Possibility of inferring drug susceptibility using UF-5000, a fully automated analyzer of formed elements in urine

<p>As an approach to resistant bacteria in urinary tract infections, we investigated whether it is possible to estimate the drug susceptibility of such bacteria from changes bacterial count in which a susceptibility disc is directly placed in urine using the UF-5000’s bacterial count measurement function. The drugs used were levofloxacin (LVFX), which is often prescribed for urinary tract infections, and cefotaxime (CTX), which is also used for extended-spectrum β-lactamase (ESBL) judgement. Changes bacterial count after 30, 60, 90, and 120 min were compared. Drug administration/blank value was calculated to determine the cut-off value at which antimicrobial agents can be judged to be effective. For LVFX, if the drug administration/blank value was less than 0.8 within 90 min, the bacteria were assumed to be sensitive, and if it was 0.8 or higher within 90 to 120 min, the bacteria were assumed to be 70 to 80% resistant. For CTX, if the drug administration/blank value was less than 0.8 within 60 min, the bacteria were estimated to be sensitive, and if it was 0.8 or higher, the bacteria were estimated to be 70% resistant. Since CTX alone yielded only 70% accuracy, cefotaxime clavulanate (CTX/C) was added and compared with CTX, focusing on the inhibition of ESBL by clavulanic acid. When the difference in bacterial count between CTX and CTX/C was compared, ESBL could be determined if the difference bacterial count was 800 or larger at each time point, and ESBL could be determined if the difference is a positive integer in CTX and CTX/C at 120 min.</p>