Diagnosis of bacteriuria and leukocyturia by automated flow cytometry compared with urine culture.
Urinary tract infection (UTI) is a widespread disease, and thus, the most common samples tested in diagnostic microbiology laboratories are urine samples. The "gold standard" for diagnosis is still bacterial culture, but a large proportion of samples are negative. Unnecessary culture can be reduced by an effective screening test. We evaluated the performance of a new urine cytometer, the Sysmex UF-1000i (Dasit), on 703 urine samples submitted to our laboratory for culture. We compared bacteria and leukocyte (WBC) counts performed with the Sysmex UF-1000i to CFU-per-milliliter quantification on CPS agar to assess the best cutoff values. Different cutoff values of bacteria/ml and WBC/ml were compared to give the best discrimination. On the basis of the results obtained in this study, we suggest that when the Sysmex UF-1000i analyzer is used as a screening test for UTI the cutoff values should be 65 bacteria/ml and 100 WBC/ml. Diagnostic performance in terms of sensitivity (98.2%), specificity (62.1%), negative predictive value (98.7%), positive predictive value (53.7%), and diagnostic accuracy (73.3%) were satisfactory. Screening with the Sysmex UF-1000i is acceptable for routine use. In our laboratory, we have reduced the number of bacterial cultures by 43%, speeded up their reporting, and decreased the inappropriate use of antibiotics.
Pieretti
Barbara
B
Laboratorio Analisi Chimiche e Microbiologiche, Ospedale Valduce, Como, Italy. barbara.pieretti@libero.it
Brunati
Pietro
P
Pini
Beatrice
B
Colzani
Carlo
C
Congedo
Pierluigi
P
Rocchi
Marco
M
Terramocci
Riccardo
R
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001419:Bacteria / Q000302:isolation & purification*; D058491:Bacterial Load; D001431:Bacteriological Techniques / Q000379:methods*; D001437:Bacteriuria / Q000175:diagnosis; D002648:Child; D002675:Child, Preschool; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007958:Leukocyte Count; D007962:Leukocytes; D008297:Male; D008875:Middle Aged; D014552:Urinary Tract Infections / Q000175:diagnosis*; D014556:Urine / Q000166:cytology* / Q000382:microbiology*; D055815:Young Adult