, since absorption of Smith antiserum with SSA effectively removed opsonizing antibodies. SSA induced protection in mice against experimental staphylococcal disease. The subcutaneous injection of 0.1 µg resulted in protection against a subsequent intraperitoneal challenge with 50 to 100 LD50's of S. aureus Smith suspended in mucin. Increasing as well as decreasing the immunizing dose resulted in significantly less protection.

scholarly journals The mechanism of folding of globular proteins. Suitability of a penicillinase from Staphylococcus Aureus as a model for refolding studies

1976 ◽  
Vol 155 (2) ◽  
pp. 325-330 ◽  
Author(s):  
B Robson ◽  
R H. Pain
Keyword(s):  
Staphylococcus Aureus ◽  
Enzymic Activity ◽  
Optical Rotatory Dispersion ◽  
Native Conformation ◽  
Guanidinium Chloride ◽  
Tyrosine Residues ◽  
Low Concentrations ◽  
Unfolded State ◽  
Solvent Molecules ◽  
Homogeneous Preparation

1. A homogeneous preparation of penicillinase (penicillin amido-β-lactamhydrolase, EC 3.5.2.6) was isolated and purified from cultures of Staphylococcus aureus by a simple two-stage procedure. 2. The native protein contains 20-30% helix as determined by optical-rotatory-dispersion and circular-dichroism measurements. Some 54(+/-5)% of the 13 tyrosine residues are exposed to solvent molecules of diameter 0.44 and 0.94 nm. 3. Conditions that allow full recovery of enzymic activity and native conformation from the fully unfolded state in 4M-guanidinium chloride were defined. 4. Refolding of the protein was shown to be inhibited by intermolecular interaction, by small changes in ionization and by low concentrations (0.025 M) of phenol.

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