Kill Curve Determination

ABSTRACT Vertilmicin is a new semisynthetic aminoglycoside with a structure similar to that of netilmicin except for a methyl group at the C-6′ position. In the present study, the in vitro antibacterial activity of vertilmicin was studied, and its susceptibility to modifications by the recombinant aminoglycoside bifunctional modifying enzyme AAC(6′)-APH(2″) was compared with those of verdamicin and netilmicin. A total of 1,185 clinical isolates collected from hospitals in Beijing between 2000 and 2001 were subjected to the in vitro antibacterial activity evaluations, including MIC, minimum bactericidal concentration (MBC), and time-kill curve tests. The MICs were evaluated in non-gentamicin-resistant (gentamicin-susceptible and gentamicin-intermediate) strains and gentamicin-resistant strains, respectively. For most of the non-gentamicin-resistant bacteria (except for the isolates of Pseudomonas spp.), the MIC90s of vertilmicin were in the range of 0.5 to 8 μg/ml, comparable to those of the reference aminoglycosides. For the gentamicin-resistant isolates, the three semisynthetic aminoglycosides (vertilmicin, netilmicin, and amikacin) demonstrated low MIC50s and/or MIC90s, as well as high percent susceptibility values. Among the study drugs, vertilmicin showed the lowest MIC90s, 16 μg/ml, for the gram-positive gentamicin-resistant isolates of Staphylococcus aureus and Staphylococcus epidermidis. Meanwhile, vertilmicin was a potent bactericidal agent, with MBC/MIC ratios in the range of 1 to 2 for Escherichia coli, Klebsiella pneumoniae, and S. aureus and 1 to 4 for S. epidermidis. The time-kill curve determination further demonstrated that this effect was rapid and concentration dependent. In evaluations of susceptibility to modifications by the recombinant AAC(6′)-APH(2″) with maximum rate of metabolism/Km measurements, vertilmicin exhibited susceptibilities to both acetylation and phosphorylation lower than those of netilmicin and verdamicin.

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Damage Curve Determination of Dual-Phase Steel Based on Micromechanical Damage by Using Numerical Analysis and Experimental Investigation

International Institute of Engineers (IIE) June 18-19, 2015 Pattaya (Thailand) ◽

10.15242/iie.e0615037 ◽

2015 ◽

Keyword(s):

Experimental Investigation ◽

Numerical Analysis ◽

Dual Phase Steel ◽

Dual Phase ◽

Micromechanical Damage ◽

Curve Determination

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pH Dependent Release Potential of Natural Polymers in Sustained Release of Ornidazole From Colon Targeted Delivery System)

International Journal of Drug Delivery Technology ◽

10.25258/ijddt.9.2.4 ◽

2019 ◽

Vol 9 (02) ◽

Author(s):

Sharma Pankaj ◽

Tailang Mukul

Keyword(s):

Drug Release ◽

Delivery System ◽

Targeted Delivery ◽

Guar Gum ◽

Acidic Environment ◽

Natural Polymers ◽

Weight Variation ◽

Curve Determination ◽

Preformulation Studies

The aim of present work was to prepare colon specific delivery system of Ornidazole using different ratio of shellac, zein and guar gum. From study of various literature it revealed that shellac, zein and guar gum released drug from dosage form at the pH of 6.9, 11.5, 7-9 respectively. The main problem associated with colon targeted drug delivery system is degradation of drug in the acidic environment of stomach to circumvent the present problem different combinations of shellac, zein and guar gum were employed in the formulation of colon targeted tablet. Several preformulation parameters were determined such as melting point, FTIR spectroscopy, preparation of calibration curve, determination of λmax and partition coefficient. After the preformulation studies, next steps were preparation of core tablets, evaluation of core of tablets and coating of tablets. The data obtained from preformulation study seven formulations were developed and evaluated for various parameters. Based on evaluated parameter such as weight variation, friability, dissolution study, invitro drug release etc. the F7 formulation show better results colon targeted tablets. Drug content in F7 formulation was 95% and drug release after 6 hrs was 96%. Formulation containing combination of shellac, zein and guar gum released least amount of drug in the acidic environment of stomach and released most of the drug in colon. It is evide

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Trans-Cinnamaldehyde Exhibits Synergy with Conventional Antibiotic against Methicillin-Resistant Staphylococcus aureus

International Journal of Molecular Sciences ◽

10.3390/ijms22052752 ◽

2021 ◽

Vol 22 (5) ◽

pp. 2752

Author(s):

Shu Wang ◽

Ok-Hwa Kang ◽

Dong-Yeul Kwon

Keyword(s):

Staphylococcus Aureus ◽

Methicillin Resistant Staphylococcus Aureus ◽

Synergistic Effects ◽

Regulatory Gene ◽

Western Blot Assay ◽

Methicillin Resistant ◽

Wide Range ◽

Kill Curve ◽

Conventional Antibiotics ◽

Time Kill

Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen worldwide and has acquired multiple resistance to a wide range of antibiotics. Hence, there is a pressing need to explore novel strategies to overcome the increase in antimicrobial resistance. The present study aims to investigate the efficacy and mechanism of plant-derived antimicrobials, trans-cinnamaldehyde (TCA) in decreasing MRSA’s resistance to eight conventional antibiotics. A checkerboard dilution test and time–kill curve assay are used to determine the synergistic effects of TCA combined with the antibiotics. The results indicated that TCA increased the antibacterial activity of the antibiotics by 2-16-fold. To study the mechanism of the synergism, we analyzed the mecA transcription gene and the penicillin-binding protein 2a level of MRSA treated with TCA by quantitative RT-PCR or Western blot assay. The gene transcription and the protein level were significantly inhibited. Additionally, it was verified that TCA can significantly inhibit the biofilm, which is highly resistant to antibiotics. The expression of the biofilm regulatory gene hld of MRSA after TCA treatment was also significantly downregulated. These findings suggest that TCA maybe is an exceptionally potent modulator of antibiotics.

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Thermodynamic and Kinetic Calculation of Non-Equilibrium Microstructure Design of TRIP Steel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.783-786.766 ◽

2014 ◽

Vol 783-786 ◽

pp. 766-770

Author(s):

Yan Lin He ◽

Na Qiong Zhu ◽

Wei Sen Zheng ◽

Xiao Gang Lu ◽

Lin Li

Keyword(s):

Trip Steel ◽

Equilibrium Phase ◽

Microstructure Design ◽

Kinetic Calculation ◽

Software Comparison ◽

Thermo Calc Software ◽

Curve Determination ◽

Equilibrium Microstructure ◽

The Relationship ◽

Non Equilibrium

The non-equilibrium microstructure of Fe-C-Mn-Si TRIP steel is designed bythermodynamic and kinetic calculation. The upper limit of bainitic transformation temperature iscalculated and compared to that characterized by CCT curve determination. s M temperature isdetermined based on thermodynamics of martensitic transformation and sublattice model. Thecalculation is conducted via TQ6-patch in Thermo-Calc software. Comparison between thecalculations and experiments reveals the relationship between non-equilibrium phase compositionand heat treatment parameters which can be utilized to achieve the elaborate design of alloy and heattreatment for super TRIP steel.

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Low temperature J-resistance curve determination of asphalt concrete using wavelet-Radon transform

Journal of Central South University ◽

10.1007/s11771-013-1769-3 ◽

2013 ◽

Vol 20 (9) ◽

pp. 2563-2569

Author(s):

Ghafari Sepehr ◽

Moghadas Nejad Fereidoon ◽

Aflaki Esmail

Keyword(s):

Low Temperature ◽

Radon Transform ◽

Asphalt Concrete ◽

Resistance Curve ◽

Curve Determination

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Characterization of bactericidal activity of clindamycin against Bacteroides fragilis via kill curve methods.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.40.8.1941 ◽

1996 ◽

Vol 40 (8) ◽

pp. 1941-1944 ◽

Cited By ~ 11

Author(s):

M E Klepser ◽

M A Banevicius ◽

R Quintiliani ◽

C H Nightingale

Keyword(s):

Bactericidal Activity ◽

Bacteroides Fragilis ◽

Kill Curve

Kill curves were determined for five isolates of Bacteroides fragilis with clindamycin at concentrations equal to the MIC or to 4, 16, and 64 times the MIC. Examination of plots of log CFU per milliliter versus time revealed no association between the clindamycin concentration and the rate and extent of the bactericidal activity against B. fragilis at or below 64 times the MIC.

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