Evaluation of the Uro-Quick, a New Rapid Automated System, for the Detection of Well-Characterized Antibiotic-Resistant Bacteria

Abstract

The Uro-Quick system has been employed to detect antibiotic resistance ingenotypically and/or phenotypically well-characterized bacterial species includingthose that might not be easily identified by routine procedure. In order to achievefull agreement between the antibiotic susceptibility results obtained by the reference method (NCCLS) and the Uro-Quick system, the optimal experimental conditions (inoculum size, time of incubation and antibiotic concentration) for each strain to be used by the automatic system were determined. The shorter time periods for generation of correct susceptibility results were 180 min for ampicillin- and ciprofloxacin-resistant Escherichia coli and for ESBL- and Inhibitor-resistant TEM (IRT)-producing E. coli; 360 min for penicillin-susceptible Streptococcus pneumoniae, as well as for strains with reduced susceptibility to this antibiotic (both intermediate, and resistant isolates). The same time was required to detect erythromycin-resistant pneumococci irrespective of their mechanism of resistance (ribosomal methylation and efflux-mediated), Streptococcus pyogenes exhibiting the three erythromycin-resistance phenotypes (constitutive, inducible and M-type) and Klebsiella pneumoniae, Enterobacter aerogenes, Enterobacter cloacae, Serratia marcescens, Proteus mirabilis and Moraxella morganii refractory to third-generation cephalosporins, aminoglycosides, ciprofloxacin and other classes of antimicrobial agents; 480 min for penicillin-resistant, constitutive and inducible oxacillinresistant (OXA-R) Staphylococcus aureus and OXA-R Staphylococcus epidermidis. The same period of time was also necessary to find the great majority of drug-resistance exhibited by Pseudomonas aeruginosa. Teicoplanin-resistant Staphylococcus haemolyticus, vancomycin-resistant (VanA, VanB, VanC) highlevel aminoglycoside-resistant (HLAR) Enterococcus spp, and imipenem-resistant P. aeruginosa required longer incubation (24 h) to be detected. The results obtained indicate that Uro-Quick might be a reliable and promising instrument for the correct detection of the above antibiotic resistance markers.

Keywords:

• Uro-Quick
• detection of antibiotic resistance
• well-characterized
• antibiotic resistance
• susceptibility testing