Effect of ten new beta-lactam antibiotics on urine glucose test methods

The effect of ten new beta-lactam antibiotics (cefoperazone, cefotaxime and its metabolite desacetylcefotaxime, ceftazidime, ceftizoxime, ceftriaxone, aztreonam, azlocillin, mezlocillin, piperacillin, and ticarcillin) on the accuracy of Clinitest, Diastix, and Tes Tape determinations of glycosuria was investigated. Solutions of each of the antibiotics were prepared in urine over a range of clinically obtainable drug concentrations. Urine samples from a healthy subject were used to prepare simulated diabetic urine by adding dextrose to achieve concentrations of 0.5%, 1%, and 2%. With penicillin derivatives, falsely elevated Clinitest readings generally were observed at lower glucose concentrations. When no glucose was present, cephalosporins and the monobactam, aztreonam, gave a dark green-black color that could only be interpreted as 0% on the Clinitest color chart. At higher urine glucose concentrations (1% and 2%), no interaction with Clinitest could be demonstrated, with the exception of a few falsely reduced readings. All urine solutions containing beta-lactam antibiotics were estimated accurately by both Diastix and Tes Tape. The unpredictability of the Clinitest-beta-lactam antibiotics interaction should discourage the use of this urine glucose test in patients who receive these drugs. The glucose-oxidase tests, Diastix and Tes Tape, may be used as qualitative tests for glycosuria in patients treated with beta-lactam antibiotics.