scholarly journals Enhancement of Biofilm Formation by Subinhibitory Concentrations of Macrolides in icaADBC-Positive and -Negative Clinical Isolates of Staphylococcus epidermidis

2010 ◽  
Vol 54 (6) ◽  
pp. 2707-2711 ◽  
Author(s):  
Qian Wang ◽  
Feng-Jun Sun ◽  
Yao Liu ◽  
Li-Rong Xiong ◽  
Lin-Li Xie ◽  
...  
Keyword(s):  
Staphylococcus Epidermidis ◽  
Clinical Relevance ◽  
Biofilm Formation ◽  
Clinical Isolates ◽  
Dependent Manner ◽  
Biofilm Growth ◽  
Subinhibitory Concentrations ◽  
Dose Dependent

ABSTRACT Biofilm formation in Staphylococcus epidermidis is mediated by icaADBC-dependent and -independent pathways. Subinhibitory concentrations of erythromycin, azithromycin, and clarithromycin enhanced, in a dose-dependent manner, the level of biofilm formation by 20% (21/105 isolates) by macrolide-resistant ica-positive and -negative isolates tested in vitro. The presence of ica, however, apparently produced an enhanced effect on biofilm formation. The levels of expression of the biofilm-related genes icaA, atlE, fruA, pyrR, sarA, and sigB were increased in response to erythromycin. The results likely underscore the potential clinical relevance of macrolide-induced biofilm growth.

scholarly journals In vitro activities of cellulase and ceftazidime, alone and in combination against Pseudomonas aeruginosa biofilms

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Esmat Kamali ◽  
Ailar Jamali ◽  
Ahdieh Izanloo ◽  
Abdollah Ardebili
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Biofilm Formation ◽  
Glycoside Hydrolase ◽  
Dependent Manner ◽  
Wound Infections ◽  
Persistent Infections ◽  
Novel Strategy ◽  
Dose Dependent

Abstract Background Biofilms are a main pathogenicity feature of Pseudomonas aeruginosa and has a significant role in antibiotic resistance and persistent infections in humans. We investigated the in vitro activities of antibiotic ceftazidime and enzyme cellulase, either alone or in combination against biofilms of P. aeruginosa. Results Both ceftazidime and cellulase significantly decreased biofilm formation in all strains in a dose-dependent manner. Combination of enzyme at concentrations of 1.25, 2.5, 5, and 10 U/mL tested with 1/16× MIC of antibiotic led to a significant reduction in biofilm biomass. Cellulase showed a significant detachment effect on biofilms at three concentrations of 10 U/mL, 5 U/mL, and 2.5 U/mL. The MIC, MBC, and MBEC values of ceftazidime were 2 to 4 µg/mL, 4 to 8 µg/mL, and 2048 to 8192 µg/mL. When combined with cellulase, the MBECs of antibiotic showed a significant decrease from 32- to 128-fold. Conclusions Combination of the ceftazidime and the cellulase had significant anti-biofilm effects, including inhibition of biofilm formation and biofilm eradication in P. aeruginosa. These data suggest that glycoside hydrolase therapy as a novel strategy has the potential to enhance the efficacy of antibiotics and helps to resolve biofilm-associated wound infections caused by this pathogen.

scholarly journals Activity of Gallidermin on Staphylococcus aureus and Staphylococcus epidermidis Biofilms

2012 ◽  
Vol 56 (11) ◽  
pp. 5804-5810 ◽  
Author(s):  
Jongkon Saising ◽  
Linda Dube ◽  
Anne-Kathrin Ziebandt ◽  
Supayang Piyawan Voravuthikunchai ◽  
Mulugeta Nega ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Immune System ◽  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Physiological State ◽  
Dependent Manner ◽  
Persister Cells ◽  
Content Type ◽  
Killing Activity ◽  
Dose Dependent

ABSTRACTDue to their abilities to form strong biofilms,Staphylococcus aureusandStaphylococcus epidermidisare the most frequently isolated pathogens in persistent and chronic implant-associated infections. As biofilm-embedded bacteria are more resistant to antibiotics and the immune system, they are extremely difficult to treat. Therefore, biofilm-active antibiotics are a major challenge. Here we investigated the effect of the lantibiotic gallidermin on two representative biofilm-forming staphylococcal species. Gallidermin inhibits not only the growth of staphylococci in a dose-dependent manner but also efficiently prevents biofilm formation by both species. The effect on biofilm might be due to repression of biofilm-related targets, such asica(intercellular adhesin) andatl(major autolysin). However, gallidermin's killing activity on 24-h and 5-day-old biofilms was significantly decreased. A subpopulation of 0.1 to 1.0% of cells survived, comprising “persister” cells of an unknown genetic and physiological state. Like many other antibiotics, gallidermin showed only limited activity on cells within mature biofilms.

scholarly journals In vitro activity of allicin against Staphylococcus epidermidis and influence of subinhibitory concentrations on biofilm formation

2003 ◽  
Vol 95 (4) ◽  
pp. 709-711 ◽  
Author(s):  
C. Perez-Giraldo ◽  
G. Cruz-Villalon ◽  
R. Sanchez-Silos ◽  
R. Martinez-Rubio ◽  
M.T. Blanco ◽  
...  
Keyword(s):  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Vitro Activity ◽  
In Vitro Activity ◽  
Subinhibitory Concentrations

scholarly journals Influence of Nisin-Biogel at Subinhibitory Concentrations on Virulence Expression in Staphylococcus aureus Isolates from Diabetic Foot Infections

Antibiotics ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1501
Author(s):  
Carolina Jesus ◽  
Rui Soares ◽  
Eva Cunha ◽  
Miguel Grilo ◽  
Luís Tavares ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Diabetic Foot ◽  
Biofilm Formation ◽  
Guar Gum ◽  
Dependent Manner ◽  
Accessory Gene ◽  
Diabetic Foot Infections ◽  
Subinhibitory Concentrations ◽  
Dose Dependent

A new approach to diabetic foot infections (DFIs) has been investigated, using a nisin-biogel combining the antimicrobial peptide (AMP) nisin with the natural polysaccharide guar-gum. Since in in vivo conditions bacteria may be exposed to decreased antimicrobial concentrations, known as subinhibitory concentrations (sub-MICs), effects of nisin-biogel sub-MIC values corresponding to 1/2, 1/4 and 1/8 of nisin’s minimum inhibitory concentration (MIC) on virulence expression by six Staphylococcus aureus DFI isolates was evaluated by determining bacteria growth rate; expression of genes encoding for staphylococcal protein A (spA), coagulase (coa), clumping factor A (clfA), autolysin (atl), intracellular adhesin A (icaA), intracellular adhesin D (icaD), and the accessory gene regulator I (agrI); biofilm formation; Coa production; and SpA release. Nisin-biogel sub-MICs decreased bacterial growth in a strain- and dose-dependent manner, decreased agrI, atl and clfA expression, and increased spA, coa, icaA and icaD expression. Biofilm formation increased in the presence of nisin-biogel at 1/4 and 1/8 MIC, whereas 1/2 MIC had no effect. Finally, nisin-biogel at sub-MICs did not affect coagulase production, but decreased SpA production in a dose-dependent manner. Results highlight the importance of optimizing nisin-biogel doses before proceeding to in vivo trials, to reduce the risk of virulence factor’s up-regulation due to the presence of inappropriate antimicrobial concentrations.

scholarly journals Formation and properties of in vitro biofilms of ica-negative Staphylococcus epidermidis clinical isolates

2007 ◽  
Vol 56 (1) ◽  
pp. 83-93 ◽  
Author(s):  
Zhiqiang Qin ◽  
Xiaomei Yang ◽  
Lei Yang ◽  
Juan Jiang ◽  
Yuanzhu Ou ◽  
...  
Keyword(s):  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Epidemiological Data ◽  
Clinical Isolates ◽  
Polysaccharide Intercellular Adhesin ◽  
Flow Conditions ◽  
Initial Attachment ◽  
Clinical Strains ◽  
Biofilm Development

Coagulase-negative Staphylococcus epidermidis has become the leading cause of foreign-body infections due to its biofilm formation on all kinds of medical-device surfaces. The biofilm development of S. epidermidis includes two steps: the initial attachment phase and the accumulative phase. In the accumulative phase, the polysaccharide intercellular adhesin (PIA), encoded by the icaADBC locus, is the major component mediating intercellular adhesion. However, recent studies have revealed the emergence of biofilm-positive/ica-negative staphylococcal clinical isolates. In this report, two ica-negative S. epidermidis clinical strains, SE1 and SE4, exhibited their heterogeneity in biofilm architecture under static and flow conditions, compared with the biofilm-positive/ica-positive RP62A strain. Strains with this type of absence of PIA from biofilms also displayed intermediate resistance to vancomycin. More importantly, the cells of both SE1 and SE4 strains were more tolerant than those of RP62A to exposure to lysostaphin and vancomycin. Based on the results, it is suggested that the biofilm-positive/ica-negative strain represents a newly emergent subpopulation of S. epidermidis clinical strains, arising from selection by antibiotics in the nosocomial milieu, which displays a survival advantage in its host environment. Recent epidemiological data support this suggestion, by showing a tendency towards an increasing proportion of this subpopulation in staphylococci-associated infections.

scholarly journals Fluid Flow Induces Biofilm Formation in Staphylococcus epidermidis Polysaccharide Intracellular Adhesin-Positive Clinical Isolates

2012 ◽  
Vol 78 (16) ◽  
pp. 5890-5896 ◽  
Author(s):  
Westbrook M. Weaver ◽  
Vladana Milisavljevic ◽  
Jeff F. Miller ◽  
Dino Di Carlo
Keyword(s):  
Fluid Flow ◽  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Hospital Costs ◽  
Bloodstream Infections ◽  
Clinical Isolates ◽  
Content Type ◽  
Biofilm Structure

ABSTRACTStaphylococcus epidermidisis a common cause of catheter-related bloodstream infections, resulting in significant morbidity and mortality and increased hospital costs. The ability to form biofilms plays a crucial role in pathogenesis; however, not all clinical isolates form biofilms under normalin vitroconditions. Strains containing theicaoperon can display significant phenotypic variation with respect to polysaccharide intracellular adhesin (PIA)-based biofilm formation, including the induction of biofilms upon environmental stress. Using a parallel microfluidic approach to investigate flow as an environmental signal forS. epidermidisbiofilm formation, we demonstrate that fluid shear alone induces PIA-positive biofilms of certain clinical isolates and influences biofilm structure. These findings suggest an important role of the catheter microenvironment, particularly fluid flow, in the establishment ofS. epidermidisinfections by PIA-dependent biofilm formation.

Oxygenation of 18-hydroxycorticosterone as the final reaction for aldosterone biosynthesis

1984 ◽  
Vol 107 (3) ◽  
pp. 395-400 ◽  
Author(s):  
Itaru Kojima ◽  
Etsuro Ogata ◽  
Hiroshi Inano ◽  
Bun-ichi Tamaoki
Keyword(s):  
Carbon Monoxide ◽  
Hydroxysteroid Dehydrogenase ◽  
Dependent Manner ◽  
In Vitro Production ◽  
Mitochondrial Preparation ◽  
Final Reaction ◽  
Vitro Production ◽  
Dose Dependent ◽  
Cytochrome P 450

Abstract. Incubation of 18-hydroxycorticosterone with the sonicated mitochondrial preparation of bovine adrenal glomerulosa tissue leads to the production of aldosterone, as measured by radioimmunoassay. The in vitro production of aldosterone from 18-hydroxycorticosterone requires both molecular oxygen and NADPH, and is inhibited by carbon monoxide. Cytochrome P-450 inhibitors such as metyrapone, SU 8000. SU 10603, SKF 525A, amphenone B and spironolactone decrease the biosynthesis of aldosterone from 18-hydroxycorticosterone. These results support the conclusion that the final reaction in aldosterone synthesis from 18-hydroxycorticosterone is catalyzed by an oxygenase, but not by 18-hydroxysteroid dehydrogenase. By the same preparation, the production of [3H]aldosterone but not [3H]18-hydroxycorticosterone from [1,2-3H ]corticosterone is decreased in a dose-dependent manner by addition of non-radioactive 18-hydroxycorticosterone.

Appraisal of Immunological Impacts of Melaleuca leucadendra Extract over Macrophage Performance in Vitro

2020 ◽  
Keyword(s):  
Nitric Oxide ◽  
Interleukin 2 ◽  
Dependent Manner ◽  
Reduced Pressure ◽  
Medical Plant ◽  
Dose Dependent ◽  
Level Production ◽  
Melaleuca Leucadendra ◽  
Phagocytic Killing

This trial research was performed to discuss the immune-influence of Melaleuca leucadendra ‘paper-bark tree’ dried leaves which is an important medical plant known in many regions in the world. The leaves were dissolved in a mixture of (ethanol + water) (3:1) mixture, then filtered, evaporated and dried under reduced pressure to obtain leaves extract. The macrophages of blood derived origin were provided from rats and mixed with three different leaves extracts doses in tissue culture plates and incubated then stained with fluorescent acridine orange and examined under fluorescent microscope to assess the phagocytic and killing potency. The wells contents were aspirated and assayed for nitric oxide and interleukin-2 levels. The results displayed an obvious increase in phagocytic, killing performance as well as nitric oxide and IL-2 level production than control in a dose dependent manner. The obtained results suggested the immune-stimulant impact of the paper-bark tree leaves.

Serotonin elicits long-lasting enhancement of rhythmic respiratory activity in turtle brain stems in vitro

2001 ◽  
Vol 91 (6) ◽  
pp. 2703-2712 ◽  
Author(s):  
Stephen M. Johnson ◽  
Julia E. R. Wilkerson ◽  
Daniel R. Henderson ◽  
Michael R. Wenninger ◽  
Gordon S. Mitchell
Keyword(s):  
Brain Stem ◽  
Respiratory Activity ◽  
Dependent Manner ◽  
Frequency Increase ◽  
Burst Frequency ◽  
Bath Application ◽  
Burst Amplitude ◽  
Dose Dependent ◽  
The Brain

Brain stem preparations from adult turtles were used to determine how bath-applied serotonin (5-HT) alters respiration-related hypoglossal activity in a mature vertebrate. 5-HT (5–20 μM) reversibly decreased integrated burst amplitude by ∼45% ( P < 0.05); burst frequency decreased in a dose-dependent manner with 20 μM abolishing bursts in 9 of 13 preparations ( P < 0.05). These 5-HT-dependent effects were mimicked by application of a 5-HT1A agonist, but not a 5-HT1B agonist, and were abolished by the broad-spectrum 5-HT antagonist, methiothepin. During 5-HT (20 μM) washout, frequency rebounded to levels above the original baseline for 40 min ( P < 0.05) and remained above baseline for 2 h. A 5-HT3 antagonist (tropesitron) blocked the post-5-HT rebound and persistent frequency increase. A 5-HT3 agonist (phenylbiguanide) increased frequency during and after bath application ( P < 0.05). When phenylbiguanide was applied to the brain stem of brain stem/spinal cord preparations, there was a persistent frequency increase ( P < 0.05), but neither spinal-expiratory nor -inspiratory burst amplitude were altered. The 5-HT3receptor-dependent persistent frequency increase represents a unique model of plasticity in vertebrate rhythm generation.

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