Calcineurin inhibitors may augment the effects of antifungal drugs in microbiological assays. We examined this interaction in a microbiological assay for posaconazole. No effect was observed. However, concurrent or recently discontinued treatment with other antifungal drugs caused false-positive results, emphasizing a limitation of microbiological assays for antifungal drug level measurement.

Tobramycin belongs to the aminoglycoside class of antibiotics. Assay procedures were investigated to determine the most suitable methods for the assay of tobramycin in blood, urine, and pharmaceutical preparations. The agar-plate assay was the method of choice for determinations in urine and serum. The turbidimetric assay was selected for the assay of pharmaceutical preparations. An extraction ...

It is generally recognized that the most useful and convenient means of quantitatively determining members of the vitamin B complex involve microbiological methods. Several methods of this type have been proposed for the assay of thiamine but each one in use today possesses certain inherent disadvantages that limit its value. The fermentation method of Schultz, Atkin, and Frey (1,2), based on t...

An agar diffusion assay for chloramphenicol and tetracyclines is described, using inhibition of hemolysis by Clostridium perfringens as a biological indicator of antimicrobial activity. Well-defined zones formed after a 1.5- to 2-h incubation in an anaerobic chamber or after 3 h using a GasPak system. Serum levels of chloramphenicol as low as 2.0 mug/ml could be reproducibly determined with thi...

A multipoint microbiological assay for determining f-lactamase production by clinical isolates of bacteria was evaluated. With strains of Haemophilus influenzae, Neisseria gonorrhoeae, and Branhamella catarrhalis there was excellent correlation between results obtained using this method and those obtained using the chromogenic cephalosporin reference method. The multipoint method is an inexpens...

There has been continued effort in recent years to improve the routine methods of serum folate estimation. The aim has been to make them simpler and more economical to perform while providing more reliable results. Methods have recently become available which claim a number of advantages over conventional bioassays. Here we compare two new methods, a radioisotope method and a fully automated mi...

Enzyme-mediated immunoassay (EMIT) serum aminoglycoside assay results were accurate and precise and correlated well with radioimmunoassay, fluoroimmunoassay, and acetyltransferase and microbiological assay determinations.

A reversed-phase column liquid chromatographic method was developed for the assay of amoxicillin and its preparations. The linear calibration range was 0.2 to 2.0 mg/ml (r = 0.9998), and recoveries were generally greater than 99%. The high-performance liquid chromatographic assay results were compared with those obtained from a microbiological assay of bulk drug substance and capsule, injection...

1. The content of total pantothenic acid (PaA) in two foodstuffs of microbial origin was measured by standard microbiological and chick biological assays. 2. Substantially and consistently higher values were found by the chick assay than by the microbiological determination, indicating that PaA-containing compounds were present that were not utilized by the test micro-organisms but were availab...

leichmannii 313 in tubes and diffusion of oxygen into the medium. Biochem. J., 50, 455-459. LEWIS, J. C., HUMPHREYS, E. M., THOMPSON, P. A., DIMICK, K. P., BENEDICT, R. G., LANGLYKKE, A. F., AND LIGHTBODY, H. 1). 1947 The microbiological assay of subtilin. Arch. Biochem., 14, 437-450. Loy, H. W., JR., HAGGERTY, J. F., AND KLINE, 0. L. 1950 A cause of variation in the microbiological assay for v...