History and development of antimicrobial susceptibility testing methodology

Wheat, P. F.

doi:10.1093/jac/48.suppl_1.1

Cited by 81 publications

(55 citation statements)

References 34 publications

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“…Antimicrobial susceptibility tests can be difficult to standardize [38], but they are widely used to determine important quantitative pharmacodynamic parameters characterizing the inhibitory relationship between antibiotic and bacteria [39]. For bacteriostatic antibiotics, a dose-response curve that showing densities at a given timepoint at a series of increasing dosages characterizes the effect of the drug.…”

Section: Population Heterogeneities and Non-monotonic Dose -Responsementioning

confidence: 99%

Testing the optimality properties of a dual antibiotic treatment in a two-locus, two-allele model

Peña‐Miller

Fuentes-Hernández

Reding

et al. 2014

J. R. Soc. Interface.

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Mathematically speaking, it is self-evident that the optimal control of complex, dynamical systems with many interacting components cannot be achieved with 'non-responsive' control strategies that are constant through time. Although there are notable exceptions, this is usually how we design treatments with antimicrobial drugs when we give the same dose and the same antibiotic combination each day. Here, we use a frequency-and densitydependent pharmacogenetics mathematical model based on a standard, two-locus, two-allele representation of how bacteria resist antibiotics to probe the question of whether optimal antibiotic treatments might, in fact, be constant through time. The model describes the ecological and evolutionary dynamics of different sub-populations of the bacterium Escherichia coli that compete for a single limiting resource in a two-drug environment. We use in vitro evolutionary experiments to calibrate and test the model and show that antibiotic environments can support dynamically changing and heterogeneous population structures. We then demonstrate, theoretically and empirically, that the best treatment strategies should adapt through time and constant strategies are not optimal.

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Section: Population Heterogeneities and Non-monotonic Dose -Responsementioning

confidence: 99%

Testing the optimality properties of a dual antibiotic treatment in a two-locus, two-allele model

Peña‐Miller

Fuentes-Hernández

Reding

et al. 2014

J. R. Soc. Interface.

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“…For that reason, the Clinical and Laboratory Standard Institute (CLSI) and similar organizations have established reference standards for antibiotic susceptibility testing (AST) methods and for determining pharmacokinetic (PK)/pharmacodynamics (PD) breakpoints and clinical values. Using a standard testing method, we can determine the minimum inhibitory concentration (MIC) and inhibition zone diameter, which indicate whether the pathogen is sensitive or resistant to antibiotics used in clinical practice [1][2][3]. Over the years numerous countries around the world have been committed to the standardization of AST and surveillance of antibiotic-resistant bacteria [4][5][6][7].…”

mentioning

confidence: 99%

Accurate assessment of antibiotic susceptibility and screening resistant strains of a bacterial population by linear gradient plate

Liu

et al. 2011

Sci. China Life Sci.

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The dynamics of a bacterial population exposed to the minimum inhibitory concentration (MIC) of an antibiotic is an important issue in pharmacological research. Therefore, a novel antibiotic susceptibility test is urgently needed that can both precisely determine the MIC and accurately select antibiotic-resistant strains from clinical bacterial populations. For this purpose, we developed a method based on Fick's laws of diffusion using agar plates containing a linear gradient of antibiotic. The gradient plate contained two layers. The bottom layer consisted of 15 mL agar containing the appropriate concentration of enrofloxacin and allowed to harden in the form of a wedge with the plate slanted such that the entire bottom was just covered. The upper layer consisted of 15 mL plain nutrient agar added with the plate held in the horizontal position. After allowing vertical diffusion of the drug from the bottom agar layer for 12 h, the enrofloxacin concentration was diluted in proportion to the ratio of the agar layer thicknesses. The uniform linear concentration gradient was verified by measuring the enrofloxacin concentration on the agar surface. When heavy bacterial suspensions were spread on the agar surface and incubated for more than 12 h, only resistant cells were able to form colonies beyond the boundary of confluent growth of susceptible cells. In this way, the true MIC of enrofloxacin was determined. The MICs obtained using this linear gradient plate were consistent with those obtained using conventional antibiotic susceptibility tests. Discrete colonies were then spread onto a gradient plate with higher antibiotic concentrations; the boundary line increased significantly, and gene mutations conferring resistance were identified. This new method enables the rapid identification of resistant strains in the bacterial population. Use of the linear gradient plate can easily identify the precise MIC and reveal the dynamic differentiation of bacteria near the MIC. This method allows the study of genetic and physiological characteristics of individual strains, and may be useful for early warning of antibiotic resistance that may occur after use of certain antimicrobial agents, and guide clinical treatment.

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“…The metabolites are known to diffuse in three dimensions so agar with shallow depths will have the metabolite diffusing more and thus producing large halo zones in contrast to agar with deeper depths. These factors in combination result in each combination having a unique ability in formation of the zone of inhibition indicating susceptibility of the test bacteria to the antimicrobial substance (Jorgensen andFerraro, 2009 andWheat, 2001). Point at which critical mass is reached for the compounds is indicated by a sharp margin of the halo zone beyond which no inhibitory activity was evidenced.…”

Section: Discussionmentioning

confidence: 99%

Isolation, characterization and primary screening of soil actinomycetes from Kenyatta University arboretum grounds for antibacterial activities

Khasabuli¹,

Kibera²

2014

J. App. Bioscience.

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Objective : Antimicrobial resistance has increased drastically in recent years in the developing countries, and it has leading public health concern. With almost all organisms becoming multidrug resistant to the commonly used antibiotics, there is a need to search for more drugs that are novel in order to address this challenge. Therefore, this study was aimed at isolating antimicrobial producing actinomyscetes and to evaluate their secondary metabolites against selected multidrug resistant bacteria isolates. Methodology: Half kg soil samples were collected 15cm below the ground. Starch Casein Agar (SCA) was used to isolate actinomycetes. Fifteen different actinomycetes identified as Is.1-Is.15 were isolated. They were differentiated based on the difference in appearance of the colony morphology and mycelial structure. Their metabolites were tested for antibiotic activities through the primary screening using the disk diffusion methods. Test bacteria were; Bacillus subtilis, E.coli, Klebsiella Pneumoniae, Staphylococcus aureus, Shigella sonei and Salmonella typhi. All the secondary metabolites from the isolated actinomycetes proved to posses the ability to inhibit bacterial growth by formation of different sized halo zones. Conclusion and application: Secondary metabolites produced by actinomycetes have the ability to inhibit growth of pathogenic bacteria. The ability of these metabolites to inhibit growth of test pathogenic bacteria has been attributed to the establishment of the fact that novel antibiotics can be manufactured from metabolites produced by actinomycetes. Large scale manufacture can be done through purification of these metabolites to ensure large scale production of novel drugs. This can serve help clear pathogenic bacteria that are ever developing resistance on the available antibiotics.

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History and development of antimicrobial susceptibility testing methodology

Cited by 81 publications

References 34 publications

Testing the optimality properties of a dual antibiotic treatment in a two-locus, two-allele model

Testing the optimality properties of a dual antibiotic treatment in a two-locus, two-allele model

Accurate assessment of antibiotic susceptibility and screening resistant strains of a bacterial population by linear gradient plate

Isolation, characterization and primary screening of soil actinomycetes from Kenyatta University arboretum grounds for antibacterial activities

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