agar and boric-acid

A new test method for boric acid in agar was developed. After digestion with nitric acid, the concentration of boron was measured by ICP-AES or ICP-MS with internal standards. Collaborative studies involving 5 laboratories were conducted to evaluate the new method by using a finely powdered agar sample and a standard sample (NIST SRM SRM1570a). The repeatability and reproducibility were very good. Moreover, HORRAT(R) values were less than 2. Therefore, it was considered that the new method is acceptable for the determination of boric acid in agar.

Topics: Agar; Boric Acids; Boron; Mass Spectrometry; Spectrophotometry, Atomic

To establish the best method for boric acid susceptibility testing, we compared two agar dilution methods (high and low inoculum) and a standard broth microdilution method (from the National Commitee for Clinical Laboratory Standards document NCCLS M-27A). Saccharomyces cerevisiae (37) and non-C. albicans Candida (39) isolates, as well as one isolate of Trichosporon sp., were included. All were isolated from female workers with vulvovaginitis. Good agreement within a fourfold dilution range was found between the three methods, and only the broth microdilution method versus the agar dilution method with high inoculum showed significant discrepancies. Reading results was easier with the broth microdilution method than with the agar dilution methods because of partial growth inhibition in the latter. In conclusion, broth microdilution is a suitable method for testing yeast susceptibility to boric acid.

Topics: Agar; Anti-Infective Agents, Local; Antifungal Agents; Boric Acids; Candida; Candidiasis, Vulvovaginal; Culture Media; Female; Humans; Microbial Sensitivity Tests; Mycoses; Saccharomyces cerevisiae; Trichosporon; Vulvovaginitis