Inactivation of gentamicin (G) is known to occur secondarily to the formation of complexes with certain beta-lactam antibiotics. However, aminoglycosides in the presence of aminoglycoside-beta-lactam complexes may not be recognized uniformly by all assay methods. We tested this hypothesis by using mixtures of G plus carbenicillin (C), with and without the addition of penicillinase, in pooled se...

It was reported previously that coenzyme A contained pantothenic acid bound in such a manner as to make it unavailable in microbiological tests (1). A liberation of p;alanine on acid hydrolysis indicated early the presence of pantothenic acid, which was confirmed by chick assay (2). While the chick assay for pantothenic acid and the p-alanine assay by the yeast growth test yielded equivalent am...

A microbiological assay was developed for bleomycin, an antitumor antibiotic reported to be active in human trials. The assay bacterium was a strain of Escherichia coli which is resistant to ethionine. Studies revealed relatively high concentrations of bleomycin in the blood and urine of mice after a single dose, < 0.33 ld(10), injected intraperitoneally.