Evaluating antimicrobial efficacy

The ZOI test, also widely known as the Kirby-Bauer disk diffusion test, is a fast in vitro but semiquantitative test [169], The original purpose of this test was to replace the MIC test for small molecule antibiotic efficacy [169], Soon, this method was adopted and modified to evaluate antimicrobial efficacy of silver and polymeric devices with eluting antimicrobial agents [170], Conunonly used eluting antimicrobial agents are zinc salt/particles [171-173], silver salt/particles [173-177], and chlorhexi-dine [178,179], These antimicrobial agents can be compounded/blended into polyurethanes or coated/adsorbed on polyurethanes. 

M.H. Cavanagh, R.E. Burrell, and P.L. Nadworny, Evaluating antimicrobial efficacy of new commercially available silver dressings. Inter. Wound., 7 (5), 394-405,2010. 

The essential oil composition and antimicrobial activity of Osmitopsis asteriscoides (Berg) Less, a medicinal plant used in traditional preparations in South Africa has been investigated [125]. Three different antimicrobial methods were comparatively evaluated against Candida albicans. Staphylococcus aureus and Pseudomonas aeruginosa The two major essential oil components, camphor. Fig. (1) and 1,8-cineole, Fig. (2) were investigated, indieating the positive antimicrobial efficacy of 1,8-cineole, Fig. (2), independently and in combination with camphor, Fig. (1). 

Bernard L, El-Hajj PB, Lotthe A, et al. Outpatient parenteral antimicrobial therapy (OPAT) for the treatment of osteomyelitis Evaluation of efficacy, tolerance and cost. J Clin Pharmacol Ther 2001 26 445 51. 

A Guide for Validation of Neutralizer Systems Used in Topical Antimicrobial Efficacy Evaluations... 

In the smdy reported here, the objective was to evaluate the antimicrobial effectiveness of a 4% CHG used as a full-body shower wash by charting its effect on skin flora of two anatomical sites over the course of a 5-day application period. A test design was developed that would measure the immediate, persistent, and residual effects of the CHG product used in this study. The immediate antimicrobial effects are due to both the mechanical removal of washing and the immediate inactivation by the antimicrobial of microorganisms residing on the skin surface. The persistent antimicrobial effectiveness is a measure of the antimicrobial product s ability to prevent microbial recolonization on the skin surfaces, either by inhibition or by lethality. Finally, the residual antimicrobial efficacy is the measurement of the CHG product s cumulative antimicrobial properties after it has been used repeatedly [7],... 

The optimal study design should be practical, yet provide accurate and reliable results based upon transient microorganism reductions, not resident ones. The healthcare personnel handwash is designed to evaluate the antimicrobial efficacy of products used in the healthcare field and, therefore, is excessively stringent for evaluating consumer product antimicrobial soaps. 

The modified Cade handwash procedure is suboptimal, particularly in that the antimicrobial efficacy is evaluated primarily in terms of reductions in normal microbial flora, which is not appropriate for evaluating consumer antimicrobial hand soaps. Additionally, it measures the residual antimicrobial effectiveness of the test product, not the immediate effects. Finally, a control product is rarely used, so assuring the validity of tlie study is not possible. 

It is important that antimicrobial products be evaluated for efficacy. There are a number of ways to perform these evaluations using quantitative research designs and statistical models. It is also vital that investigators be familiar with a selection of qualitative designs. This will prevent the researcher who has only one tool— a hammer—from viewing everything as a nail. 

Many antimicrobial efficacy evaluations of topical antimicrobial products involve measurements of microbial population reductions at a specific time point after exposure to the product. To determine this accurately, the antimicrobial action of the product must be stopped at the time specified for sample, and it is for this action that neutralizer systems are employed. The validity of the neutralizer system must be established prior to performing the antimicrobial efficacy test. This concern for neutralizer validity has long been known, and a number of methods have been proposed for validating neutralizer systems [1-5]. Each of the methods focuses on two major concerns (1) the neutralizer system must demonstrably neutralize the antimicrobial properties of the product, and (2) the neutralizer system must be proven nontoxic to the test microorganism(s). Few validation methods apply techniques of statistical analysis to the determination of their validity... 

Prior to performing this validation, the researcher should first decide the appropriate dilution ratio of antimicrobial product to the neutralizing fluid. What has been presented is a 1 10 dilution of antimicrobial product to neutralizing fluid. For most antimicrobial efficacy evaluations, especially the time-kill evaluation, this is the highest concentration of product to neutralizer that must be validated. The researcher should take time to calculate the largest amount of antimicrobial product that will be neutralized during the antimicrobial efficacy evaluation and use that amount of product for Phase 4. 

This chapter presented a statistically based method for validating neutralizing systems used in topical antimicrobial efficacy evaluations. This method should be performed prior to performing a topical antimicrobial efficacy evaluation so that the researcher can be assured that the neutralizing system to be used will,... 

SVW Sutton. Neutralizer evaluations as control experiments for antimicrobial efficacy tests. In JM Ascenzi, ed. Handbook of Disinfectants and Antiseptics. New York Marcel Dekker, 1996, pp. 43-62. 

A study published in the March 2002 issue of Biomaterials silicone rubber was studied for the antimicrobial efficacy of the 3-(trimethoxysilyl)-propyldimelhyloctadecylammonium chloride (QAS) on both treated and untreated samples. Gram-positive Stcqyhylococcus aureus, Supl ococcus epidemudis, and Gram-negative Escherichia coli and Pseudomonas aeruginosa were seeded onto both the QAS untreated and treated samples for/n Vitro and In Vivo evaluation. 

Giardino, L., Ambu, E., Savoldi, E., Rimondini, R., CassaneUi, C., Debbia, E.A., 2007. Comparative evaluation of antimicrobial efficacy of sodium hypochlOTite, MTAD, and Tetraclean against Enterococcus faecaUs biofilm. Journal of Endodontics 33, 852—855. Gilani, G.S., Xiao, C., Lee, N., 2008. Need for accurate and standardized determination of amino acids and bioactive peptides for evaluating protein quality and potential health effects of foods and dietary supplements. Journal of AOAC International 91, 894—900. 

The library of silver-NHC compounds has been greatly expanded due to the contributions of Tacke and coworkers (13a-21) [13-17] and Roland et al. (22a-25b) [18]. Compounds 13a-21 (Figure 6.1), all bearing the acetate ligand, were evaluated for their antimicrobial efficacy against S. aureus and . coli using a qualitative Kirby-Bauer disk-diffusion method. The imidazolium salt precursors, silver acetate, and the vehicle (dimethylsulfoxide) served as controls. The results of the tests were mixed, with a number of compounds having a weak... 

Spratt, D. A., Pratten, J., Wilson, M. and Gulabivala, K., 2001. An in vitro evaluation of the antimicrobial efficacy of irrigants on biofilms of root canal isolates. International Endodontic Journal, 34, 300-307. 

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