Rapid antimicrobial susceptibility testing of urinary tract isolates and samples by flow cytometry.
A multiparametric flow cytometry antimicrobial susceptibility test was developed and its performance was evaluated on clinical urine isolates and samples in comparison with standard methods. Alterations in cytoplasmic membrane integrity were monitored by propidium iodide, and the anionic probe bis-(1,3-dibutylbarbituric acid) trimethine oxonol (DiBAC4(3)) was used to measure changes in membrane potential. Microbial size and cellular content were analysed by light scattering. Twelve antibiotics were tested on 6 ATCC control strains, 22 urine isolates and 19 clinical urine samples, variously containing Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, Enterococcus faecalis, Staphylococcus aureus, S. saprophyticus and S. epidermidis. Agreement between the flow cytometry results, broth microdilution and disk diffusion tests was 93.9% (n = 328 tests). Of the 20 discrepancies observed, 18 were for species other than E. coli. Perfect correlation was obtained with five antibiotics, whereas norfloxacin, nitrofurantoin and tetracycline were responsible for 13(65%) of the 20 discrepancies.
Gauthier
Christian
C
INRS-Institut Armand-Frappier, Laval (Québec), Canada H7V 1B7.
St-Pierre
Yves
Y
Villemur
Richard
R
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D001463:Barbiturates; D013293:Enterococcus faecalis / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects; D005434:Flow Cytometry; D005456:Fluorescent Dyes; D006801:Humans; D007555:Isoxazoles; D007711:Klebsiella pneumoniae / Q000187:drug effects; D008826:Microbial Sensitivity Tests / Q000379:methods*; D011419:Propidium; D011513:Proteus mirabilis / Q000187:drug effects; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D012680:Sensitivity and Specificity; D013210:Staphylococcus / Q000187:drug effects; D014552:Urinary Tract Infections / Q000382:microbiology* / Q000652:urine
D000900:Anti-Bacterial Agents; D001463:Barbiturates; D005456:Fluorescent Dyes; D007555:Isoxazoles; C052795:bis(1,3-dibutylbarbiturate)trimethine oxonol; D011419:Propidium