scholarly journals In vitro susceptibility of Staphylococcus aureus to thrombin-induced platelet microbicidal protein-1 (tPMP-1) is influenced by cell membrane phospholipid composition and asymmetry

Microbiology ◽  
2007 ◽  
Vol 153 (4) ◽  
pp. 1187-1197 ◽  
Author(s):  
Kasturi Mukhopadhyay ◽  
William Whitmire ◽  
Yan Q Xiong ◽  
Jaime Molden ◽  
Tiffanny Jones ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Membrane ◽  
Phospholipid Composition ◽  
Membrane Phospholipid ◽  
In Vitro Susceptibility ◽  
Platelet Microbicidal Protein

scholarly journals Transposon Disruption of the Complex I NADH Oxidoreductase Gene (snoD) in Staphylococcus aureus Is Associated with Reduced Susceptibility to the Microbicidal Activity of Thrombin-Induced Platelet Microbicidal Protein 1

2006 ◽  
Vol 188 (1) ◽  
pp. 211-222 ◽  
Author(s):  
Arnold S. Bayer ◽  
Peter McNamara ◽  
Michael R. Yeaman ◽  
Natalie Lucindo ◽  
Tiffanny Jones ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Complex I ◽  
Enzyme Inhibitor ◽  
Nadh:Ubiquinone Oxidoreductase ◽  
Gene Products ◽  
Chromosomal Dna ◽  
In Vitro Susceptibility ◽  
Ph Tolerance ◽  
Platelet Microbicidal Protein

ABSTRACT The cationic molecule thrombin-induced platelet microbicidal protein 1 (tPMP-1) exerts potent activity against Staphylococcus aureus. We previously reported that a Tn551 S. aureus transposon mutant, ISP479R, and two bacteriophage back-transductants, TxA and TxB, exhibit reduced in vitro susceptibility to tPMP-1 (tPMP-1r) compared to the parental strain, ISP479C (V. Dhawan, M. R. Yeaman, A. L. Cheung, E. Kim, P. M. Sullam, and A. S. Bayer, Infect. Immun. 65:3293-3299, 1997). In the current study, the genetic basis for tPMP-1r in these mutants was identified. GenBank homology searches using sequence corresponding to chromosomal DNA flanking Tn551 mutant strains showed that the fourth gene in the staphylococcal mnh operon (mnhABCDEFG) was insertionally inactivated. This operon was previously reported to encode a Na+/H+ antiporter involved in pH tolerance and halotolerance. However, the capacity of ISP479R to grow at pH extremes and in high NaCl concentrations (1 to 3 M), coupled with its loss of transmembrane potential (ΔΨ) during postexponential growth, suggested that the mnh gene products are not functioning as a secondary (i.e., passive) Na+/H+ antiporter. Moreover, we identified protein homologies between mnhD and the nuo genes of Escherichia coli that encode components of a complex I NADH:ubiquinone oxidoreductase. Consistent with these data, exposures of tPMP-1-susceptible (tPMP-1s) parental strains (both clinical and laboratory derived) with either CCCP (a proton ionophore which collapses the proton motive force) or pieracidin A (a specific complex I enzyme inhibitor) significantly reduced tPMP-induced killing to levels seen in the tPMP-1r mutants. To reflect the energization of the gene products encoded by the mnh operon, we have renamed the locus sno (S. aureus nuo orthologue). These novel findings indicate that disruption of a complex I enzyme locus can confer reduced in vitro susceptibility to tPMP-1 in S. aureus.

scholarly journals DltABCD- and MprF-Mediated Cell Envelope Modifications of Staphylococcus aureus Confer Resistance to Platelet Microbicidal Proteins and Contribute to Virulence in a Rabbit Endocarditis Model

2005 ◽  
Vol 73 (12) ◽  
pp. 8033-8038 ◽  
Author(s):  
Christopher Weidenmaier ◽  
Andreas Peschel ◽  
Volkhard A. J. Kempf ◽  
Natalie Lucindo ◽  
Michael R. Yeaman ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Parental Strain ◽  
Cell Envelope ◽  
Teichoic Acid ◽  
Infection Model ◽  
In Vitro Susceptibility ◽  
Surface Envelope ◽  
Platelet Microbicidal Protein

ABSTRACT The DltABCD and MprF proteins contribute a net positive charge to the Staphylococcus aureus surface envelope by alanylating and lysinylating teichoic acids and membrane phosphatidylglycerol, respectively. These surface charge modifications are associated with increased in vitro resistance profiles of S. aureus to a number of endogenous cationic antimicrobial peptides (CAPs), such as α-defensins. The current study investigated the effects of dltA and mprF mutations on the following host factors relevant to endovascular infections: (i) in vitro susceptibility to the CAP thrombin-induced platelet microbicidal protein 1 (tPMP-1), (ii) in vitro adherence to endothelial cells (EC) and matrix proteins, and (iii) in vivo virulence in an endovascular infection model (rabbit endocarditis) in which tPMP-1 is felt to play a role in limiting S. aureus pathogenesis. Both mutations resulted in substantial increases in the in vitro susceptibility to tPMP-1 compared to that of the parental strain. The dltA (but not the mprF) mutation resulted in a significantly reduced capacity to bind to EC in vitro, while neither mutation adversely impacted in vitro binding to fibronectin, fibrinogen, or platelets. In vivo, both mutations significantly attenuated virulence in terms of early colonization of sterile vegetations and subsequent proliferation at this site (versus the parental strain). However, only the dltA mutation significantly reduced metastatic infections in kidneys and spleens compared to those in animals infected with the parental strain. These data underscore the importance of resistance to distinct CAPs and of teichoic acid-dependent EC interactions in the context of endovascular infection pathogenesis.

scholarly journals In Vitro Resistance of Staphylococcus aureus to Thrombin-Induced Platelet Microbicidal Protein Is Associated with Alterations in Cytoplasmic Membrane Fluidity

2000 ◽  
Vol 68 (6) ◽  
pp. 3548-3553 ◽  
Author(s):  
Arnold S. Bayer ◽  
Rajendra Prasad ◽  
Jyotsna Chandra ◽  
Anjni Koul ◽  
M. Smriti ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Membrane ◽  
Membrane Fluidity ◽  
Cytoplasmic Membrane ◽  
Membrane Lipids ◽  
Serial Passage ◽  
Membrane Structure And Function ◽  
Platelet Microbicidal Protein ◽  
And Function

ABSTRACT Platelet microbicidal proteins (PMPs) are small, cationic peptides which possess potent microbicidal activities against common bloodstream pathogens, such as Staphylococcus aureus. We previously showed that S. aureus strains exhibiting resistance to thrombin-induced PMP (tPMP-1) in vitro have an enhanced capacity to cause human and experimental endocarditis (T. Wu, M. R. Yeaman, and A. S. Bayer, Antimicrob. Agents Chemother. 38:729–732, 1994; A. S. Bayer et al., Antimicrob. Agents Chemother. 42:3169–3172, 1998; V. K. Dhawan et al., Infect. Immun. 65:3293–3299, 1997). However, the mechanisms mediating tPMP-1 resistance in S. aureus are not fully delineated. The S. aureus cell membrane appears to be a principal target for the action of tPMP-1. To gain insight into the basis of tPMP-1 resistance, we compared several parameters of membrane structure and function in three tPMP-1-resistant (tPMP-1r) strains and their genetically related, tPMP-1-susceptible (tPMP-1s) counterpart strains. The tPMP-1rstrains were derived by three distinct methods: transposon mutagenesis, serial passage in the presence of tPMP-1 in vitro, or carriage of a naturally occurring multiresistance plasmid (pSK1). All tPMP-1r strains were found to possess elevated levels of longer-chain, unsaturated membrane lipids, in comparison to their tPMP-1s counterparts. This was reflected in corresponding differences in cell membrane fluidity in the strain pairs, with tPMP-1r strains exhibiting significantly higher degrees of fluidity as assessed by fluorescence polarization. These data provide further support for the concept that specific alterations in the cytoplasmic membrane of S. aureus strains are associated with tPMP-1 resistance in vitro.

scholarly journals Thrombin-Induced Platelet Microbicidal Protein Susceptibility Phenotype Influences the Outcome of Oxacillin Prophylaxis and Therapy of Experimental Staphylococcus aureus Endocarditis

2000 ◽  
Vol 44 (11) ◽  
pp. 3206-3209 ◽  
Author(s):  
V. K. Dhawan ◽  
A. S. Bayer ◽  
M. R. Yeaman
Keyword(s):  
Staphylococcus Aureus ◽  
Infective Endocarditis ◽  
In Vitro Susceptibility ◽  
Platelet Microbicidal Protein ◽  
Model Treatment ◽  
Staphylococcus Aureus Endocarditis ◽  
Susceptibility Profiles ◽  
Vancomycin Treatment ◽  
Resistant Cells

ABSTRACT We previously showed that in vitro susceptibility profiles ofStaphylococcus aureus to thrombin-induced platelet microbicidal protein 1 (tPMP-1) impacted the outcome of vancomycin treatment in experimental infective endocarditis. In this same model, treatment with oxacillin (a more rapid staphylocidal agent than vancomycin) enhanced the clearance of both tPMP-1-susceptible and -resistant cells from vegetations. The extent of clearance was greater for tPMP-1-susceptible cells.

Systematic analysis and integrative discovery of active-site subpocket-specific dehydroquinate synthase inhibitors combating antibiotic-resistant Staphylococcus aureus infection

2018 ◽  
Vol 16 (06) ◽  
pp. 1850027
Author(s):  
Quanfeng Liu ◽  
Liping Li ◽  
Fei Xu
Keyword(s):  
Staphylococcus Aureus ◽  
Active Site ◽  
Shikimate Pathway ◽  
In Vitro Susceptibility ◽  
Systematic Analysis ◽  
Antibiotic Resistant ◽  
Enzyme Active Site ◽  
Specific Inhibitors ◽  
Dehydroquinate Synthase

Shikimate pathway plays an essential role in the biosynthesis of aromatic amino acids in various plants and bacteria, which consists of seven key enzymes and they are all attractive targets for antibacterial agent development due to their absence in humans. The Staphylococcus aureus dehydroquinate synthase (SaDHQS) is involved in the second step of shikimate pathway, which catalyzes the NAD[Formula: see text]-dependent conversion of 3-deoxy-D-arabino-heptulosonate-7-phosphate to dehydroquinate via multiple steps. The enzyme active site can be characterized by two spatially separated subpockets 1 and 2, which represent the reaction center of substrate adduct with NAD[Formula: see text] nicotinamide moiety and the assistant binding site of NAD[Formula: see text] adenine moiety, respectively. In silico virtual screening is performed against a biogenic compound library to discover SaDHQS subpocket-specific inhibitors, which were then tested against both antibiotic-sensitive and antibiotic-resistant S. aureus strains by using in vitro susceptibility test. The activity profile of hit compounds has no considerable difference between the antibiotic-sensitive and -resistant strains. The subpocket 1-specific inhibitors exhibit a generally higher activity than subpocket 2-specific inhibitors, and they also hold a strong selectivity between their cognate and noncognate subpockets. Dynamics and energetics analyses reveal that the SaDHQS active site prefers to interact with amphipathic and polar inhibitors by forming multiple hydrogen bonds and van der Waals packing at the complex interfaces of the two subpockets with their cognate inhibitors.

Increase in the in vitro susceptibility of Staphylococcus aureus to antimicrobial agents in the presence of Candida albicans

1979 ◽  
Vol 25 (4) ◽  
pp. 429-435 ◽  
Author(s):  
J. deRepentigny ◽  
R. Lévesque ◽  
L. G. Mathieu
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Candida Albicans ◽  
Inhibitory Activity ◽  
Antimicrobial Agents ◽  
Mixed Cultures ◽  
Alpha Toxin ◽  
In Vitro Susceptibility ◽  
Pure Cultures

In experiments with mixed cultures of Staphylococcus aureus and Candida albicans both in the absence and in the presence of 5-fluorocytosine (5-FC), we have observed that (1) there is an inhibition of S. aureus growth in mixed cultures with C. albicans in media supplemented with 1 μg/mL of 5-FC and that 5-FC has no effect on staphylococci in pure cultures; (2) this inhibition occurred with clinically isolated and laboratory strains and could be reversed by specific metabolites; (3) Staphylococcus aureus was inhibited by filtrates of C. albicans cultures treated with 5-FC and this seemed to be favored by some C. albicans filterable product which can affect the cell wall and the permeability of the staphylococcal cells since they become sensitive to 5-FC; (4) nine other commonly used antimicrobials showed an increased inhibitory activity against S. aureus in mixed cultures with C. albicans; and (5) there is a decrease in the number of precipitating antigens of S. aureus and of the activity of alpha toxin when this species was grown with both C. albicans and 5-FC. Our results indicate that the susceptibility of some species to antimicrobials could be significantly modified in the presence of other species. One cannot exclude that a similar phenomenon could happen in hosts under treatment with antibiotics against infection.

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