Clinical Isolates Of Methicillin Research Articles

The Bioactive Potential of Culturable Fungal Endophytes Isolated From the Leaf of Catharanthus roseus (L.) G. Don.

Endophyte is considered a source of natural bioactive secondary metabolites that provides an array of bioactive lead compounds. The present study was aimed to determine the antimicrobial and anti-inflammatory potential of fungal endophytes isolated from Catharanthus roseus. A total of seven fungal endophytes crude extract were screened against bacterial pathogens. Of these, Curvularia geniculata CATDLF7 crude extract exhibited the most potent inhibitory activity against bacterial pathogens. Hence, CATDLF7 crude extract was subjected to chromatographic separation. This purification leads to the isolation of six pure compounds (1PS - 6PS). Of these, 3PS was found to be a major constituent and most effective against clinical isolates of methicillin- resistant Staphylococcus aureus (MRSA) with minimum inhibitory concentration (MIC) values ranging from 100 to 200 μg/ml. Based on the spectroscopic data, 3PS was characterized as α,β- dehydrocurvularin. This compound also showed synergistic interaction with norfloxacin and reduced its MIC up to 32-folds with a fractional inhibitory concentration index (FICI) of 0.09. To understand the possible antibacterial mechanism of action, α,β-dehydrocurvularin alone (100 μg/ml) exhibited efflux pump inhibitory potential by 0.84 fold decreasing in ethidium bromide (EtBr) fluorescence. In addition, α,β-dehydrocurvularin inhibited inflammatory cytokines TNF-α and IL-6 production, which is further validated by molecular docking scores -4.921 and -5.641, respectively, for understanding orientation and binding affinity. Overall, the results highlighted identifying bioactive compound α,β-dehydrocurvularin, which could be used as an antimicrobial and anti-inflammatory agent.

In Vitro activity of novel glycopolymer against clinical isolates of multidrug-resistant Staphylococcus aureus.

The incidence of multidrug-resistant (MDR) organisms, including methicillin-resistant Staphylococcus aureus (MRSA), is a serious threat to public health. Progress in developing new therapeutics is being outpaced by antibiotic resistance development, and alternative agents that rapidly permeabilize bacteria hold tremendous potential for treating MDR infections. A new class of glycopolymers includes polycationic poly-N (acetyl, arginyl) glucosamine (PAAG) is under development as an alternative to traditional antibiotic strategies to treat MRSA infections. This study demonstrates the antibacterial activity of PAAG against clinical isolates of methicillin and mupirocin-resistant Staphylococcus aureus. Multidrug-resistant S. aureus was rapidly killed by PAAG, which completely eradicated 88% (15/17) of all tested strains (6-log reduction in CFU) in ≤ 12-hours at doses that are non-toxic to mammalian cells. PAAG also sensitized all the clinical MRSA strains (17/17) to oxacillin as demonstrated by the observed reduction in the oxacillin MIC to below the antibiotic resistance breakpoint. The effect of PAAG and standard antibiotics including vancomycin, oxacillin, mupirocin and bacitracin on MRSA permeability was studied by measuring propidium iodide (PI) uptake by bacterial cells. Antimicrobial resistance studies showed that S. aureus developed resistance to PAAG at a rate slower than to mupirocin but similar to bacitracin. PAAG was observed to resensitize drug-resistant S. aureus strains sampled from passage 13 and 20 of the multi-passage resistance study, reducing MICs of mupirocin and bacitracin below their clinical sensitivity breakpoints. This class of bacterial permeabilizing glycopolymers may provide a new tool in the battle against multidrug-resistant bacteria.

Identification and Determination of the Relationship between ccr Alleles and Antibiotic Resistance in Clinical Isolates of Methicillin Resistant Staphylococcus aureus

Identification and Determination of the Relationship between ccr Alleles and Antibiotic Resistance in Clinical Isolates of Methicillin Resistant Staphylococcus aureus

Phenylthiazole antibiotics: A metabolism-guided approach to overcome short duration of action

Antibacterial resistance is a pressing global health challenge that necessitates the development of new therapeutic agents. Phenylthiazole antibacterial agents have been extensively studied, by our group, as a potential novel class of antibiotics to circumvent the scourge of antibacterial resistance. Previously, the phenylthiazole lead compound 1 was shown to possess potent activity against clinical isolates of methicillin- and vancomycin-resistant Staphylococcus aureus (MRSA and VRSA). The promising activity of this novel class of antibiotics is hampered by their short half-life due to rapid hepatic metabolism. In the present study, a metabolic methylene soft spot in the lead 1 was identified and replaced with an oxygen atom. The newly developed phenylthiazoles, with alkoxy side chains, demonstrate high metabolic stability (t1/2 > 4 h), while maintaining their potent anti-MRSA activity. Furthermore, compound 5p demonstrated a selective advantage over vancomycin with its ability to kill intracellular MRSA.

Antistaphylococcal activity of Zataria multiflora essential oil and its synergy with vancomycin

Staphylococcus aureus is recognized as one of the major cause of infections in communities and hospitals. In this study, the chemical composition and antistaphylococcal activity of Zataria multiflora Boiss essential oil were evaluated, along with its synergistic activity with vancomycin. The essential oil was obtained by hydrodistillation from aerial parts of the plant and analyzed using GC and GC-MS. Thymol (38.7%), carvacrol (15.3%) and rho-cymene (10.2%) were the main components of the oil. Antibacterial activity of the oil was evaluated by microbroth dilution assay against clinical isolates of methicillin -resistant (MR) and methicillin-sensitive (MS) strains of S. aureus. The oil showed high antibacterial activity against MRSA and MSSA with minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values in the range of 0.25-1 and 0.5-2microl/ml, respectively. The synergistic action was evaluated by microtiter assay. The essential oil exhibited synergism with vancomycin and displayed the ability to enhance the activity of vancomycin. This study showed that Z. multiflora oil has significant antimicrobial activity against clinical isolates of S. aureus, especially MRSA, and might be useful in controlling MRSA infections.

P2032 Determination of the minimum inhibitory concentration and mutant prevention concentration of tigeycline against clinical isolates of methicillin–susceptible and methicillin–resistant Staphylococcus aureus

P2032 Determination of the minimum inhibitory concentration and mutant prevention concentration of tigeycline against clinical isolates of methicillin–susceptible and methicillin–resistant Staphylococcus aureus

The effect of reserpine, a modulator of multidrug efflux pumps, on the in vitro activity of tetracycline against clinical isolates of methicillin resistant Staphylococcus aureus (MRSA) possessing the tet(K) determinant

The effect of reserpine, a modulator of multidrug efflux pumps, on the in vitro activity of tetracycline against clinical isolates of methicillin resistant Staphylococcus aureus (MRSA) possessing the tet(K) determinant