Economical Agar Dilution Technique for Susceptibility Testing of Anaerobes

Detection with Agar Dilution Susceptibility Testing

A dye reduction method for determining a definitive endpoint with agar dilution susceptibility testing has been developed. Bacterial growth was determined by applying to the inoculum spot a dye solution containing 2-(p-iodophenyl)-3-(pnitrophenyl)-5-phenyltetrazolium chloride and phenazine methosulfate. Viable colonies reduced the tetrazolium salt to a visible red color within 3 to 5 min. The m...

Agar dilution method for susceptibility testing of Neisseria gonorrhoeae.

The antibiotic susceptibilities of Neisseria gonorrhoeae isolates obtained from patients attending a clinic for sexually transmitted diseases in Tucumán, Argentina, were determined by the agar dilution method (MIC). 3.5% of the isolates produced beta-lactamase. A total of 96.5% of beta-lactamase negative isolates tested were susceptible to penicillin (MIC < or = 2 micrograms/ml-1); 14.03% of th...

Agar Gradient Diffusion Susceptibility Testing for Neisseria gonorrhoeae: A Reliable Alternative to Agar Dilution?

Preparing inoculum for susceptibility testing of anaerobes.

We studied six methods for preparation of inoculum to use in susceptibility tests of anaerobic bacteria to determine viable counts of 15 different species of anaerobes. We counted viable bacteria for each method-organism combination. Methods studied included those used for the more routine tests (broth microdilution and broth-disk elution) and for the National Committee for Clinical Laboratory ...

Correlation of netilmicin disk diffusion susceptibility and agar dilution susceptibility.

The minimal inhibitory concentration of netilmicin determined by the agar dilution method was correlated with the disk diffusion zone of inhibition against 322 clinical isolates. Regression line analysis revealed good correlation, r = -0.90, and suggested that isolates with zone sizes </=14 mm should be considered resistant.