scholarly journals Vescalagin and Castalagin Present Bactericidal Activity toward Methicillin-Resistant Bacteria

2021 ◽  
Author(s):  
Ana R. Araújo ◽  
Ana C. Araújo ◽  
Rui L. Reis ◽  
Ricardo A. Pires
Keyword(s):  
Bactericidal Activity ◽  
Resistant Bacteria ◽  
Methicillin Resistant

scholarly journals Activity of Ceftaroline against Aerobic Gram-Positive and Gram-Negative Pathogens: Effect of Test Method Variability

2011 ◽  
Vol 2011 ◽  
pp. 1-5
Author(s):  
Diane M. Citron ◽  
Yumi A. Warren ◽  
Kerin L. Tyrrell ◽  
Ellie J. C. Goldstein
Keyword(s):  
Bactericidal Activity ◽  
Test Method ◽  
In Vitro Test ◽  
Gram Negative ◽  
Methicillin Resistant ◽  
E Coli ◽  
Minimum Inhibitory Concentrations ◽  
Test Conditions ◽  
Vitro Test

Ceftaroline is a new cephalosporin with bactericidal activity against methicillin-resistant S. aureus (MRSA) as well as gram-negative pathogens. Variations of in vitro test conditions were found to affect ceftaroline activity, with 5% NaCl inhibiting growth and/or reducing the minimum inhibitory concentrations (MICs) for E. coli, K. pneumoniae, M. catarrhalis, H. influenzae, and streptococci, while an inoculum of 106 CFU/mL raised MICs of some E. coli, K. pneumoniae, and M. catarrhalis strains.

scholarly journals Telavancin, a Multifunctional Lipoglycopeptide, Disrupts both Cell Wall Synthesis and Cell Membrane Integrity in Methicillin-Resistant Staphylococcus aureus

2005 ◽  
Vol 49 (3) ◽  
pp. 1127-1134 ◽  
Author(s):  
Deborah L. Higgins ◽  
Ray Chang ◽  
Dmitri V. Debabov ◽  
Joey Leung ◽  
Terry Wu ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Bactericidal Activity ◽  
Bacterial Cell ◽  
Cell Membrane Potential ◽  
Gram Positive ◽  
Methicillin Resistant ◽  
Bacterial Cell Membrane

ABSTRACTThe emergence and spread of multidrug-resistant gram-positive bacteria represent a serious clinical problem. Telavancin is a novel lipoglycopeptide antibiotic that possesses rapid in vitro bactericidal activity against a broad spectrum of clinically relevant gram-positive pathogens. Here we demonstrate that telavancin's antibacterial activity derives from at least two mechanisms. As observed with vancomycin, telavancin inhibited late-stage peptidoglycan biosynthesis in a substrate-dependent fashion and bound the cell wall, as it did the lipid II surrogate tripeptideN,N′-diacetyl-l-lysinyl-d-alanyl-d-alanine, with high affinity. Telavancin also perturbed bacterial cell membrane potential and permeability. In methicillin-resistantStaphylococcus aureus, telavancin caused rapid, concentration-dependent depolarization of the plasma membrane, increases in permeability, and leakage of cellular ATP and K+. The timing of these changes correlated with rapid , concentration-dependent loss of bacterial viability, suggesting that the early bactericidal activity of telavancin results from dissipation of cell membrane potential and an increase in membrane permeability. Binding and cell fractionation studies provided direct evidence for an interaction of telavancin with the bacterial cell membrane; stronger binding interactions were observed with the bacterial cell wall and cell membrane relative to vancomycin. We suggest that this multifunctional mechanism of action confers advantageous antibacterial properties.

Nemonoxacin enhances antibacterial activity and anti-resistant mutation ability of vancomycin against methicillin-resistant Staphylococcus aureus in an in vitro dynamic pharmacokinetic/pharmacodynamic model

2021 ◽  
Author(s):  
Junchen Huang ◽  
Siwei Guo ◽  
Xin Li ◽  
Fang Yuan ◽  
You Li ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antibacterial Activity ◽  
Bactericidal Activity ◽  
Pharmacodynamic Model ◽  
Methicillin Resistant ◽  
Mutant Prevention Concentration ◽  
Mrsa Infection ◽  
Independent Risk Factors ◽  
Resistant Mutation

Reduced susceptibility and emergence of resistance to vancomycin in methicillin-resistant Staphylococcus aureus (MRSA) have led to the development of various vancomycin based combinations. Nemonoxacin is a novel nonfluorinated quinolone with antibacterial activity against MRSA. The present study aimed to investigate the effects of nemonoxacin on antibacterial activity and the anti-resistant mutation ability of vancomycin for MRSA and explore whether quinolone resistance genes are associated with a reduction in the vancomycin minimal inhibitory concentration (MIC) and mutant prevention concentration (MPC) when combined with nemonoxacin. Four isolates, all with a vancomycin MIC of 2 μg/mL, were used in a modified in vitro dynamic pharmacokinetic/pharmacodynamic model to investigate the effects of nemonoxacin on antibacterial activity (M04, M23 and M24) and anti-resistant mutation ability (M04, M23 and M25, all with MPC ≥19.2 μg/mL) of vancomycin. The mutation sites of gyrA , gyrB , parC , and parE of 55 clinical MRSA isolates were sequenced. We observed that in M04 and M23, the combination of vancomycin (1g q12h) and nemonoxacin (0.5g qd) showed a synergistic bactericidal activity and resistance enrichment suppression. All clinical isolates resistant to nemonoxacin harbored gyrA (S84→L) mutation; gyrA (S84→L) and parC (E84→K) mutations were the two independent risk factors for the unchanged vancomycin MPC in combination. Nemonoxacin enhances the bactericidal activity and suppresses resistance enrichment ability of vancomycin against MRSA with a MIC of 2 μg/mL. Our in vitro data support the combination of nemonoxacin and vancomycin for the treatment of MRSA infection with a high MIC.

scholarly journals Vancomycin In Vitro Bactericidal Activity and Its Relationship to Efficacy in Clearance of Methicillin-Resistant Staphylococcus aureus Bacteremia

2007 ◽  
Vol 51 (7) ◽  
pp. 2582-2586 ◽  
Author(s):  
Pamela A. Moise ◽  
George Sakoulas ◽  
Alan Forrest ◽  
Jerome J. Schentag
Keyword(s):  
Staphylococcus Aureus ◽  
Median Time ◽  
Bactericidal Activity ◽  
Peak Plasma ◽  
Plasma Concentrations ◽  
Accessory Gene ◽  
Vancomycin Therapy ◽  
Methicillin Resistant ◽  
Vancomycin Mics

ABSTRACT We examined the relationship between the time to clearance of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia while patients were receiving vancomycin therapy and the in vitro bactericidal activity of vancomycin. Vancomycin killing assays were performed with 34 MRSA bloodstream isolates (17 accessory gene regulator group II [agr-II] and 17 non-agr-II isolates) from 34 different patients with MRSA bacteremia for whom clinical and microbiological outcomes data were available. Vancomycin doses were prospectively adjusted to achieve peak plasma concentrations of 28 to 32 μg/ml and trough concentrations of 8 to 12 μg/ml. Bactericidal assays were performed over 24 h with ∼107 to 108 CFU/ml in broth containing 16 μg/ml vancomycin. The median time to clearance of bacteremia was 6.5 days for patients with MRSA isolates demonstrating ≥2.5 reductions in log10 CFU/ml at 24 h and >10.5 days for patients with MRSA isolates demonstrating <2.5 log10 CFU/ml by 24 h (P = 0.025). The median time to clearance was significantly longer with MRSA isolates with vancomycin MICs of 2.0 μg/ml compared to that with MRSA isolates with MICs of ≤1.0 μg/ml (P = 0.019). The bacteremia caused by MRSA isolates with absent or severely reduced delta-hemolysin expression was of a longer duration of bacteremia (10 days and 6.5 days, respectively; P = 0.27) and had a decreased probability of eradication (44% and 78%, respectively; P = 0.086). We conclude that strain-specific microbiological features of MRSA, such as increased vancomycin MICs and decreased killing by vancomycin, appear to be predictive of prolonged MRSA bacteremia while patients are receiving vancomycin therapy. Prolonged bacteremia and decreased delta-hemolysin expression may also be related. Evaluation of these properties may be useful in the consideration of antimicrobial therapies that can be used as alternatives to vancomycin for the treatment of MRSA bacteremia.

Tolerability of a probiotic in subjects with a history of methicillin-resistant Staphylococcus aureus colonisation

2014 ◽  
Vol 5 (4) ◽  
pp. 389-395 ◽  
Author(s):  
S. Warrack ◽  
P. Panjikar ◽  
M. Duster ◽  
N. Safdar
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Medical Center ◽  
Controlled Trial ◽  
Academic Medical Center ◽  
Resistant Bacteria ◽  
Public Health Importance ◽  
Methicillin Resistant ◽  
History Of ◽  
Study Population

Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogen of major public health importance. Colonisation precedes infection; thus reducing MRSA carriage may be of benefit for reducing infection. Probiotics represent a novel approach to reducing MRSA carriage. We undertook a pilot feasibility randomised controlled trial of the tolerability and acceptability of probiotics for reducing nasal and intestinal carriage of MRSA. In addition, subjects were screened for vancomycin-resistant enterocococci (VRE). Subjects with a history of MRSA were recruited from a large, academic medical center and randomised to take either a placebo or probiotic (Lactobacillus rhamnosus HN001). Subjects returned to the clinic after four weeks for further testing to determine adherence to the probiotic regimen and colonisation of MRSA. 48 subjects were enrolled and randomised. Nearly 25% were transplant recipients and 30% had diabetes. The probiotic was well tolerated in the study population though minor side effects, such as nausea and bloating, were observed. A majority of the subjects randomised to HN001 had good adherence to the regimen. At the four week time point among subjects randomised to the probiotic, MRSA was detected in 67 and 50% of subjects colonised in the nares and the gastrointestinal tract, respectively. Three subjects who initially tested positive for VRE were negative after four weeks of probiotic exposure. Probiotics were well tolerated in our study population of largely immunocompromised subjects with multiple comorbidities. Adherence to the intervention was good. Probiotics should be studied further for their potential to reduce colonisation by multidrug resistant bacteria.

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