Evaluation of the Uro-Quick system for antibiotic susceptibility tests of strains collected from intensive care units

Abstract

During the period January-June 2004, 525 pathogens isolated from intensive care units were examined with the new rapid Uro-Quick method for antibiotic susceptibility tests. The results were compared with those obtained by the reference NCCLS methods (disk diffusion or dilution). Antibiotic (in appropriate concentration) was introduced in a vial containing 2 ml of Mueller-Hinton broth, then 0.5 ml of 5 × 105 or 106 cells/ml of the strain culture were added. After 3-6 h of incubation, depending on the microorganism studied, the instrument printed the results: no growth and a growth curve similar to that of the untreated control are representative of a susceptible and resistant strain respectively. The following drugs were tested: ciprofloxacin, ampicillin, aztreonam, co-clavulanate, piperacillin/tazobactam, ceftazidime, cefotaxime, cefuroxime, ceftriaxone, imipenem, amikacin, gentamicin, trimethoprim-sulfamethoxazole, clindamycin, erythromycin, linezolid, penicillin, tetracycline, vancomycin, oxacillin. Gram-negative strains tested were 252 and Gram-positive 273: agreement between the two methods ranged from 85.6% (piperacillin/tazobactam) to 98.5% (ciprofloxacin) in Gram-negative pathogens, from 90 to 100% in Gram-positive, with the exception of erythromycin (84.2%) against enterococci. On the basis of the present findings the Uro-Quick system appears to be very useful for the rapid detection of antibiotic susceptibility in pathogens collected from intensive care units.