title: Does flow cytometry have a role in preliminary differentiation between urinary tract infections sustained by gram positive and gram negative bacteria? An Italian polycentric study.
abstract: BACKGROUND
  Urine culture is the most frequently requested test for a Microbiology Lab. A reliable screening tool would be of paramount importance both to clinicians and laboratorians, provided that it could get fast and accurate negative results in order to rule-out urinary tract infection (UTI).
  
  
  METHODS
  We evaluated 1907 consecutive urine samples from outpatients. Culture was performed on chromogenic agar with 1μL loop, using 10(5)CFU/mL as a limit of positive growth. Using Sysmex Uf-1000i analyzer we evaluated bacteria forward scatter (B_FSC) and fluorescent light scatter (B_FLH) in a preliminary discrimination step for UTI caused by Gram+ or Gram- bacteria.
  
  
  RESULTS
  We got 512 positive samples. A mono-microbial infection was observed in 490 samples; two bacterial strains were isolated in 22 samples, so 534 bacterial strains were found: 392 Gram-, 133 Gram+ and 9 yeasts. Comparing Gram+ and Gram- bacteria we observed a statistically significant difference for B_FSC but not for B_FLH. In this application experimental cut-off value for B_FSC was 25ch. Using this cut-off to perform a presumptive identification of UTI sustained by Gram-+ bacteria, we observed a SE 0.68, SP 0.84.
  
  
  CONCLUSIONS
  Our data although preliminary suggest that B_FSC could be useful in presumptive exclusion of UTI caused by Gram-positive bacteria.
authors.affiliation: Clinical Pathology Dept., Madonna della Navicella Hospital, Chioggia, VE, Italy. Electronic address: ggessoni@asl14chioggia.veneto.it.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Gessoni
authors.affiliation: Clinical Chemistry and Microbiology Laboratory, Orlandi Hospital, Bussolengo, VR, Italy.
authors.forename: Graziella
authors.initials: G
authors.lastname: Saccani
authors.affiliation: Clinical Pathology Dept., Madonna della Navicella Hospital, Chioggia, VE, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Valverde
authors.affiliation: Clinical Pathology Dept., Civil Hospital, Monselice, PD, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Manoni
authors.affiliation: Clinical Chemistry and Microbiology Laboratory, Fracastoro Hospital, S. Bonifacio, VR, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Caputo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001431:Bacteriological Techniques; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D006090:Gram-Negative Bacteria / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology*; D006094:Gram-Positive Bacteria / Q000302:isolation & purification; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014552:Urinary Tract Infections / Q000382:microbiology*; D014556:Urine / Q000382:microbiology; D055815:Young Adult
keywords: B_FSC; Bacteriuria; Gram discrimination; UF-1000i; UTI