PubMed HealthSearch

PubMed · 8897196

Comparison of inoculation methods for testing enterococci by using vancomycin screening agar.

Abstract

One hundred four recent clinical isolates of Enterococcus species were screened for vancomycin resistance by using inocula of 10(5) or 10(6) CFU dispensed by pipet and by use of a cotton swab dipped in a 0.5 McFarland standard organism suspension applied to the surface of brain heart infusion agar containing 6 micrograms of vancomycin per ml. The three inoculation methods were equivalent in the detection of nonsusceptible isolates. The use of swab inoculation was convenient and less costly than the use of micropipets.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J H Jorgensen, M L McElmeel, C W Trippy. 1996. Comparison of inoculation methods for testing enterococci by using vancomycin screening agar.. https://doi.org/10.1128/jcm.34.11.2841-2842.1996

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Aminoglycoside detection using a universal ELISA binding procedure onto polystyrene microtiter plates in comparison with HPLC analysis and microbiological agar-diffusion assay.

The use of enzyme-linked immunosorbent assay for the detection of aminoglycosides has been hindered due to low molecular weight compound adsorption to solid phases. Here, we describe an enzyme-linked immunosorbent assay based on the treatment of polystyrene microtiter plates with Alcian blue prepared in acetic acid prior to coating with the antibiotic. Whereas no detection of tobramycin was possible on commercially treated or untreated enzyme-linked immunosorbent assay plates, the Alcian blue treatment permitted detection of 0.025 and 0.05 microg ml(-1) of tobramycin respectively using 0.05 and 0.1% of Alcian blue with a coefficient of variation of 1.85 and 7.69%, respectively. Comparative studies of five tobramycin samples of unknown quantity using enzyme-linked immunosorbent assay and high-performance liquid chromatography gave equivalent results while those done via microbiological agar-diffusion assay were an overestimation of the actual quantity. The use of the Alcian blue pretreatment enzyme-linked immunosorbent assay procedure has permitted, in previous studies, the measure of antibodies against synthetic peptides and phospholipids. Subsequently, our demonstration of the sensitivity and reliability of this method in the quantification of tobramycin strongly suggests that the use of Alcian blue pretreatment in enzyme-linked immunosorbent assay can be applied universally to avert molecule immobilization problems on solid phases.

Agar

Magnetic resonance imaging of ultrasonic fields.

A nuclear magnetic resonance imaging (MRI) method is described that allows noninvasive, quantitative mapping of medical ultrasound (US) fields in tissue. Application of a resonant magnetic field gradient operating at the US frequency permits detection of nanometer motions associated with ultrasound, and allows direct measurement of absolute pressure, intensity, and speed of sound. By altering gradient timing, the propagation of US fields in time and space can be observed; this enables tracking of US scattering phenomena in a tissue-equivalent medium. An experimental apparatus was constructed that combined a 515-kHz focused US transducer configured with its focus in the center of a small-bore oscillating gradient. This provided an oscillating gradient with a peak gradient strength of 0.40 T/m over a useable imaging volume of 61 cm3. When used in conjunction with 1.5-T clinical MRI system, this apparatus allowed the clear visualization of the focused US field within this volume and its propagation with time. Current limits of sensitivity indicate a noise equivalent sensitivity of 3.8 nm in displacement amplitude, 19 kPa in pressure amplitude and 12 mW/cm2 in acoustic intensity. These studies indicate that MRI can provide a new, noninvasive method for US exposimetry and the basic study of ultrasound biophysics in tissue.

Agar

Myxococcus xanthus displays Frz-dependent chemokinetic behavior during vegetative swarming.

Myxococcus xanthus has been shown to utilize both directed (tactic) and undirected (kinetic) movements during different stages of its complex life cycle. We have used time-lapse video microscopic analysis to separate tactic and kinetic behaviors associated specifically with vegetatively swarming cells. Isolated individual cells separated by a thin agar barrier from mature swarms showed significant increases in gliding velocity compared to that of similar cells some distance from the swarm. This orthokinetic behavior was independent of the frequency of reversals of gliding direction (klinokinesis) but did require both the Frz signal transduction system and S-motility. We propose that M. xanthus uses Frz-dependent, auto-orthokinetic behavior to facilitate the dispersal of cells under conditions where both cell density and nutrient levels are high.

Agar